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  1. #1
    Philip Lamachio's Avatar
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    Exclamation Catostrophic Plaster Ceiling Collapse

    Fellow Inspectors,

    Previously I had a post on the hidden dangers of certain plaster ceiling systems installed between 1920 and 1960.

    I have been researching a particular collapse case and have received some solid information along with photographs sent to me by Tom Donatelli, who was the Alleghany Public Works Director in PA. at the time (2005) that this dramatic plaster ceiling collapse occured.

    Tom wrote to me via email and said:

    I believe that it is important to note that there were absolutely no signs of any water damage or deterioration of the ceiling joists what so ever.

    The ceiling failure was catastrophic in that there was no signs that the ceiling was about to collapse.

    I can recall that we had a series of 90 degree days in a row and it was extremely dry.

    Upon inspection of the failed ceiling we noted that the nails that fastened the metal lath only penetrated into the ceiling joists about ¼ inch and they were not serrated but smooth.

    Though Tom notes the warm days preceeding the collapse, I don't see this as an important contributing factor. Certainly there had been other hot days since this ceiling had been installed. Based on other things he has said above,it looks like this was a disaster just waiting to happen.

    Oh, Mr. Donatelli also said that a group of tourists had just left the room. In his own estimation, he believes that people could have been killed had they been in the room at the time.

    Thanks,
    Philip LaMachio
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    Default Re: Catastrophic Plaster Ceiling Collapse

    Phillip,

    It also happens on new construction projects.

    Not with plaster but with the ceilings falling in.

    About 2 years ago, as I recall, a new construction project had the metal framed ceiling attached with shot pins and bent tabs from non-structural metal framing used to secured it all came crashing down on workers still working in the area, a large recreation room or dining room as I recall.

    I had been calling that out for several years after seeing a large ceiling in a living room and dining room sag. It was non-structural 25 gage metal framing attached to a concrete deck above it. The ends of the metal framing studs were cut to leave a tab which was bent 90 degrees and shot pinned to the concrete deck. Other places just had cut pieces from 25 gage studs and used as 'L' brackets, shot pinned to the concrete deck and framing screwed to the metal studs.

    The means of attachment was only discovered after I pointed the sagging ceiling out to my client, the builder protested too much, delaying doing anything for about 2 weeks, during which time it sagged even further and cracks in the drywall formed. When they ripped the drywall off they found the thin sheet metal tabs and 'L' brackets had straightened out, the shot pins did not have washers and many had pulled the 25 gage sheet metal over the heads of the pins, and the ceiling was not very many days, or maybe even hours, from falling as your photos show.

    That was about 5-6 years ago, then the new construction ceiling fell (I had been telling everyone who would listen that a structural engineer needed to design those attachments, some listened, others did not, and when they listened, the structural engineer did not accept that method of anchoring, he had them use stronger brackets and stronger fasteners).

    Just letting you, and everyone, know that it IS NOT just old ceilings which can, AND DO, fall ... that new construction ceilings are also prone to it, especially where metal framing is used to fur down a ceiling from above ... ALWAYS ... ALWAYS ... ALWAYS be suspicious of those supports and their fasteners.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Catostrophic Plaster Ceiling Collapse

    The ceiling failure was catastrophic in that there was no signs that the ceiling was about to collapse.
    I find it very difficult to believe that there were no signs that the ceiling was about to collapse. This lath and plaster is pre 1940 and I've yet to see one that old that doesn't show cracks, sagging, or previously patched areas.

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  4. #4
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    Default Re: Catostrophic Plaster Ceiling Collapse

    Quote Originally Posted by Ken Rowe View Post
    I find it very difficult to believe that there were no signs that the ceiling was about to collapse. This lath and plaster is pre 1940 and I've yet to see one that old that doesn't show cracks, sagging, or previously patched areas.
    This was the statement from Tom Donatelli, which I quoted directly from an email I received from him yesterday.

    Some factors to consider:

    • This ceiling was much higher than a normal ceiling (Don't know the exact height at the moment), but the point is, any sagging or cracking may have gone unnoticed by the curators of the building.
    • The only full metal mesh ceiling I have ever seen did not show any signs of sagging. However, it was also securly attached.
    I think you do bring up a very important point.

    It is my opinion that ALL transitional plaster ceiling systems should be inspected for signs of failure, which is why I am posting this information on this forum. (At what intervals I can't say)


  5. #5
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    Default Re: Catostrophic Plaster Ceiling Collapse

    'That was about 5-6 years ago, then the new construction ceiling fell (I had been telling everyone who would listen that a structural engineer needed to design those attachments, some listened, others did not, and when they listened, the structural engineer did not accept that method of anchoring, he had them use stronger brackets and stronger fasteners).'

    I empathise with your attempt to address that issue. When you have seen something with your own eyes more than once, you begin to put two and two together. But conveying your conclusions to others and convincing them is the hard part.

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    Default Re: Catostrophic Plaster Ceiling Collapse

    Philip
    If I remember correctly,in your fist thread you warned about collapse of "transitional plaster ceilings. Gyp rock with holes in it for the plaster to hold to.
    But this is wire lath.
    Seems the problem is more about how the lath is fastened. Is that right?

    Thanks for pointing this out to us.

    Note to self.
    Add to list of disclaimers, pg 37 paragraph 4.
    Does not include...


    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

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    Default Re: Catostrophic Plaster Ceiling Collapse

    Quote Originally Posted by Rick Cantrell View Post
    Philip
    If I remember correctly,in your fist thread you warned about collapse of "transitional plaster ceilings. Gyp rock with holes in it for the plaster to hold to.
    But this is wire lath.
    Seems the problem is more about how the lath is fastened. Is that right?

    Thanks for pointing this out to us.

