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  1. #1
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    Question OSB exposed to the weather

    New construction: Dried in single family home built 1 year ago with OSB exterior sheathing is now being wrapped with tyvek and bricked no interior work done yet.
    What are the inherent issues that may arise out of this? If any. My initial thought is the OSB has been exposed to the elements and could have issues of moisture and or failure to hold nails. Our county does not have a building code, and this is in the county.
    Your thoughts would be greatly appreciated.

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  2. #2
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    Default Re: OSB exposed to the weather

    OSB can start to disintegrate when exposed to moisture and UV rays. I would have it examined closely and replace any affected areas before covering. OSB provides sheer strength to keep the house from racking. If nails can pull through or the wood buckle, you can have severe structural issues for the entire house, not just the wall section. All in all OSB is pretty durable but it is not designed for exterior exposure.

    Jim Luttrall
    www.MrInspector.net
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    Default Re: OSB exposed to the weather

    I've seen houses/buildings around here sit with the OSB exposed for several years and then finished. It's certainly not ideal and I don't specifically know the long term performance. I mainly mention it just let you know it's been allowed around here and we do have a building code.


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    Smile Re: OSB exposed to the weather

    Thanks for the help guys.


  5. #5
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    Default Re: OSB exposed to the weather

    I would be more concerned with the studs, sill plates and band sills. The OSB will tend to hold up fairly well to the elements as compared to the dimensional lumber. The extent of damage depend on a couple of factors, where the windows installed or not while it sat? Did the sheathing extend all the way to the bottom of the band sill?

    You have a big advantage in discovering any problems before the house is bricked or drywall is hung, check it all very closely and make sure it is dry (with a moisture meter) before you cover anything up.

    David, I just realized that you are an inspector and not the homeowner,(I can't insert the embarrassed smiley while editing) my apologies for the tone of the post.

    Last edited by chris mcintyre; 02-06-2010 at 02:59 PM. Reason: add apology

  6. #6
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    Default Re: OSB exposed to the weather

    Chris,
    All those are good points to consider. No apology necessary.
    The house has been dried in for about a year. It doesn't appear that there are abnormal signs of water or moisture on the inside in the areas you mention. The physical examination of the OSB from the outside showed no visible signs of deterioration or delamination.
    When going to the homeowner, how or what do I delineate on my inspection report. "Exterior sheathing appears to have been exposed to the weather for some time and shows signs of wear, recommend further investigation by a licensed contractor to determine .....? what?
    I don't feel I can go to homeowner and tell them that there is an issue if I can't document it for them, or give them reasons for my concern. I certainly do not want to be an alarmist.


  7. #7
    Ted Menelly's Avatar
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    Default Re: OSB exposed to the weather

    There is a lot to consider with any home that has been partially constructed and left exposed for a year. Not just the OSB. There is no being an alarmist expressing such to a buyer of a piece of property. How much has happened to the OSB? How rusted are the nails holding the OSB? What condition are the studs in the rest of the home being wet and dried for so long? What is the water content in all the wood of this home?
    Twisted studs? Twisted headers? Is the studs in the home fingered studs and have they been exposed to water and sunlight?

    Lots and lots of questions. There is so much we can determine but depending on the circumstances and severity of weather this home has been exposed to it may need further looking into. What about engineered lumber, floor joists etc etc.

    Lots and lots to consider.


  8. #8
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    Default Re: OSB exposed to the weather

    Quote Originally Posted by David D. Whitt View Post
    Chris,
    All those are good points to consider. No apology necessary.
    The house has been dried in for about a year. It doesn't appear that there are abnormal signs of water or moisture on the inside in the areas you mention. The physical examination of the OSB from the outside showed no visible signs of deterioration or delamination.
    When going to the homeowner, how or what do I delineate on my inspection report. "Exterior sheathing appears to have been exposed to the weather for some time and shows signs of wear, recommend further investigation by a licensed contractor to determine .....? what?
    I don't feel I can go to homeowner and tell them that there is an issue if I can't document it for them, or give them reasons for my concern. I certainly do not want to be an alarmist.
    David, you simply need to tell your client the following, it is simple and to the point. I have used it several times already this year:

    This unfinished home has been exposed to the weather for an extended period of time. Building products such as OSB sheathing and wood framing are not designed to be exposed to the weather unprotected for lengthy periods of time. Although the materials look solid, I have no way of knowing what or how this is going to impact the home once it is finished.

    You are telling your client what you know and don't know. Recommending further "evaluation" won't do anything for anyone. This is all that really needs to be said.

