After putting it off for way too long with quite a few leaks, I had my roof redone in the beggining of Aug. Tore off the old asphalt shingles completely, had the roofer put down a layer of 1/2″ ply over the planks since there were gaps of 1/2″ or greater, 30lb felt and some decent architectural shingles. The roofer came came well recommened.
I was up in the attic recently after some heavy rains (mid Dec) and the framing in the places where there were leaks before seemed wet, above 30% moisture content according to my moisture meter. I had the roofer back, he took the shingles off in that area and the tarpaper showed no sign of water.
The framing dates back to 1892, could it still be holding that level of moisture from before Aug when the leaks were happening? I would have thought it would have dried out by now since there were quite a few hot days since the roof was redone and it is like a kiln up there in the hot weather.
Another thought I had was maybe these areas that were subjected to water from the leaks is more prone to airborne moisture coming up from the house? I’m skeptical that moisture from the living area is condensing on the rafters since it is only in certain places and the soffits are actually open right now so venting shouldn’t be an issue though I didn’t have the ridge vented.
Anyone run across something like this? I don’t want to beat this guy up if it isn’t his fault.
Mike
Replies
Mike
Soffit vents work when there is a way out. Soffit vents on the other side of the house doesn't usually do that.
Where are the areas of higher moisture content? Near bath exhaust fans not properly vented to outside?
Near plumbing vent pipes?
Any penetrations from below not sealed? Houses of that vintage were often balloon framed and more that one I've been in had clear space from basement/crawl right up to attic. Some firestopping, but not always.
And what area of the country-how cold was it b/4 and during when you checked the moisture content?
30%
is the top of the range for a lot of meters. How sure are you that your meter is accurate? I would expect the lumber to be wet to the touch at that MC.
You have changed the way the attic works by adding the plywood and a tight layer of shingles. If you had water leaks before, you had air leaks too, and that may have been helping moisture to leave the attic (moisture coming from inside the house). And, I would expect a leak thru the roofing to be trace-able, in other words you should be able to find where it's coming in. The area of framing that gets wet might not be the same area where the leak is. If I suspected a roof leak I would probably test it with a lawn sprinkler on the roof while I watched from inside the attic. It helps to have two people for that.
Chances are good that at least part of your problem (if not all) is moisture from the interior of the house migrating up into the attic. Most old houses are not well sealed at the attic floor, and you might want to address that regardless of the roof issue, because it will reduce your energy bill.
Well, that roof got sealed up nice and tight... so what are you doing for ventilation now? Is there a ridge vent installed? What about soffit, eave, and gable vents?
Also, did those rafters ever get dried out in the first place. Roofers can blast through a job quick.... maybe this needed more open time.
Venting
No ridge vent I probably should have had that done. Soffits are vented and on one side they are even open since I got caught by winter before replacing the bead board that was there. I'm not sure if the leak areas ever dried out, there were certainly enough hot days after the new roof was put on to have cooked those rafters dry I think.
I'm going to remediate as much of the venting and moisture possibilites if just to cross them off the list but the fact that it is only in certain areas and most of the rest of the framing is dry makes me think it is a leakage issue more that a moisture one.
Is there any roof feature above this wet area that would lead to leaks? A newly-installed asphalt shingle roof basically can't leak in the field -- it doens't know how. Leaks develop either around "features" or when the shingles get old and brittle.
There is something called "Heat drive" (or something similar) that drives moisture deeper into an assembly when it is heated. It's possible that the outside might have appeared dry before, but was still soaked in the middle and is only now slowly equalizing out.
As I live in SoCal, with dry air and wet Canadian wood, I've found out the hard way that you need to let lumber dry gradually and evenly, otherwise it will "check", which means to split open along the grain of the wood.
"the fact that it is only in certain areas and most of the rest of the framing is dry makes me think it is a leakage issue more that a moisture one. "
Wrong!
The wet framing is where it had leaked before and by taking up shingles, he has demonstrated no water is leaking in now, but you have no proper venting to allow this to dry out.
The fact that it got hot means nothing. To dry the wood, it take flow of warm DRY air from soffit to ridge vent. You have instead, a tent so that the heat turns moisture to vapour but gives it no way to vent out and away, so it stays in the attic.
Correct this by adding ridge vents or top hats or you will soon have a mushroom farm eating your framing.
Recommended vent size is one sq foot per 150sf of living space
U say U have soffits open, but what about the ridge? Venting needs to be in AND out both.
Yes it is possible for this moisture to be old or from in house