    Note to self.
    Add to list of disclaimers, pg 37 paragraph 4.
    Does not include...
    I agree this was not rock lath it was expanded metal lath and not properly installed. This was not the first ceiling for this room, although those can be older than the begining of the OPs "transitional" period of 1920.

    from Preservation Brief 21: Repairing Historic Flat Plaster--Walls and Ceilings:

    Metal lath, patented in England in 1797, began to be used in parts of the United States toward the end of the 19th century. The steel making up the metal lath contained many more spaces than wood lath had contained. These spaces increased the number of keys; metal lath was better able to hold plaster than wood lath had been.
    Rock Lath. A third lath system commonly used was rock lath (also called plaster board or gypsum-board lath). In use as early as 1900, rock lath was made up of compressed gypsum covered by a paper facing. Some rock lath was textured or perforated to provide a key for wet plaster. A special paper with gypsum crystals in it provides the key for rock lath used today; when wet plaster is applied to the surface, a crystalline bond is achieved.

    Rock lath was the most economical of the three lathing systems. Lathers or carpenters could prepare a room more quickly. By the late 1930s, rock lath was used almost exclusively in residential plastering
    Rock lath 16 x 36"
    Rock lath is 16x36-inch, 1/2-inch thick, gypsum-core panel covered with absorbent paper with gypsum crystals in the paper. The crystals in the paper bond the wet plaster and anchor it securely. This type of lath requires two coats of new plaster -- the brown coat and the finish coat. The gypsum lath itself takes the place of the first, or scratch, coat of plaster.
    A Modern Replacement System
    Veneer Plaster. Using one of the traditional lath and plaster systems provides the highest quality plaster job. However, in some cases, budget and time considerations may lead the owner to consider a less expensive replacement alternative. Designed to reduce the cost of materials, a more recent lath and plaster system is less expensive than a two-or-three coat plaster job, but only slightly more expensive than drywall. This plaster system is called veneer plaster.

    The system uses gypsum-core panels that are the same size as drywall (4x8 feet), and specially made for veneer plaster. They can be installed over furring channels to masonry walls or over old wood lath walls and ceilings. Known most commonly as "blue board," the panels are covered with a special paper compatible with veneer plaster. Joints between the 4-foot wide sheets are taped with fiberglass mesh, which is bedded in the veneer plaster. After the tape is bedded, a thin, 1/16-inch coat of high-strength veneer plaster is applied to the entire wall surface. A second veneer layer can be used as the "finish" coat, or the veneer plaster can be covered with a gauged lime finish-coat--the same coat that covers ordinary plaster.
    The collapsed ceiling in question was not original to the building, but a failed prior remediation/replacement appears to have used a portland based scratch and attached directly to joists futher than 16" OC not upon strapping installed 90 and more frequently spaced. This was an accident waiting to happen. Fibers may indicate a stablizing fiber mesh may have been applied and new finish to hide/correct previously occuring cracks. See dangling tape in the photo as well.

    The affects of rhythemic structural vibration caused by hoards of folks walking (such as in guided tours) on a under engineered structure are well documented. Collapses of people bridges, department store floors, etc. surprised it lasted as long as it did, especially with the various phases of work done (repair, modernization, and restoration efforts) over the years.

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    Default Re: Catostrophic Plaster Ceiling Collapse

    "This was not the first ceiling for this room,..."

    What makes you think that?

    ' correct a wise man and you gain a friend... correct a fool and he'll bloody your nose'.

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    Default Re: Catostrophic Plaster Ceiling Collapse

    Lets just say inside information.

    I was prepared for this as PL made a point of broadcasting this would be a defense and more evidence supporting his prior posts on rock lath by sending me a PM several days ago.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    IRC 2009 Chapter 7 – 702.3.6 (all new) and 702.3.7 - .702.3.8 and 702.3.8.1
    In performing progress inspections I always checked the length of nail or screw attachment and almost 25% of the time they where to short ! But of course when you understand that a good half of the construction crews can’t read a tape-measure it makes perfect sense.

    Jerry McCarthy
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  11. #11
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    Default Re: Catostrophic Plaster Ceiling Collapse

    In response to my chief detractor, HG Watson:

    As far as the question as to whether this was the original ceiling or not, or whether there had been repairs or otherwise prior to the collapse, I will ask Tom Donatelli about that. I think he is in a much better position to determine that than you or I. (He never mentioned any of this to me in our e-mails...I'm curious as to your 'sources'. )

    Those questions aside, the central point is still intact.

    The whole point of this and other posts is inadequate attachment systems.

    Also, if you had read my page on 'transitional ceilings' carefully, you would have seen that I noted that there were several types of such ceilings, including wire mesh.

    Again, the crucial point of failure is the attachment point, which in this case was smooth nails.

    The affects of rhythemic structural vibration caused by hoards of folks walking (such as in guided tours) on a under engineered structure are well documented. Collapses of people bridges, department store floors, etc. surprised it lasted as long as it did, especially with the various phases of work done (repair, modernization, and restoration efforts) over the years.
    HG...how do you determine whether this ceiling collapse is due to human foot traffic rather than inadequate attachment?

    I do not deny contributary causes, esp. vibration. However, do you think this collapse would have been as likely to occur, even with contributary causes, if the installers had used ring shank or spiral maze nails and had insured they had penetrated the joists more than 1/4" deep?

    In the effort one-up me, let's not ignore the elephant in the room.

    Other than that, you have some informative quotes in you post.


    Lets just say inside information.
    Maybe you installed the ceiling that failed?

    Last edited by Philip Lamachio; 11-15-2009 at 07:11 AM.

