I am a handyman by profession, about fifteen years. I’ve pretty much seen it all, and done a lot of it. I’ve owned and rehabbed a few of my own houses and an 1889 apartment building all with good results. I know what I’m capable of and not to get in over my head.
I also was an insulation salesman to new construction in Southern California for ten years. I am familiar with vapor barriers and the principals of air and moisture infiltration.
I had a new house built a year and a half ago where I now live, in Spokane, Washington. This is a fairly arid climate with a reasonable amount of seasonal rain and snow. Between events the humidity hovers around twenty to thirty percent. In the fall and spring evenings can be near freezing days to nearly eighty degrees.
With that background information, here’s my problem. I’m attaching a picture of a porch overhang above the entry deck at the front of my house (about 6 by 30 feet). On days with the frigid evenings condensation forms within the roof area above the deck and drips through cracks between the ceiling sheeting (OSB) onto the deck. This will occur in the mornings till about noon. Almost a quart of water will drip through. This is on sunny days so it is not a roof leak. It is uninsulated area set off from the rest of the house with a vapor barrier (visqueen applied to interior of the insulation envelope). It is conventionally framed.
I stuck a digital camera up through 3″ holes I drilled for four eave vents I have put in. What seems to be the culprit is a pair of 2X6 or 8’s sistered together which run transverse along the entire roof structure. I believe these timbers are chilled in the evening and then sweat during the day as warm air begins to infiltrate. This occurred before I drilled the four 3″ eave vent holes. As autumn in this part of the county nears, I am afraid my vents may not only not cure the problem but exacerbate it.
Any opinions?
Edited 9/17/2006 5:54 pm by Slot Head
Replies
My first thought is that there are log homes that do not sweat. So I would wonder about the wood itself sweating. I think it is highly unlikely.
There must be moisture present for it to freeze or condense. So something must be done to get rid of the moisture. I would suggest using vents that will relieve the area of moisture. I have had three situations where I did that and it solved the moisture problem.
Is there any venting in the porch roof? What are the rooms behind the porch attic? In other words, is there a bath or kitchen against the porch attic?
"Let's go to Memphis in the meantime, baby" - John Hiatt.
http://grantlogan.net/
Baring an unusual condition like maybe a bath or kitchen exhaust fan dumping moist air into the roof cavity, even before I read your post (I had read the title) I thought ventilation. Essentially, what you have is dead attic space. They make a strip vent specifically for that situation. Here is an example:
http://www.airvent.com/homeowner/products/ridgeVents-specialtyFilter.shtml
The "Flash FilterVent" is the one I'm talking about.
That's what I want! The vent strip that abuts the wall at the roof line. Thanks for the tip.
Another idea but more work is to rip out the ceiling and install a vented vinyl ceiling. I can hear the groans now :-) Thing is there is a vinyl soffit product that looks really good: http://www.certainteed.com/CertainTeed/Homeowner/Homeowner/Siding/Prodindex/Vinyl/CertainTeed/Soffits.htm and http://www.certainteed.com/NR/rdonlyres/354A2CEB-DC1E-4A70-ABAD-DA70B485736E/0/209.pdf and specifically the triple 2" "invisivent" product.
Maybe not to the trained eyes around here, but many people don't know it is not wood. Looks like beadboard. Not only have I used this product on my own house but other people's houses as well. See pic attached. BTW the ceiling trim boards are Azek.
I see your new around here. Welcome! You will find that that there is a great deal of info to be had, but the price is that we here at BT always make little problems expensive to fix :-) Good luck.
Edited 9/17/2006 2:39 pm ET by Matt