    Scott Patterson, ACI
    Spring Hill, TN
    www.traceinspections.com

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    Default Re: OSB exposed to the weather

    I can't find it right now, but I recall having had a letter or some other document from the APA stating that OSB (and plywood, Exposure 1) is suitable for being left exposed "during construction operations" and "up to 6 months".

    Quite obviously, that OSB was left exposed outside the activities of "during construction operations" and quite a while beyond the "up to 6 months) time frame.

    Jerry Peck, Construction / Litigation Consultant
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  10. #10
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    Default Re: OSB exposed to the weather

    OSB used to be allowed to be used as a water-resistant barrier (2003 IRC and earlier). Then the APA determined that the repellant they applied (the slick side) wasn't near as water-resistant as they thought. If OSB is used on the exterior side of the walls, then a water-resistive barrier must be applied. The normal Tyvak that you see installed is not water-resistive so you may need to look at that also.

    Just my thoughts.


  11. #11
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    Post Re: OSB exposed to the weather

    In addition to the weather exposure the brick over Tyvek is a real concern. Tyvek is very vapor permeable and brick will create a hugh vapor drive into the OSB that will accelerate OSB deterioration. This is especially true of brick veneers or cultured stone. Cement siding can cause the same problem in certian circumstances.

    Proper installation should include a space between the OSB and the veneer, brick or stone. Two layer "Drainage Space" weather barriers have just been introduced to the market by several manufacturers. Oregon State code now requires these behind stucco, cultured stone and brick veneers.

    Just a heads up - good luck!


  12. #12
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    Default Re: OSB exposed to the weather

    Manufactured wood products, made of glue and wood fiber, can swell and lose strength in moisture. "They can actually turn to kind of mush if they get too wet too often," says Claudette Reichel, an expert on housing and building materials at the Louisiana State University Agricultural Center. The warranties and manufacturer recommendations vary on different products, but generally two months roughly the time it takes to get a house ready to enclose is their exposure limit, Carlysle says. Oriented strand board (OSB) used in floors, roofs and walls, can grow mold in a week or less under the right conditions, causing ugly stains and a health hazard. Plywood thin, laminated sheets of wood pressed together with glue will separate and warp. (Warped wood is unsightly but structurally sound.) "It's basically rated for exposure during the construction period and that's all," Carlysle says. "If it sits on the site for a month or so before the building gets started, then that clock is running."

    Additionally, all OSB manufacturers require that all cut edges be resealed immediately. Yeah, right . . .


  13. #13
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    Default Re: OSB exposed to the weather

    Quote Originally Posted by A.D. Miller View Post
    Manufactured wood products, made of glue and wood fiber, can swell and lose strength in moisture. "They can actually turn to kind of mush if they get too wet too often," says Claudette Reichel, an expert on housing and building materials at the Louisiana State University Agricultural Center. The warranties and manufacturer recommendations vary on different products, but generally two months — roughly the time it takes to get a house ready to enclose — is their exposure limit, Carlysle says. Oriented strand board (OSB) used in floors, roofs and walls, can grow mold in a week or less under the right conditions, causing ugly stains and a health hazard. Plywood — thin, laminated sheets of wood pressed together with glue — will separate and warp. (Warped wood is unsightly but structurally sound.) "It's basically rated for exposure during the construction period and that's all," Carlysle says. "If it sits on the site for a month or so before the building gets started, then that clock is running."

    Additionally, all OSB manufacturers require that all cut edges be resealed immediately. Yeah, right . . .
    The whole article was my post above. Two many things to consider once a home has been exposed to the elements for long periods of time.

    As I said....An alarmist. Not in the slightest. To long an exposure and two many questions. It would be a serious consideration to have a structural engineer to look at the home. Being very familiar with all these structural components he is far more likely to have all the info readily available for the clients.

    We as home inspectors are pretty much...The inspection is done...a review of our inspection...done. To get that deep into checking out exposure rates and concerns from such needs to go off to the next ...dig a lot deeper.....professional.

    Unless of course there is some further deal made for such an in depth inspection and review of all materials.

    Engineered lumber,trusses, sheathings, floor joist etc etc in todays construction are far more involved with problems that can arise from a wide array of circumstances.

    How about the fact that homes collapse much faster than conventionally framed homes (from fires or floods or water from putting out a fire). Why, because of all the compressed glued up materials being penetrated by heat and water. Far fewer homes are saved today than the ones built years ago.

    Last edited by Ted Menelly; 02-08-2010 at 01:06 PM.