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    Default Re: Catostrophic Plaster Ceiling Collapse

    1. Ms. Sylvia Easler, (recreation superintendent, county parks department) whose experience/records during her tenure since the mid 80s had been aware of problems during her employment. Numerous occasions of chandelliers SHAKING, SWINGING, Moving. Cracks "repaired". Ms. Easler's response to concerned staff and others, to dismiss it as: ITS THE GHOSTS. The "haunting" of the mansion supposedly by the ghosts of Mr. John W (died in the 50s) and Mrs. Lawrence (Mary Flinn Lawrence) have been blamed for numerous issues which when reveiwed (exception those that claim to have seen figures walking around) are indications of PROBLEMS with the Building (i.e. swinging, shaking chandelliers when no windows open, no wind; piano and organ making noises, no ghosts weren't playing it - vibrations; doors which refuse to stay open, automatically close - again not a wind/pressure issue; furniture on casters moving on floor; mysterious staining on walls & celings; creaking, cracking, howling,, groaning noises often noted, and blamed on "the ghosts", etc.). This "haunting" attribution has been covered in books and media.

    2. The mansion was in need of repairs at the time it was sold retaining a life tennancy in 1969. It was tendered upon Mrs. Lawrence's death in late 1974. The County had actually tried to condem the 480-acre (at the time described as a 482-acre tract) estate as a part of an overall plan that included numerous additional (15 smaller) tracts which totaled 856 acres. There were defenses to some of these "taking" actions. The County's "plans" were publically announced and accounts were published in 67 and 68 (objections filed in Common Pleas Court in Oct. 67; Mr. Kelly's admissions to press inquiries and committee and board meetings with other governmental bodies in Spring 1968). Mrs. Lawrence negotiated a "deal" which was "below market value" in 1969, which included all personal effects and contents, allowed her possession until her death, prevented development until that time, and contained restrictions and covenants for the use (and keeping the mansion as a tribute to her family). The land and its landscaping alone was valued at well over 1 million at that time. It is no surprise that any significant investment of maintenance, especially expensive maintenance, repair, or R&R was avoided by Mrs. Lawrence.

    It was and is no surprise that Mr. Kelly was not interested in major maintenance projects or expense of the mansion - it was not the driving attraction or frankly desired, for the acquision of the property. Indeed the conception of and theory of maintenance for the regional parks system was well expressed by the architectural consultants in 1963: "With these ideas in mind, the architectural consultants produced basic guidelines for a regional park: low maintenance conservation areas suitable for simple outdoor educational and recreational activities, good roads, ample parking areas, scattered picnic tables and grills, simple but substantial shelters and toilets, and recreation meadows. Park boundaries were to follow existing road and highway patterns, or rivers and railroads--physical lines of demarcation. The team approach of the landscape consultants worked extremely well in this project, producing a whole that was greater than the individual parts, according to an article in Landscape Architecture entitled "The Birth of a Regional Park System" (April, 1963)."

    Who was Mr. Kelly? The County Commissioners created the Department of Regional Parks in 1958 and appointed George E. Kelley, an "experienced parks administrator", with a commission to develop a series of six parks (in the type and style of the Chicago Parks and Cook County Preserve systems). George R. Kemp, a trained forester and civil engineer, supervised work in the field and administered the planning effort. The Department of Regional Parks was separate from the original Bureau of Parks created in 1927, but these groups merged by 1969, along with other departmental groups responsible for related interests such as the county fair and recreation to form the current (as of 90s) Department of Parks, Recreation and Conservation. Truth be told the County was desireous of that tract and area, Mrs. Lawrence acquired it and began building upon it just years before the Bureau of Parks was created, and had completed the cottage portion and was "occupying" as a homestead literally just BEFORE the the Bureau of Parks was an entity of record.

    3. The state roof still had not been remediated above the great hall which is central to the stone mansion (as of mid 2007) The area over the "living room", "great room", "great hall", "grand hall" (and other titles which have been used to describe the space since long before the transfer to the County). The County is fully aware of this, and especially since the investigations and reports of the catastrophe in 2005. The ceiling was replaced yet again before roof repairs had even begun. In 2005 the estimated cost for the roof repairs was a million dollars.

    4. A "quick flip" type face lift (patch, clean, paint) project to open the mansion for tours and events was done and took over a year to complete, some parking gravel and a few toilets. The County was not prepared to engage in the major repairs which were identified AT THAT TIME. Some of the work was done via "hollywood" style tactics as a production of a film project was allowed (released on/about 1976). Additional similar work was done by and for productions in the early or mid 90s, and another film production crew just months prior to the collapse in both the grand hall and the formal dining room.

    5. Early reviews, studies, and investigation reports were ignored; pleas for proper use of grant funds, maintenance procedures, remediation requests and planning likewise ignored. Qualified staff departures. Records "lost".

    6. The authority which holds and maintains the parks suffered major reductions in staff. Reganomics further stressed the economy of the Parks Dept. and thus repairs and maintenance, and priorities - the further deferrals of what should have been done. The Departments "hear no evil, see no evil, speak no evil" approach in avoidance of reserve studies, review by qualified individuals, reliance of unqualified (and often part-time) staff, anything beyond the surface patch approach continued: "ignorance is bliss" as in "if we don't officially 'know' its broke we don't have to fix it".

    By June 1986 the Department Director: "Within the past ten years the number of permanent workers has dropped from about 650 full-time employees to something over 100, through various economies and time-sharing strategies with other county departments. The annual budget is approximately six million dollars, but half of that is returned to the treasury in user fees for certain activities." (certain activities = cultural and staff development/education junkets) Joseph B. Natoli, Director of the Department of Parks, Recreation and Conservation (June 1986). That budget was for the entire department, not just Hartwood Acres.

