Has anyone ever seen this before ?? This roof has the the first layer of plywood sheathing, a layer of shingles, a layer of plywood and the top layer of shingles (in this area 2 layers of shingles is acceptable) I have near seen this in 18 yrs. with 2 layers of plywood, How would you report this, call out a licensed roof to cover myself, but the roof looked OK a far as life is concerned. Thank you for your insight
Pretty much as you described. I might use words like unconventional, unorthodox, or unusual. Then maybe weight and fasting concerns. The load is now double. And how can the second layer of plywood be fastened properly?
6 Likes
Yes I see what you mean
One theory is… the second layer of CDX prevents the new shingles from forming to the old shingles which creates bumps and ridges becomming visible. Owner maybe didn’t want to or couldn’t pay for a complete tear off.
A second theory is similar to the first, only this time the first layer of CDX was failing, and the owner couldn’t afford or refused to pay for a complete tear off. Did you have access to the attic space, and did you observe any damage to the sheathing?
3 Likes
I bet it doesn’t leak 
3 Likes
Maybe, but my question was in regards to why the method of installation.
Many times I’ve stepped on a roof, (once even a new roof as in the roofers were still onsite), and catching myself from my foot going through the surface! (Time above was the roofers failed to sheath a triangle shape near the hip peak)!
Ever since… I do not traverse any roof without first viewing the sheathing on the attic side!!
4 Likes
It would have been very hard for the 2nd cheezy roofers to line up the 2nd layer of plywood to the rafters below. Thus the 2nd layer is likely only going into the first layer.
Any pictures from the attic, looking up?
3 Likes
And there’s your answer as to the WHY!
4 Likes
Any reasons for concern for the potential owner ??
Major concerns.
5 Likes
Yes, the roof won’t last as long as it should.
And it may fly off in chunks in a stiff wind.
This is a definite concern. They need to budget for a full tear off roof in less years than otherwise…
4 Likes
Roof dead load increased. Is the roof dead load/live load total still acceptable?
2 Likes
That extra layer of sheathing weighs more then another layer of shingles and may overload the roof structure especially if it snows where you are. In addition to failed sheathing, your interior attic pics appear to show a suspicious, fungus-like infestation within the attic.
A mold remediation contractor and roofer would be prudent on this one.
1 Like
Too much weight for the structure. Lord help them if they get a heavy snow storm or ice storm.
1 Like
I would definitely recommend that this be evaluated further by a qualified roofer for several reasons. That roof now has more than one layer on top of the original shingles. Also, the drip edge does not appear cover the original roof sheathing which is allowing moisture to wick into the original plywood sheathing. Additionally, the top of the roof is almost an 1” higher than the the original roof, I suspect that the water shoots right over the gutter in a good rain storm.
What the roofer did was essentially cover up, or put a bandaid, on an existing problem. And the new owners will now have to rip off the entire roof and any of the damaged roof sheathing when having to put a new roof on at a later date. That is going to be one expensive job and I’m sure they won’t be happy with the inspector if he didn’t point that out to them.
1 Like
My initial reaction is what does your AHJ allow? Here that is a total strip off of everything down to the rafters and redeck for the next re-shingle.
4 Likes
Ok, I know I’m late to this party, but another problem with this roof is the thickness of the sheathing. It’s too thin for the nails to hold properly. Not good!
1 Like
Sam, 2 layers of sheathing, 3 shingle layers, sheathing, shake layer, sheathing,3 tab shingles All had to be removed. The sales person got heck!!!
1 Like
You guys bring up some great points about the issues with layering roofing materials and plywood. Adding that extra layer of plywood seems like it could cause more problems than it solves, especially with the risk of trapping moisture. It might be a good idea to just bite the bullet and do a full tear-off. Sure, it’s more work, but it could save a lot of hassle (and money) down the road. Thanks for all the insights—really helps put things into perspective!
Joe E. Eells
Castle Impact Windows