Thread: Attic sheathing

Hello all,

I found delamination on the sheathing in an attic only in one section.
The bathroom vents vent to the outside. There is an attic fan.
A moisture check was negative.
I have attached the photo.

Thanks in advance for any help in describing this one

Donald

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Thank You

Originally Posted by Donald H

Hello all,

I found delamination on the sheathing in an attic only in one section.
The bathroom vents vent to the outside. There is an attic fan.
A moisture check was negative.
I have attached the photo.

Thanks in advance for any help in describing this one

Donald

Sure does look like it has been caused by moisture. The rafters even look like they have moisture stains on them.

When was the last time it rained?

Is the attic fan working? Is it on a thermostat or does it have to be turned on manually? Looks to me like improper ventilation in the attic causeing condensation. Just a thought

Hello

There is roof and soffit ventilation. The fan works. The insulation is about double the required amount. I could not walk the attic. I wrote it up as signs of possible previous moisture or condensation. Recommended evaluation.

Donald

Attached is a closer look

Donald

When the striations( 1/4" straight lines) of 'clean' wood are considered, it would seem that some sort of compound was applied and is now peeling off. Is the peeling material actually a wood product, or more like a coating of some paint or rubberized compound? Does the stuff on the rafters come off as a fine dust? Are the missing chips laying on the top of the insulation?

Originally Posted by Donald H

Hello all,

I found delamination on the sheathing in an attic only in one section.
The bathroom vents vent to the outside. There is an attic fan.
A moisture check was negative.
I have attached the photo.

Thanks in advance for any help in describing this one

Donald

Its not a fungus. kind of looks like a lacquer that is now peeling off...

Good luck with it. did you put a moisture meter on it?

Best

Ron

This looks like a roof leak. Is this a flat roof?
How old is this roof sheating. If its not a leak, could the roof sheating be the old fire treated plywood from the late 1970's early 1980"s that charcoals prematurely when temps in the attic reach 140 to 106 degrees?

It does not look like wood delaminating to my eye....more like some product applied to the surface of the ply as others have said...but then there is some bleed onto the rafters. Could the soffit, ridge vents and attic fan have been installed as a remedy for a previous moisture problem caused by the absence of any attic ventilation? How old is the house?

Originally Posted by Robert Foster

....more like some product applied to the surface of the ply as others have said...but then there is some bleed onto the rafters.

An early attempt at a spray on radiant barrier?

I am no expert, always want to start with that.

But "I" have to say that it is simply mildew build up that has now dried up and is flaking off. I see this often enough in different stages.
It is typical when people correct moisture from entering the attic and improve venting. Then don't bother to clean up the roof deck that was covered by mildew or mold growth.

(boy I hope I am right)

Information given in your posts and evidence in your photos is consistent with moisture damage from winter condensation on the sheathing (frost). Further information will help confirm this: 1. What is the age of the house? 2. Is the sheathing better on one side of the attic vs. the other? 3. What side of the house has the worst damage to the sheathing?

I believe you will say that the house was built before 1985, that there is a variation in the damage and that the worst is on or near the north. If so, this is frost induced damage which comes from warm air leaking into the attic from penetrations for wiring and plumbing. (aka Attic Bypasses). The fact that additional insulation was installed (probably without sealing the bypasses) has made the attic colder and for longer times than the original design of the house. Additional attic ventilation will NOT help. The recommended action would be to REMOVE all existing attic insulation, seal all the attic bypasses, and re-insulate.

I see this condition frequently in Minnesota. The peeling surface is often a mold fungi. If widespread and blackened, there may actually be weakening of the plywood sheathing. You may have felt this if you walked the roof. If the house is also due for a reroofing soon, the strength of the sheathing should be evaluated. It may be necessary to resheath the roof. Cleaning and treating the plywood is not recommended, since the area atop the trusses can't be reached. Notice that the sides of the trusses have fungal darkening also.

For an extreme case, where indoor humidity was way to high, see my website Troubled houses: Photos from award winning Hankey & Brown Inspection Service, Certified ASHI Inspectors in Eden Prairie, MN serving the Twin Cities of Minneapolis-St.Paul & suburbs for over 34 years. and scroll down to the blackened attic photos. There are also other images of this condition further down the page.

Originally Posted by Roger Hankey

Information given in your posts and evidence in your photos is consistent with moisture damage from winter condensation on the sheathing (frost). Further information will help confirm this: 1. What is the age of the house? 2. Is the sheathing better on one side of the attic vs. the other? 3. What side of the house has the worst damage to the sheathing?

I believe you will say that the house was built before 1985, that there is a variation in the damage and that the worst is on or near the north. If so, this is frost induced damage which comes from warm air leaking into the attic from penetrations for wiring and plumbing. (aka Attic Bypasses). The fact that additional insulation was installed (probably without sealing the bypasses) has made the attic colder and for longer times than the original design of the house. Additional attic ventilation will NOT help. The recommended action would be to REMOVE all existing attic insulation, seal all the attic bypasses, and re-insulate.