    Keep in mind in 1993 a tour was $3 per person, in 2005 a tour was $5 per person. The majority of those funds collected are used not for maintenance but the purchase of seasonal decorating, the lighting for decorating, and the other half to overall "cultural activites" and "staff development/education". Fees for the use for verious activites in the mansion was allowed even when first opened (pie and refreshment party for realtors association; etc.). The fees collected rarely even covered the actual costs/expenses of the facilities use (cleanup), didn't begin to cover the "wear and tear" on the facility, utilities, etc. and provides no funding for medium or major repairs, maintenance, or replacement.

    7. FYI McClelland Plastering was hired to install the replacement ceiling following the total collapse. Work on the ceiling accounted for $184,000. Cleaining, restoration and repair costs for the Great Hall's ceiling, furniture, flooring, carpets and other furnishings was totaled to be $257,000. I don't recall the exact date (subsequent to mid 2007), but last I heard work still had not been done to remediate the Slate roof, especially above the Great hall.

    Therefore, the long published and often declared attributions to Ghosts, for the signs of problems with this ceiling (and numerous other concerns with other strucutral concerns and deferred maintenance) are well documented. Prior "repairs" to this ceiling also documented, although perhaps no longer in the "records" of the Department; this becomes more difficult as us old timers die off, and youngster's reliance on internet search engines where non OCR records exist, and where older records remain only in non-electronic form. The statements about there having been no moisture issues contributing to the failure are absolutely false. The stone mansion has many issues regarding deferred and incorrect maintenance and deterioration. The contributing factors facilitating this collapse were numerous, your "hypothesis" as to attribution is flawed.

    And no sir, I have not done plaster "repairs" on this building.

    P.S. The ceiling height of 13' (you mentioned you did not know) in and of itself not of issue. The height of the wall surface finish (coats of incompatible "paints" and the moisture/vapor barrier they created) above the wood paneling on stone and similar incompatible finish materials applied on the exposed surface of the ceiling were of issue (as they usually are), especially in the early decades of "your transition period" of construction. Seasonal decorating by well-meaning staff and volunteers since the acquisition were unknown to the great room during the family's ownership. Ask about the boughs, kissing ball, and other ceiling area decorating, review photos of the earlier years. Point being, there are a multitude of issues, events, etc. that were contributory, and this includes water, conditioning and moisture issues.

    Last edited by H.G. Watson, Sr.; 11-15-2009 at 11:45 AM. Reason: post script addressing unknown to the OP info

  13. #13
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    Default Re: Catostrophic Plaster Ceiling Collapse

    It's great to have a full time reporter on staff.

    Contributing factors notwithstanding,be they ghosties, water or vibrations, the attachment system was inadequate.

    Considering the thousands of pounds of material being carried by smooth nails which only penetrated the joists 1/4", vibrations or not, it was just a matter of time and gravity.

    And that's the issue.


  14. #14
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    Default Re: Catostrophic Plaster Ceiling Collapse

    Ceiling collapse a puzzler

    ‘Tom Keffer, the foundation’s construction manager and superintendent of properties maintenance, said he initially suspected that water damage might have caused the collapse, but he did’nt find any moisture concentration when he examined the ceiling’s remains. He said the building is well maintained.’

    Pittsburgh Post-Gazette * Tuesday August 16th, 2005

    Just quoting from the article I first read. I also quoted Tom Donatelli, who I just got an email from. It is possible Mr. Donatelli and Mr. Keffer were unaware of any maintainence issues.

    If we want to avoid collapses, it is all the more reason for informed inspectors, right?

    Long story short...the ceiling fell - and it could have been avoided.

    Last edited by Philip Lamachio; 11-15-2009 at 04:55 PM.

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    Default Re: Catostrophic Plaster Ceiling Collapse

    Ask how long or what size these nails were, and how many he viewed from various areas of the ceiling (you're missing information) how determined 1/4" penetration, what the ends of these "nails" looked like, how about a picture with a scale, surely he has several. Ask what the gauge or thickness of the metal lath was. Again more pictures may be forthcoming.


    Then make a more generalized request for information about the collapse, investigation, and remediation in a formal FOIA request.

    Also ask how much of the clean-up and restoration was covered by insurance proceeds. If a complete risk management assessment was done and ask for a copy. Ask for all pertaining notes, tables of readings, moisture probes, lab analysis, inspectors, adjusters, and engineer reports and assements instant to the period 8/11/05 to aprox 10/15/05. Also request engineering review, notes, correspondance, and reserve studies and preservationist's reports and recommendations for the earlier time periods previously mentioned.

    Again ask in a formal FOIA request, not a casual email to a shared cross-departmental employee; address to appropriate entity.

    Might cost you a few dollars for the copying fees and postage. If you really want to get the facts, all the facts, you have to follow the right path.

    I can't say too much more on the instant subject.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    Although I can say this: Tack nails used to secure canvas reinforcing fabric in the finish plaster while final finish coats applied, were never intended to provide structural reinforcement. Same for the temporary support tacks for some of the applied mouldings and ornate designs that were not fashioned in-place. The structural attachment for the metal lath is and was something else all together.

    Would it interest you to know that Mrs. Lawrence acquired the property with funds she received following the death of her father ('24), a prominent Construction Firm founder and owner, and former State Senator (William Flinn of Booth & Flinn - Booth retired many years earlier and Flinn bought him out)? Would it further interest you to know that very same company was the builder from 1925-1929?

    You scoff at the "Ghost stories" excuse? The two articles to which you referred (PM & here) the very same director stood in the gothic arch shaking her head immediately following the collapse proclaiming there was no warning, people had just been in the room, and she had no idea what could have happened.

