Moisture and Mold between OSB and House Wrap – Whole house
We live in ND in a 17 year old house, we were the first owners. It is a split level with vynal siding. It has all electric forced air heat and central air. The walls were consist of sheetrock, plastic, fiberglass insulation, OSB, wovan house wrap, and then vynal sidiing. The house is finished with exception to to the laundryroom in the basement. I was going to install an air exchanger (wife thought the house smelled like cat when we would go away for the weekend, well, we have a cat) and she wanted it to go away. So I removed some of the insulation from the wall in the laundry room and saw that the OSB was all moldy and falling apart. I thought I better check outside. So I started to remove the siding around the laundry room and it was all wet under the housewrap and the OSB was black and falling apart it was so modly. This mold went all the way up to the top floor. I started to look around the house in other areas and found that it was wet under the house wrap and that the osb was rotten and moldy to the point that I could easly push a utility knife through it. We are having a professional mold house inspector come out and look at it. I guess I am screwed due to this being 17 years after the builder built the house if he did something wrong, but what could cause the whole house to be moldy like this? I assume we will have to remove the siding, remove the wrap, remove the osb, remove the insulation, remediate the mold on the 2x6s and then re-insulate, sheet, and wrap and side again. We to say the least are devistated. I am sure insurance will not cover and it is past 10 years so the builder is off the hook. I guess I want to find out what I can do? Is there a building flaw? Was it somethe we did wrong? We did nothing out of the ordanary in the house, no sauna, or anything like that.
Any help on this issue would be great!
Thanks,
Peter
Replies
Legally you're probably screwed, unless you can somehow hang it on some building material supplier's defective product (which is highly unlikely, even when there *is* a defective product).
Being in North Dakota you have the obvious scenario of moisture passing through the walls from the inside, condensing, and causing this damage. However, normally one would expect a halfway decent job on the interior plastic vapor barrier to prevent this, except in areas (around outlets, near windows, etc) where the sealing was sloppy.
If the damage were just around the laundry/utility room I would suspect that either the dryer vent or a condensing furnace flue has been improperly installed. But it sounds like the damage is more widespread than this.
The two other possibilities I can think of on the inside are improperly-routed heating ducts that vent hot air into the walls and a furnace that for some reason is generating "positive pressure" in the house and forcing air out through seams everywhere.
Any of these could be exacerbated by using poor quality housewrap (and to some degree the vinyl siding), but, despite some protestations you will likely get, housewrap itself did not cause this.
From the outside the obvious candidate for a "guilty party" would be the windows and other penetrations. Vinyl siding is hard to flash properly to begin with, and if the windows were improperly installed and flashed relative to the siding, and if the housewrap was not properly lapped at the window flashing, you could easily get large volumes of rainwater behind the housewrap. (This would, of course, tend to be worse around/below windows, and on the "weather" side of the house.)
One other thing to check, which, I suppose, is a sort of "inside" issue, is the attic. Poke your head up there and see if it seem dry or not. It doesn't take much in terms of ceiling penetrations or problems with ductwork to have large volumes of air entering the attic from the house, and moisture in that air will condense on the roof sheathing and often run down (the inside of) the outside walls.
nuts
So am I right that we are talking about a basic gut out from the outside in and a removal of the windows? If so, I know this is hard to estimate, but are we talking 50K to fix this issue?
I'm just a homeowner (in southern Minnesota), so I can't estimate what the costs might be. But I would guess that $50K is on the low end, depending, of course, on the size of the house and how much of the work you do yourself.
Two thought come to my mind:
The first is that the housewrap is/was no good. Perhaps it's an off-brand that acts like a vapor barrier. If that is the case, the damage is explained.
The second thought is this reminds me of the plight of a good friend in Seattle. She owed a condo in a large building. The housewrap on that structure had been installed upside down. In other words, the laps faced upwards and effectively caught any moisture/rain. The sheathing suffered mightily. It was a very expensive fix for all the owners.
OK another thought... The vinly siding is crap and doesn't breath. That would trap moisture just as well as a layer of poly.
The fix: Well if indeed all the sheathing is compromised, then you're going to have to replace it. That means tearing off the siding and sheathing. That's a substantial bill just for the trash. If you can do the work yourself, and it is hard work but not technically difficult, you can do it over some time and save a lot of money.
Not uncommon
Peter, In Indiana I see this a lot. It has always been the house wrap or it's installation at fault. No, no one will help you. Not the builder, not the insurance. You may have had a chance to claim rain event if it were one side and there was a significant rain last year, but... The woven products 17 years ago were folly. They leaked at every penetration and, if installed properly, that was quite a few penetrations. Then nail siding through it and you have a sieve that won't allow the osb to dry out. There is only one cure and it is expensive. Total replacement. In my area we just completed one and it ran $19 per square foot reusing the siding and windows. There is a new system from Huber called Zip wall. You should have your contractor check it out. it eliminates the need for house wrap and keeps structural integrity. Sorry, hope this helps.
condensation point between your walls
I am building a home in Fairbanks Alaska, which is a similiar climate model as yours. It sounds like you don't have a properly installed vapor barrier, which should be installed between your sheetrock and your studs, with no penetrations. Your recepticles, switches and the like should be sealed with acoustacle sealant to the plastic sheeting (vapor barrier). Anyway, I'd recommend doing a REMOTE wall construction, which can be viewed at the Cold Climate Housing Research Center website. It would also increase your thermal barrier. The guys there are pretty timely at answering any emailed questions you may have. Sorry to hear of your circumstances.
What was the outcome?