I have a customer who wants to frame up walls and hang drywall around the perimeter of her basement to make it appear more finished. It is primarily used for her laundry room, storage and a childs play area occasionally. It is completely underground with no daylight access except for a couple of high windows. It is for all intensive purposes a conditioned space since one half of the basement is already finished and has HVAC and is not really sealed off from the unfinished area. Right now(winter) it feels pretty warm down there and there doesn’t appear to be any moisture issues.
It will have a dropped ceiling and she wants to put down carpet(presumably right on the concrete).
While I like Andy Engel’s approach in the issue of FHB March 2005 I’m wondering if I need to go through all the use of foamboard, air sealing, etc. especially in my more moderate climate than Connecticut where he lives.
I feel like the air will be able to circulate between the walls and ceiling and around the perimeter if I frame 1/2″ off the block so there shouldn’t be any trapped moisure anywhere. I guess my only concern would be if cooler air radiating off the block walls might cause condensation on the back of the slightly warmer drywall.
There is a budget to consider and the cost of the foam and the labor involved ads a bunch of extra cost that I’m not really sure is necessary in this case but I could easily change my mind if y’all can convince me otherwise.
Also, I would not get a permit for something like this.
Edited 1/21/2006 12:02 pm ET by dogfish
Replies
Excuse me for appearing picky...
It is for all intensive purposes a...
Back in the hood, we used to say, "For all intents and purposes,"
As far as the basement issue, someone else knows more.
And to think I have an English degree and still am not sure which is correct.
Ah, the benefits of a higher education are hard to quantify.
What about summertime?
The air will be relatively warm and moist. That moist air will get behind the wall. Not enough to warm the relatively cool foundation walls, but enough for the moist air to condensce.
I am interested in this conversation because our daughter and her husband are planning to try to keep the condensation from the basement floor away from the carpet they will install by putting down squares of plywood which are backed with a membrane... from Home Depot. I asked how the squares are sealed so that the moisture can not get up between the joints and could not get an answer. Does anyone know about this product... or a better one?
Thanks for your help.
I researched that product recently and I wasn't sold on it because you are required to cut vent holes in the floor so air can move under there. In my case the only place for the air to move was into the living space which I certainly wasn't going to do. I thought the whole point was to isolate any moisture from the living space?.? If you could somehow vent to the outside it might be o.k. but then the introduction of outside air under there would probably introduce more moisture depending on the season. I just didn't think it was as great a product as they make it out to be once you read the fine print and apply some common sense. It isn't terribly cheap either.
I went with a similar approach to the one Andy Engel wrote about in that March/2005 FHB article I referenced in my original post. Its fairly easy and completely isolates the slab from the finished floor.
Where are you? If you're in a humid climate, keeping the air from those walls is crucial. If a dry climate, then I'd worry less.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
I'm in Western North Carolina. It can get pretty humid here in the summer but I feel like with the heat/air conditioning on in the rest of the house and no insulation in the floor above there's a lot of conditioned air moving around between the conditioned and unconditioned spaces. The ductwok above the new ceiling most certainly leaks to some extent. Enough so I believe to keep the air above the ceiling and the air behind the wall conditioned enough to avoid warm/cool surfaces from contacting warm/cool air.
Your call, of course. I'd still recommend at least a compromise of 1 in. eps foam on the wall. Wouldn't cost much in time or money, and could make an important difference.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein
"Get off your dead #### and on your dying feet." Mom
If not for current, at least for future reference, check out http://www.buildingscience.com. The typical fiberglass and frame deal is a huge no-no. Just finishing up a basement job where I used XPS and 5/8 DensArmor Plus ( Non-paper faced gypsum )
Relying on leaky AC ducts to sufficiently condition space doesn't seem like such a great idea to me. What if someone down the road tightens up those ducts? 2" extruded foam board costs ~$1.50/sqare foot, including installation, not that much when you consider what mold remediation costs.
I'd urge the client to consider insulating the bare concrete walls. Maybe even give her a copy of the FHB article that you referenced (I've referenced that article in a couple of proposals and have included copies of the article with the proposal).
Up here in Northern New England, they are now saying that the only good thing about not insulating your basement walls is early tulips. And with energy prices going north again, how could anyone argue? Besides the condensation issues, what's the R-value of 8" concrete or block wall, maybe 1?
Thank you for your responses. Y'all are right of course and I will pursue it a little further with the homeowner. It would add about $1800 in cost to the project which will probably kill it. But better to do it right than compromise now and pay for it later.
Maybe they shouldn't finish the whole basement then. I did our basement like on building science, 1" eps, and then 3.5" mineral wool on top of that. I think it's R-19, which is overkill for our climate. Electric baseboards to suppliment the heat in the basement, they wouldn't be used much, if it's insulated, and heat is leaking from the ducts. I'm using electric in our basement as well, to isolate sound from travelling through the ducts.