    Continued in her beliefs that swaying and shaking chandilliers are the activites of poltergiests:

    HARTWOOD MANSION (Hartwood Acres Park, Allegheny County) The ghosts of John and Mary Flinn Lawrence have been loitering around their old residence, the The Tudor house, sitting in a 629 acre park, is on the National Register of Historical Sites. John Lawrence seems attached to his room, shutting the door when he wants privacy and pulling little poltergeist type pranks on the staff when they're in there. His presence is felt more than seen in the room. Mary Lawrence has been seen beside mansion visitors, and shakes the chandeliers when displeased. The county superintendent claims she's never experienced anything unusual, but her staff people have. She added that some psychics investigated the mansion and said the spirits leave her alone because they like her. (Pittsburgh Post Gazette "Haunted Hartwood?," October 26, 2006)


    I wouldn't attribute much to the knee-jerk CYA remarks from cross-department county employees, or the jockying for deniability positioning. We got the same from the former Bush administration, from weapons of mass destruction, axis of evil IRAQ to Abu Grav to waterboarding and worse at Gitmo and beyond. It is public record as to the roof; the weather (check NOAA archived reports) it was far from "dry" for the weeks preceding RH great to the point of fog, haze and/or precipitation and temperature swings; failure to maintain, condition building, etc. are indisputable as are the discounting of warning signs and face lift patches.

    Last edited by H.G. Watson, Sr.; 11-15-2009 at 11:11 PM.

  17. #17
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    Default Re: Catostrophic Plaster Ceiling Collapse

    Oh, I don't know about doing all that...

    I prefer to cut through the crap and state the obvious:

    Long story short, ceiling collapsed at point of attachment.

    As for moisture, neither men noted any moisture. If it was wet, it seems that would have been pretty easy to dispute at the time. And pretty dumb to assert for the fact it could be disputed.


  18. #18
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    Default Re: Catostrophic Plaster Ceiling Collapse

    If we wanted to practice forensic evaluations ...

    ... from the photo's, I would conclude the ceiling cracked down the center and then peeled from CJ's as remaining fasteners were overloaded. I don't see pull through of the fasteners in the sheets of ceiling laying on the floor as would be evidenced by breakout of base coat on the back of ceiling that fell so I would concur that fasteners pulled out rather than ceiling became detached from fasteners.

    ... from prior experience with plaster ceilings and buildings of this era, attachment of fixtures to framing members is not common (although could happen). Since Chandelier appears to be on the floor under the fallen ceiling and there is a puncture of the ceiling, I would suggest the history of swaying and bouncing Chandelier might lead one to examine attachment of the fixture as a potential crack generator.

    ... again, my experience with buildings of this age would cause me to suspect massive overspan of CJs and this would lead to cracking of plaster along with "testing" of attachments. Overspan of the first floor joists and inattention to wall supports would also be anticipated and could be contributing factors as floors, walls and ceilings flex with changes in loading (not saying visitors to the building caused the failure, simply noting that our current expectations for support and carrying capacity would need to be justified since this building was constructed in another era under a different set of assumptions.)

    ... I note there is substantially more base of plaster "keyed" up past the lath in this type of installation than we would see with a wood lath or gypsum. With a wood lath system, each strip would be nailed off so attachment would be much greater than for a sheet product like either gypsum or expanded metal lath. This may be important as the ceiling weight could be far higher than expected and plasterers familiar with other systems may not be thinking of this if/when switching to a new system. Again, we need to remember our current expectations for code awareness may keep us from thinking in terms of a contemporary worker or construction crew in the 1920s.

    ... in looking at the relatively straight pattern of failure, I would expect the lath sheets were all laid inline rather than staggered. This may have led to a crack in the plaster at the joint between sheets of lath. Alternately, moisture access to the metal lath could have occurred either from the back of the unsealed plaster system (this is essentially a mortar product and the building location lends itself to high ambient humidity). Although I do not see any rusting of the metal lath, I could not rule this out as a potential contributor.

    ... the fibers in one of the pictures do support a contention that the ceiling had a prior crack and this was covered over ... (by a film crew? by a prior owner? who knows from just looking at the photo). Even a small fracture would allow moisture access to lath and if expanded metal lath remained intact across a crack, it would be constantly worked by movement of both ceiling halves further accelerating fatigue.

    ... Plaster installations are subject to the same type of shrinkage and expansion of other concrete installations. The Plaster is a thin coating on a Mortar base. The reason lath is used is as a reinforcement since there is no real tensile strength in either the mortar base or plaster to resist cracking. Cracking typically occurs from bending and shrinkage. From comments re: dancing Chandelier, we can assume bending was occurring by some cause. Unless the building was maintained at a constant temperature throughout its life, we can assume changes in temperature occurred.

    ... water intrusion is a constant issue with plaster systems as there are both chemical and structural bonds that can be effected. Water from a leak would tend to localize and I do not see evidence of this in what is available (just the pictures). The lack of discolorations near the center crack would lead me to suspect high humidity over an active roof leak. I need to keep in mind that moisture seals we think of as standard today are not installed here. Likewise, attic ventilation and insulation were not approached from a standpoint of contributing to structural preservation. This would set up the classic warm side - cold side surface that promotes collection of moisture from the atmosphere. Further, high temperature swings in the attic with moderated temperature swings in the living space would increase physical stresses on the plaster system.

    ---
    So my conclusions based on what has been presented would be that the ceiling cracked initially due to shrinkage and bending stress as would be common for a building of this age.

    The use of expanded metal lath resulted in fewer cracks than would otherwise have occurred.

    The use of expanded metal lath resulted in a heavier plaster system and the use of larger lath pieces allowed installation with fewer fasteners.

    Most likely, the central Chandelier was mounted to the plaster rather than a framing member further adding to the overall weight and multiplied the effect of framing movement on the plaster system.

    Continued movement of the ceiling over time from a variety of causes eventually worked fasteners out near the center crack.