  14. #14
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    Smile Re: OSB exposed to the weather

    Jerry,
    I found the publication to which you refer. APA - The Engineered Wood Association
    Search for OSB will result in a column of information. The publication below is the one I dowloaded, and yo are correct on the exposure types.
    Oriented Strand Board
    Describes OSB composition, properties, code acceptances, and applications. Revised February 2009. Printed version available August 2009. (Form W410 - 12 pages)

    Wayne,
    If you could get me the section out of the book, i can't find where, "If OSB is used on the exterior side of the walls, then a water-resistive barrier must be applied." Was that from the IRC or the APA?? I went to Duponts website and they seem to think that the Tyvek product is of a non permeable product. The test results from third party organizations had tested Tyvek and found it to be quite effective for a moisture barrier.

    What I concluded is that I was asked for my professional opinion on the home being constructed. With the information you all provided, helped me in determining a course of action.
    I subsequently used some of what Scott replied in his post and also provided the APAs 12 page document to the homeowner. I realized that I needed to provide the client with as little of confusing information as possible. The document from the APA, which is a third party article from a professional organization, along with the general results of a visible inspection allowed them to be reassured that they could move forward.
    Since then I have discussed the information with the builder, with the approval of my client, what I saw and also gave him the information I provided to the client. He said as much that he appreciated that I went the extra mile, and that he would always stand behind his construction.

    Thank you very much for all your input, many blessings.


  15. #15
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    Default Re: OSB exposed to the weather

    David

    SECTION R703
    EXTERIOR COVERING
    R703.1 General.
    Exterior walls shall provide the building
    with a weather-resistant exterior wall envelope. The exterior
    wall envelope shall include flashing as described in Section
    R703.8. The exterior wall envelope shall be designed and
    constructed in a manner that prevents the accumulation of
    water within the wall assembly by providing a water-resistant
    barrier behind the exterior veneer as required by Section
    R703.2. and a means of draining water that enters the assembly
    to the exterior. Protection against condensation in the
    exterior wall assembly shall be provided in accordance with
    Chapter 11 of this code.


    OSB is not weather-resistant




  16. #16
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    Default Re: OSB exposed to the weather

    DW:

    From:

    http://www.apawood.org/pdfs/managed/...TOKEN=58718279

    2. All panels which have any edge or surface exposed long term to the weather shall be classed Exterior.

    Sheathing exposed long term to weather shall be classed Exterior.

    A. Preparation of Surfaces
    1. Exterior Panels Panels to be exposed outdoors shall have all edges sealed. With paint, sealer may be a liberal coat of exterior house paint primer. With stain, seal with water-repellent preservative compatible with finish coat.


  17. #17
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    Default Re: OSB exposed to the weather

    Quote Originally Posted by A.D. Miller View Post
    DW:

    From:

    http://www.apawood.org/pdfs/managed/...TOKEN=58718279

    2. All panels which have any edge or surface exposed long term to the weather shall be classed Exterior.

    Sheathing exposed long term to weather shall be classed Exterior.

    A. Preparation of Surfaces
    1. Exterior Panels Panels to be exposed outdoors shall have all edges sealed. With paint, sealer may be a liberal coat of exterior house paint primer. With stain, seal with water-repellent preservative compatible with finish coat.
    I looked at the publication and from what I read, the specification is referring to 19/32 rated panel siding Pg 17 not OSB.

    Quote Originally Posted by Wayne Carlisle View Post
    David

    SECTION R703
    EXTERIOR COVERING
    R703.1 General.
    Exterior walls shall provide the building
    with a weather-resistant exterior wall envelope. The exterior
    wall envelope shall include flashing as described in Section
    R703.8. The exterior wall envelope shall be designed and
    constructed in a manner that prevents the accumulation of
    water within the wall assembly by providing a water-resistant
    barrier
    behind the exterior veneer as required by Section
    R703.2. and a means of draining water that enters the assembly
    to the exterior. Protection against condensation in the
    exterior wall assembly shall be provided in accordance with
    Chapter 11 of this code.


    OSB is not weather-resistant

    So once the tyvek is applied, a water resistant barrier will have been applied, thanks.


  18. #18
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    Default Re: OSB exposed to the weather

    DW:

    From:

    http://www.rci-online.org/interface/...ton-murphy.pdf

    Analysis conducted by NIST and ORNL clearly indicates a significant difference in moisture exchange performance of OSB and plywood in wet conditions. The extended periods of increased moisture content observed in the OSB panels can be expected to result in significantly exacerbated conditions of mold growth and wood rot. In wet conditions, the OSB will experience, over time, a much greater potential for severe structural deterioration.