I see this condition frequently in Minnesota. The peeling surface is often a mold fungi. If widespread and blackened, there may actually be weakening of the plywood sheathing. You may have felt this if you walked the roof. If the house is also due for a reroofing soon, the strength of the sheathing should be evaluated. It may be necessary to resheath the roof. Cleaning and treating the plywood is not recommended, since the area atop the trusses can't be reached. Notice that the sides of the trusses have fungal darkening also.

For an extreme case, where indoor humidity was way to high, see my website Troubled houses: Photos from award winning Hankey & Brown Inspection Service, Certified ASHI Inspectors in Eden Prairie, MN serving the Twin Cities of Minneapolis-St.Paul & suburbs for over 34 years. and scroll down to the blackened attic photos. There are also other images of this condition further down the page.

A quote from your site

"A few days later, a forensic investigator made a cut in the wall and revealed that the leaks at the flashing and windows had led to extensive decay of the wall sheathing behind the brick."

Wow. You use terms like forensic investigator to your clients and potential clients.

Good luck to you. I guess I will start using big words. I usually say that upon further investigation from a contractor (insert type) there was further damage from water penetration.

No digs intended so please don't think I am down on you. I am just more of the down to earth type home inspector that does not blow or hype things up and am always amazed at how some folks are so into the seriousness of home inspection like it is brain surgery. I get all my work for the direct and to the point speak, both verbally and on my reports. I think if I used terms such as forensic investigator I would lose my long following.

With the "clean" lines near the trusses on the underside of the roof decking, likely from shrinkage, and the dark patterns on both the decking and trussess, It looks to me to be delaminating of a coating, possibly clear shellac which may have been applied to seal in and remediate or seal in the odor from prior smoke damage. If a flake disolves in denatured alcohol, that would confirm.

Don't see any markings, chance it might be FRT?

Originally Posted by H.G. Watson, Sr.

With the "clean" lines near the trusses on the underside of the roof decking, likely from shrinkage, and the dark patterns on both the decking and trussess, It looks to me to be delaminating of a coating, possibly clear shellac which may have been applied to seal in and remediate or seal in the odor from prior smoke damage. If a flake disolves in denatured alcohol, that would confirm.

>>I doubt that this is the case. RH

Don't see any markings, chance it might be FRT?

>> I doubt that this is the case. I do not believe FRT plywood was used in many single family homes in Chicago, but Chicago HI's would know more about that. RH

Originally Posted by Ted Menelly

A quote from your site

"A few days later, a forensic investigator made a cut in the wall and revealed that the leaks at the flashing and windows had led to extensive decay of the wall sheathing behind the brick."

Wow. You use terms like forensic investigator to your clients and potential clients.

Good luck to you. I guess I will start using big words. I usually say that upon further investigation from a contractor (insert type) there was further damage from water penetration.

No digs intended so please don't think I am down on you. I am just more of the down to earth type home inspector that does not blow or hype things up and am always amazed at how some folks are so into the seriousness of home inspection like it is brain surgery. I get all my work for the direct and to the point speak, both verbally and on my reports. I think if I used terms such as forensic investigator I would lose my long following.

I don't use technical terms in my reports, at least not without definitions, but I also don't talk down to people. However, the use of the term forensic investigator was in my website, not in a report, and was the correct terminology for the person who did the followup. What would you suggest I call someone who does such a specialized service? Do you call your Cardiologist a heart doctor? I'm not sure being folksy is good professional practice.

I'm glad you have succeeded with your methods. Mine work well for me. Best wishes.

Originally Posted by Roger Hankey

>> I doubt that this is the case. I do not believe FRT plywood was used in many single family homes in Chicago, but Chicago HI's would know more about that. RH

Many, if not most of Chicago's single family homes, especially bungalows are and were built so close together that there isn't even five feet between roof overhangs. In some cases it might be impossible to get a body between a home and an adjoining structure - some have NO space between walls built upon/up to the lotline. However, I do NOT recall the Original Poster having indicated this was a single family home.

Much FRT has been found in the area, there was a time when insurers actually encoraged its use. BTW a LOT of unpermitted repair/remodeling/construction work still goes on in Chicago today - ward by ward. Photographed delamination and chemical charing discoloration and transfer of the salts/acids and charing to the trusses appears could be possible classic FRT deterioration.

Here's a link to an older ASHI Technical Journal article on the subject of FRT (its a PDF file link): http://www.homeinspector.org/resourc...RT-Plywood.pdf

Actually I would think it to be fungus damage.. looks like a newer home by the looks of the truss gussets and plywood clips being so clean, very steep pitch roof at that area. if you look real close at the pics w/ magnification you can see what appear to be white strands, typical of White Rot, the brown is typical of Brown Rot, the staining on the truss members appear to be mold. This is very typical of fungus damage and we see it here alot. Advise professional evaluation by qulified contractor both in area of mold and attic ventilation, may need a power vent w/ humidistat for winter issues.. just my take on th pics..