    Covering (so called repair) of the center crack was most likely done with semi flexible materials to resist cracking of the "repair".

    The covering of the initial crack allowed the situation to be ignored until enough fasteners had worked out near the original crack to cause a cascade of additional fastener pullouts.

    ---
    And yes, we should be suspicious of plaster installations ... not because they are inherently unsafe, but because we have learned over time that attention to details makes a large difference in the stability of structures. We have the same inattention to details now as we had then, however, old structures have been tested by time and this aging process takes its toll.

    --- my thoughts.

    Ed Garrett


  19. #19
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    Default Re: Catostrophic Plaster Ceiling Collapse

    @ Ed.

    I have no problem with your evaluation.

    The possiblity of moisture, vibration or other contributing factors leading to the detachment of the nails from the joists are important concerns, and to my mind only emphasize the importance of the attachment system being sound.

    Time and gravity are factors as well, but none of these normal conditions need to have led to collapse, had the attachment system been adequate. (With the exception of major water damage or some unusual construction defect).

    My contention is that more often than not, ceilings of this and similar construction, show signs of failure, and it is a progressive situation because of all the issues mentioned before.

    The real danger of course is for something to occur as did in this situation. The larger lath dimensions along with the inadequate attachment being required to carry the same plaster load as the previous plaster over wood lath is inherently flawed.

    I have seen, and repaired, far too many ceilings like this for each one of them to have been a fluke. There are clear commonalities that lead to similiar problems.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    Looks to me like this ceiling could contain asbestos.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    So, the question I have as a home inspector is what can we look for during an inspection, that would lead us to a conclusion that the ceiling is okay, or that there is danger of eminent collapse? Cracks, sagging, and moisture are the only clues that I can think of offhand. It doesn't sound like any of these were evident in this example however. We have no way of knowing whether or not ring-shank nails were used, or how deeply they might have penetrated into the joists.

    I'm including some photos of a ceiling I ran across during an inspection of a 122 yr. old brick constructed house. It was in dire need of tuckpointing, and water had penetrated to the point that the interior plaster walls in two of the rooms had already separated and fallen off of the brickwork. This ceiling had a series of circular cracks around all corners of the room, and the plaster pegged my moisture meter wherever I checked it. This was an easy call, and such a shame.

    But, if cracks, moisture, or sagging aren't evident (as in this case), is there anything else we can check for that will reveal that a plaster ceiling is not as stable as it should be?

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    Default Re: Catastrophic Plaster Ceiling Collapse

    Quote Originally Posted by Michael Chambers View Post
    This ceiling had a series of circular cracks around all corners of the room,
    I don't see the circular cracks you are referring to, where there circular cracks in those photos?

    Circular cracks typically indicate large loose areas.

    and the plaster pegged my moisture meter wherever I checked it. This was an easy call, and such a shame.
    That part of the easy call was, hopefully, that the plaster was plaster on metal lath ... because that is precisely what metal lath will do - peg a moisture meter.

    But, if cracks, moisture, or sagging aren't evident (as in this case), is there anything else we can check for that will reveal that a plaster ceiling is not as stable as it should be?
    What I used (and used it for other purposes too) was one of those laser square devices which put out a laser line (a laser pointer will only work for this if you are tall enough to reach the ceiling). The laser line is straight, but when shown onto a surface you can see the contour of the surface as a curving line.

    Using that for a sagging ceiling results in a curved line along the sagging portion.

    Mine is a much older version of something like this: Mark2LC - Dual Beam Horizontial and Vertical - Chalk-Line Lasers

    This might also do the same thing as what you really need is a 'laser chalk line': MAGNETIC TORPEDO - LASER LEVEL - Chalk-Line Lasers

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Catastrophic Plaster Ceiling Collapse

    Quote Originally Posted by Jerry Peck View Post
    I don't see the circular cracks you are referring to, where there circular cracks in those photos?

    Circular cracks typically indicate large loose areas.
    You can see one end of a crack in the third photo, the one with the birds in it, bisecting the two lower left fronds. I think this was one of the additional cracks that were also in this ceiling. Unfortunately, I didn't record the circular crack pattern (lesson learned there). I do recall is distinctly however. It was like someone had drawn a large circle inside a square - the square being the whole ceiling in that room.

    Quote Originally Posted by Jerry Peck View Post
    That part of the easy call was, hopefully, that the plaster was plaster on metal lath ... because that is precisely what metal lath will do - peg a moisture meter.
    Nope, what was visible was all wood lathe construction. What I was reading was moisture. As I mentioned, the plaster on the inside of the exterior walls of two of the rooms had already fallen off, and the brickwork underneath was saturated with moisture.

    Quote Originally Posted by Jerry Peck View Post
    What I used (and used it for other purposes too) was one of those laser square devices which put out a laser line (a laser pointer will only work for this if you are tall enough to reach the ceiling). The laser line is straight, but when shown onto a surface you can see the contour of the surface as a curving line.

    Using that for a sagging ceiling results in a curved line along the sagging portion.
    This particular house probably had 10-12 ft. ceilings, but hey, I had to use a ladder to take the moisture readings. I can do the same with a laser line. Good information Jerry! Thanks! I'll definitely be looking into getting and using a laser for this in the future.


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    Default Re: Catastrophic Plaster Ceiling Collapse

    Quote Originally Posted by Michael Chambers View Post
    This particular house probably had 10-12 ft. ceilings, but hey, I had to use a ladder to take the moisture readings. I can do the same with a laser line. Good information Jerry! Thanks! I'll definitely be looking into getting and using a laser for this in the future.

    I've used my laser chalk line (not to be confused with a laser pointer) on 14' and higher ceiling, the problem is that your angle to the ceiling decreases, so the curvature of the laser chalk line decreases too - but you can still see that the line is 'not straight'.