    And your point was?


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    Wink Re: OSB exposed to the weather

    Quote Originally Posted by A.D. Miller View Post
    DW:

    And your point was?
    When I am given data taken from a source, I always want to know the context in which the said data was referenced. I researched both articles from which you sent data and I wanted to clarify the information. That is what your quote sais, yes? Take everything with a salt block until you can research it and have a clear understanding of its truth.

    "What the plainspoken man lacks in subtlety he makes up in clarity." - A.D. Miller

    Thank you for taking time to post those articles. They are now in my file.


  20. #20
    Ted Menelly's Avatar
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    Default Re: OSB exposed to the weather

    Yeah yeah, I know

    Books good

    articles good

    read gain knowledge good

    so what's my point

    I always try to figure out why no one on hear, almost no one, talks of personal, knowledgeable experience. Everything talked about is known with out delving into books and who wrote it and what kind of study was done and how long the study was and who is this guy anyway, how good is the source, what does he have to back it up etc etc et etc.

    Does no one on the planet have any personal background knowledge of anything anymore.

    I am not knocking any particular individual or individuals but ....what was that say....."just asking" or "just saying"

    Other thread. I know from going into countless attics that it is always cooler in an attic when it has eve and gable vents with central roof top venting added. As simple as it gets. It is always cooler than the home next door with no centralized venting. Does no one know this from personal experience. Everyone talked about studies and air exchange ,,,,,,,,and yes I understand the quest for knowledge but has no one ever just went into an attic after going into an identical attic and said "man, it sure feels cooler in here, and then you look up and see there is central roof top vents or split in thirds with turbine vents. Who cares what a book or case studies say....It's cooler.

    All this exposed OSB, engineered floor joist and finger jointed studs etc etc etc . Has no one ever witnessed the mold, the expansion, done a test for moisture content, covered Sheathing with Tyvek and see what a big difference there is in later years of the home with and the home without it or any type of wrap for a home. Have you read articles about the destructive nature of sunlight , water freezing in lumber and engineered sheathing and lumber, no sheathing on the studs to hold it square or drywall on the interior to help keep it from bowing, OSB floor decking exposed to the elements for long periods of time and and and

    Just saying!

    Everything above is basic construction knowledge 101...well...some 102


  21. #21
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    Default Re: OSB exposed to the weather

    Quote Originally Posted by Ted Menelly View Post
    I always try to figure out why no one on hear, almost no one, talks of personal, knowledgeable experience.

    Personal experience? WE DO talk about it, but ... if you want supporting documentation, TALK is not worth diddly-squat, MANUFACTURER'S DOCUMENTATION is, PRODUCT APPROVAL is, and all those other things which can be pulled in a courtroom and put forth as 'these here pages was writ by people whole lots smarter den me is'.

    Jerry Peck, Construction / Litigation Consultant
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    Wink Re: OSB exposed to the weather

    I feel very lucky to be able to come to a message board, ask a question, and get responses from professional home inspectors with varying backgrounds and education levels.
    I always remember that:

    "A home inspection is a non-invasive visual examination of a residential dwelling, performed for a fee, which is designed to identify observed material defects within specific components of said dwelling. Components may include any combination of mechanical, structural, electrical, plumbing, or other essential systems or portions of the home, as identified and agreed to by the Client and Inspector, prior to or during the inspection process."

    "A home inspection is intended to assist in evaluation of the overall condition of the dwelling. The inspection is based on observation of the visible and apparent condition of the structure and its components on the date of the inspection and not the determination of future conditions."

    " A home inspection will not reveal every problem that exists or ever could exist, but only those material defects observed on the day of the inspection."


    "I will learn until I die!" DW


  23. #23
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    Default Re: OSB exposed to the weather

    (see note below regarding the words in red)
    Quote Originally Posted by David D. Whitt View Post
    I always remember that:

    "A home inspection is a non-invasive visual examination of a residential dwelling, performed for a fee, which is designed to identify observed material defects within specific components of said dwelling. Components may include any combination of mechanical, structural, electrical, plumbing, or other essential systems or portions of the home, as identified and agreed to by the Client and Inspector, prior to or during the inspection process."

    "A home inspection is intended to assist in evaluation of the overall condition of the dwelling. The inspection is based on observation of the visible and apparent condition of the structure and its components on the date of the inspection and not the determination of future conditions."

    David,

    Don't put any faith in relying that "visual"/"visible" smoke screen.