    Jerry Peck, Construction / Litigation Consultant
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  25. #25
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    Default Re: Catostrophic Plaster Ceiling Collapse

    Quote Originally Posted by Michael Chambers View Post
    So, the question I have as a home inspector is what can we look for during an inspection, that would lead us to a conclusion that the ceiling is okay, or that there is danger of eminent collapse? Cracks, sagging, and moisture are the only clues that I can think of offhand. It doesn't sound like any of these were evident in this example however. We have no way of knowing whether or not ring-shank nails were used, or how deeply they might have penetrated into the joists.

    But, if cracks, moisture, or sagging aren't evident (as in this case), is there anything else we can check for that will reveal that a plaster ceiling is not as stable as it should be?
    I thought you just said you found moisture with your meter?

    In any case, you are looking at a plaster over wood lath system, and the most common type of collapse here is to have plaster falling from the wood lath because of broken keys.

    One of the easiest ways I check for unsound plaster is to follow visual inspection ( looking for stains, sagging, cracks) with a very light tapping using either knuckles or some light weight tool.

    Unsound plaster in this system will sound hollow compared to plaster that has not broken away from the keys.

    All plaster over wood lath systems used small smooth nails, but I have never seen 'monolithic' collapse of the whole ceiling due to wood lath attachment failure. Though sections of plaster can fall from the lath, it is not the danger that I am referring to in the orig. post.

    ( I am not saying that some wood won't detach, but because they are small individual laths, they ususally don't affect the next wood lath or cause monolithic collapse)

    The concern in the original post is related to buildings of a later era that use larger monolithic lath systems of metal mesh or gypsum. In those ceilings, the whole lath sections are detaching from joists. If you want to know how to detect those, let me know. I think I posted it on one of the other forums. Need to make sure I have a page for home inspectors to determine just that on my website.

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    Default Re: Catostrophic Plaster Ceiling Collapse

    Quote Originally Posted by Philip Lamachio View Post
    I thought you just said you found moisture with your meter?
    When I asked that question, I was referring to your example, not mine.

    Quote Originally Posted by Philip Lamachio View Post
    One of the easiest ways I check for unsound plaster is to follow visual inspection ( looking for stains, sagging, cracks) with a very light tapping using either knuckles or some light weight tool.

    Unsound plaster in this system will sound hollow compared to plaster that has not broken away from the keys.
    That makes sense, with emphasis on "very light" in the case of a ceiling.


    Quote Originally Posted by Philip Lamachio View Post
    The concern in the original post is related to buildings of a later era that use larger monolithic lath systems of metal mesh or gypsum. In those ceilings, the whole lath sections are detaching from joists. If you want to know how to detect those, let me know. I think I posted it on one of the other forums. Need to make sure I have a page for home inspectors to determine just that on my website.
    If it's something in addition to tapping for a hollow sound, yes, it would be helpful.

    Good input, thanks!


  27. #27
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    Default Re: Catostrophic Plaster Ceiling Collapse

    Michael,

    I put together a page for home inspectors (though it still needs some tweaking) to enable them to identify plaster/gypsum/metal lath systems (I call them 'transitional' ceiling systems) and determine their relative soundness.

    Please visit my website and let me know if it helps. I am open to suggestions on how to communicate this better. (I will be adding photographs later for clarification.)

    Regards,
    Philip Lamachio
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    Thumbs up Re: Catostrophic Plaster Ceiling Collapse

    VERY nice site.
    Great keywords and meta content.
    You know your stuff.


  29. #29
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    Default Re: Catostrophic Plaster Ceiling Collapse

    Thanks Damon, its a work in progress. Let me know of any content I can provide that would be helpful to you as a home inspector.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    Sorry, I am not a home inspector.
    I like reading the posts here because there are some real smart people here, like Jerry and the other top posters.
    My experience is 20 years in the asbestos field.
    Thanks for the compliment though.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    Quick drive by during the late fall migration south.

    Ed (pun intended) nailed it!! Could have been citing directly from reports and evaluations (both pre-collapse prior improper work and post collapse)!

    Yes the mansion spent summers unconditioned while they conducted tours. Yes the mansion is a stone mansion, built with 1920s systems and design, natural ventillation and heating system was modified by ill-informed parks staff during the immediate post-"energy crisis" days of the later part of the Ford Administration and the Carter Administration - these alterations to the vitrified air system added to moisture problems within the structure. The efforts at reducing the utility costs for the structure and preventing air infiltration/exchange actually caused and continue to cause more problems.

    Yes the manion spent and spends the major portion of the winter system less than ideally heated - it is shut down following the winter holiday season display and doesn't reopen until Spring. When occupied as a residence the mansion was heated and ventillated throughout the Winter season.

    The circular void in the collapsed ceiling was the location of a chandiller. Yes this and other zones had been previously and improperly "repaired" many times, and yes concentrations and the effects of MC and RH and condensation were apparent.


  32. #32
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    Default Re: Catostrophic Plaster Ceiling Collapse

    I try to educate my customers (who probobly have more pressing things on their minds) about the need to maintain reasonably stable humidity and temperature levels since plaster and wood expand/contract at different rates (does plaster expand/contract at all? My guess is it is minimal) leading to broken keys.

    I don't think that there is any question though, that in this case, it was an attachment system failure, regardless of possible overspan.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    Philip;

    Yours is indeed a useful and informative website. I learned some things there. I wasn't aware that a failing plaster ceiling could be repaired. The photos I posted were of a first floor ceiling on a two story house (there is no attic access). Could something like that be repaired as well? I attributed the circular cracking pattern in that ceiling to flexing of the central area of the ceiling due to regular traffic in the second floor bedroom above. I don't know how you could stop that from occurring. This was of course a 122 yr. old wood lathe system.