    As soon as you pull out a flashlight, or a screw driver, or an outlet tester, or ANYTHING other than your eyes, you have exceeded the "visual" boundaries and are now on your own into whatever is it you personally establish as your level of inspection.

    The "limited visual" aspect of home inspections went out decades ago.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  24. #24
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    Default Re: OSB exposed to the weather

    Quote Originally Posted by Ted Menelly View Post
    I always try to figure out why no one on hear, almost no one, talks of personal, knowledgeable experience.
    Does no one on the planet have any personal background knowledge of anything anymore.
    I do!. I do! Sheesh I didn't think anybody would want to hear my personal thoughts and experiences, but since you've asked ..........
    A guy I was working with in the 80's had built a storage shed on rented property from unpainted OSB and Hemlock 2X4 studs. When he moved he offered the shed to me. We knocked it apart into 4 foot sections, that's how he had built it, 4X8 wall sections. We loaded the panels into my 3/4 ton Chevy and they weighed a ton. I used them to build a cabin on a foreshore lease that I had at the time, that was then, this is now. I used plywood for the roof and gave it a proper 18" or more overhang all around so the walls stayed pretty dry.
    That cabin stood on piers above the high tide mark for at least ten more years without paint of any kind. It just turned a silver grey color. It must have been too cold and damp out there for mould, because mold never grew on those walls.
    What does that have to do with this post? Nothing.

    Covering damp OSB and sealing it up behind drywall is asking for trouble. I would demand moisture tests.


  25. #25
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    Default Re: OSB exposed to the weather

    Quote Originally Posted by Jim Luttrall View Post
    OSB can start to disintegrate when exposed to moisture and UV rays. I would have it examined closely and replace any affected areas before covering. OSB provides sheer strength to keep the house from racking. If nails can pull through or the wood buckle, you can have severe structural issues for the entire house, not just the wall section. All in all OSB is pretty durable but it is not designed for exterior exposure.
    "Someone left a cake out in the rain"

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  26. #26
    Bob Barnett's Avatar
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    Default Re: OSB exposed to the weather

    Quote Originally Posted by David D. Whitt View Post
    New construction: Dried in single family home built 1 year ago with OSB exterior sheathing is now being wrapped with tyvek and bricked no interior work done yet.
    What are the inherent issues that may arise out of this? If any. My initial thought is the OSB has been exposed to the elements and could have issues of moisture and or failure to hold nails. Our county does not have a building code, and this is in the county.
    Your thoughts would be greatly appreciated.
    Moisture , mold, deterioration. This sheathing should be replaced IMO. Whenever we built our houses, it was immediatley wrapped to protect it from, the elements. Usually this was within a week or so. We knew if we did not, it was only time before we had return calls for molds and rot.


  27. #27
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    Default Re: OSB exposed to the weather

    I would say the structure should be inspected by a structural egineer with the proper experience.

    Beside the posible material failure I would be concerned about the condition of any fastners from either corrision or from excessive material expansion due to moisture and freezing conditon.

    The brick should have a proper drainage plane/air space. A plastic mesh made for this or at least a double layer of a house wrap.


  28. #28
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    Default Re: OSB exposed to the weather

    Sounds pretty simple, why all the rocket science?
    1) State issue-Sheathing exposed to weather longer than manufacturer recommends.
    2) Cite reference-APA product usage data sheet.
    3) Submit report and move on.

    Chances are that this house, if allowed to finish as is, is in for serious issues down the road, but recommendations are not your job. A simple "If it were my house..." should do nicely. Someone has to take responsibility for proceeding here, your job is to provide facts sufficient to inform that decision, not opinion on what to do.

    I'm a dyslexic agnostic-Don't believe there is a dog...

  29. #29
    Leigh Goodman's Avatar
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    Default Re: OSB exposed to the weather

    " Our county does not have a building code, and this is in the county.
    Your thoughts would be greatly appreciated." (from original post)

    I hear that a lot in my rural area of Kentucky, but it is a misstatement here and I am guessing that it may be a misstatement where you are.
    We have no code enforcement by a local authority. However, the state building code applies and tradespeople are expected to follow it. You will not get any inspection but electrical.

    If someone demonstrates later that you have not followed the state building code you will not have the defense that there is no code in my county.
    Big difference between no code and no local enforcement agency. A judge can enforce the code for the county.


  30. #30
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    Default Re: OSB exposed to the weather

    I just wanted to see my name on all the issues here.

    I'm a dyslexic agnostic-Don't believe there is a dog...

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