    What little I know about the later transitional gypsum lathe system includes that the sections were smaller than todays 4x8 or 4x10 drywall, and the edges weren't tapered. Is that correct? I've bookmarked your website for future reference. Thanks!

    Mike


  34. #34
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    Default Re: Catostrophic Plaster Ceiling Collapse

    @ Michael Chambers

    'attributed the circular cracking pattern in that ceiling to flexing of the central area of the ceiling due to regular traffic in the second floor bedroom above. I don't know how you could stop that from occurring'
    You can tear out the loose plaster in that area and make sure wood lath is secure and re-plaster, or add screen mesh over and plaster to cover it.

    If the joists are flexing and causing the cracks, you might slow down the cracking this way.

    But you should test the plaster for soundness by tapping solid plaster and then the affected area. If it gives a hollow sound you might want to replace the plaster bc. the keys may have broken.

    What little I know about the later transitional gypsum lathe system includes that the sections were smaller than todays 4x8 or 4x10 drywall, and the edges weren't tapered. Is that correct?
    Early gyp lath was in smaller sections, later was larger. The larger sections present a more dangerous scenario, from what I have seen.

    Right, the edges weren't tapered. That seems to have been developed to hide the tape and mud when modern drywall methods were introduced.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    Quote Originally Posted by Philip Lamachio View Post
    You can tear out the loose plaster in that area and make sure wood lath is secure and re-plaster, or add screen mesh over and plaster to cover it.

    If the joists are flexing and causing the cracks, you might slow down the cracking this way.

    But you should test the plaster for soundness by tapping solid plaster and then the affected area. If it gives a hollow sound you might want to replace the plaster bc. the keys may have broken.
    Take a look at the photos I uploaded in post #21 of this thread. This is the ceiling I've been referring to. Re-plastering is not an option - and the loss of such a ceiling is such a shame.


    Quote Originally Posted by Philip Lamachio View Post
    Early gyp lath was in smaller sections, later was larger. The larger sections present a more dangerous scenario, from what I have seen.

    Right, the edges weren't tapered. That seems to have been developed to hide the tape and mud when modern drywall methods were introduced.
    That's my understanding as well. Thanks for your posts on this.


  36. #36
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    Default Re: Catostrophic Plaster Ceiling Collapse

    Take a look at the photos I uploaded in post #21 of this thread. This is the ceiling I've been referring to. Re-plastering is not an option - and the loss of such a ceiling is such a shame
    Yeah, I saw the detail. It still may be able to be saved.

    HG Watson posted a link showing another way to secure loose plaster in a plaster over wood lath system. It is on the first thread I started.

    I haven't actually used this method, which involves drilling holes, vaccuming out dust and debris and injecting adhesive, but then again, I haven't had a job that saving decorative plaster was an issue.


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    Default Re: Catostrophic Plaster Ceiling Collapse

    That reminds me of a drywall contractor when I was building in San Antonio. I was complaining to him that his installers did not properly nail the drywall. I insisted that on the homes I built, he and I would inspect the nailing before any finishing was done. The other superintendents didn't have a problem with him.

    I was helping one of the other supers get a home ready to close the next day and as we were looking around, he mentioned to me that the buyers had already mentioned that this one particular room was going to be the nursery. When we got to work the next day, a full 4 X 8 sheet of drywall was laying on the floor in that room. We counted a total of 9 nails in that board. 3 of them had missed the ceiling joists! Needless to say, the home did not pass inspection and did not close that day.

    The other supers started paying closer attention to drywall nailing too.

    Robert Sole
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    www.REMinspections.com, Orlando, Oviedo

  38. #38
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    Default Re: Catostrophic Plaster Ceiling Collapse

    Guys were working too fast...trying to make some $$$$. I bet they cut up and threw away 1/3 of the drywall bought for the job too.

    BTW, why are they using nails anyway? When the hammer hits the nail and indents the paper, doesn't that break the bond between the gypsum and the paper?

    Also, wouldn't screws be better since they don't back out? (as long as you don't break the paper)

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    Default Re: Catostrophic Plaster Ceiling Collapse

    Quote Originally Posted by Philip Lamachio View Post
    Guys were working too fast...trying to make some $$$$. I bet they cut up and threw away 1/3 of the drywall bought for the job too.

    BTW, why are they using nails anyway? When the hammer hits the nail and indents the paper, doesn't that break the bond between the gypsum and the paper?

    Also, wouldn't screws be better since they don't back out? (as long as you don't break the paper)

    Philip LaMachio
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    Screws also prevent the ubiquitous nail pops we see all the time as well.

    Hey, thanks for providing the link to the article that HG Watson posted as well. I wish I'd had that article when we were trying to figure out how to save that painted ceiling. It probably would have kept that house sale from falling through.


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    Default Re: Catastrophic Plaster Ceiling Collapse

    Quote Originally Posted by Philip Lamachio View Post
    BTW, why are they using nails anyway? When the hammer hits the nail and indents the paper, doesn't that break the bond between the gypsum and the paper?
    Using the proper drywall hammer ( Estwing Drywall Hammers ), which has a rounded face to make the proper dimple in the drywall, that is not a problem.

    Also, wouldn't screws be better since they don't back out? (as long as you don't break the paper)
    Also, nails spacing is closet together than screw spacing, which also helps reduce the nails backing out as there are more nails which have less weight per nail, or use double nailing which keeps the same spacing as screws and which also provides for more nails with reduced load be nail.

    Jerry Peck, Construction / Litigation Consultant
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  41. #41
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    Default Re: Catostrophic Plaster Ceiling Collapse

    agreed with Jerry Peck.nice reply


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