Can I close up my crawl-space?
First, I live in the temperate Pacific Northwest (Seattle area). My older home has a plastic sheeting covered crawl space with numerous vents. It also has insulated Pex tubing for the baseboard radiator system we installed throughout the house when we moved in. The Pex tubing, despite the insulation, still gives off a fair amount of heat when the heat is on. This year, based on what I’ve been reading, I decided to block the vents during the winter and see if it might make some small difference in the temperature of our uncarpeted floors as well as energy savings.
But my question has to do with the pros and cons of closing off my crawl space permanently? There seems to be some new research that suggests open crawl spaces might not be the best way to control moisture, mold, etc. What do others here think?
Here are some links on the research done recently on crawl spaces:
take a look at this link, seems like colsing it up is the way to go.
Very interesting article. Thanks, Chris. I see that it's a bit more complicated than I presumed. Who, for example, is spray foam insulating the floor framing? A "conditioned" crawl-space is interesting and I wonder how much of that is being done retroactively? Not sure that's an option for me. There is vinyl sheeting on the ground, but none of it's taped to the concrete foundation; it's all very loose and weighted down with bricks and stones. Of course, the foundation walls are not insulated either. So, would blocking off the vents still be better than leaving them open? Probably.Thanks, again, for more on this change in thinking.
I have plastic on the ground and 6" open faced batts on the concrete perimeter.
The 6" batts cover up the vents. There is nothing on the bottom of the floors above the crawl space.
For a minimal cost you could have the 6" batts installed around the crawl space perimeter.
The unfaced batts let moisture through them so condensation shouldn't be a problem.
I think the perimeter walls are pretty cold in the winter and they have a fair amount of surface area. I live in Northern CO so it get fairly cold.
I failed to mention that the floors above the crawl space do have open-faced insulation on them. Sounds like I would I still benefit from batts on the concrete perimeter, although it rarely gets into the twenties here and when it does, only lasts a week at most.
My crawl space is around 3-4' in height so the parimeter walls are around that height.
That is a large surface are that is radiating cold into the space. Along with the open vents it is a major contributor to lowering the temp.
You said your pex tubing is giving off a fair amount of heat. So it is heating that space and it is venting outside.
If you closed off the vents and insulated the foundation walls that heat should bring up the temp of your floor a bit.
Personally, I wouldn't do the insulation. They are open faced batts in a cramped space. You could have it done pretty inexpensively. I'd make sure they leave no gaps and that the batts go all the way down to the dirt. Mine turn at the bottom and go out a few inches. That way you know it is in complete contact.
Edited 11/24/2008 10:27 am ET by popawheelie
Thanks, popawheelie. I think you're saying I SHOULD insulate the foundation walls (you wrote "I wouldn't do the insulation)? I will consider it, maybe get a bid. It would be a nasty job....even for midgets and leprechauns. :0)
I meant I wouldn't do it myself. I don't like fiberglass insulation and it doesn't like me.
When it is an open space and I can handle it at arms length it is ok.
You'd have to get some prices on it. How much could they charge? It should go fast if they do it alot.
Do better than close it off, dig it out and make a basement!
That's a laugh. You haven't seen my crawl space! I think I might have one foot of clearance between the dirt and the floor joists on one whole end of my house. The better end might give me 2-2.5 feet tops.
Personally, I think you are in good shape. The VB on the ground is nice. I'd consider operable crawlspace vents ... open in summer closed in winter. That has been fairly standard throughout the NW for a long time. I don't think I would agonize over it, though. There may be other areas of your house that are more important.
Thanks for posting clewless. Yes, I just came across these bi-metal vents that open and close at 70 degrees and 40 degrees respectively. The vents that were in there were interior louvered heating vents long ago rusted in the open position.I'm slowing replacing all the single pane windows in the house with double pane. That's made a big difference.
Here in Alaska recently coerced into venting crawspace against my better judgement. Vents are 4" ABS periscoped in the wall cavity. It is all below grade with 6 mil VB over dirt floor and insulated side walls. In summer warm moist air from outside comes into crawl and lo and behold the moisture condenses...had a bit of mold starting until my point was proven and closed off the vents.
pete,Another stake in the heart of crawlspace venting! Thanks for posting. Do you intend to keep them permanently closed off? I just finished blocking off my vents with 2" styrofoam. I don't have insulated side walls (that would be a major pain in the rear), only VB over the dirt floor. I'd like to permanently close them off, if possible. I'll see how the space comes through the winter. I think I can already tell that the floors are warmer this year.
I would like to keep the vents viable...at least in case I ever were to sell some inspector would want the crawlspace vented or no loan for you! Put an inexpensive hygrometer down there to monitor humidity...interesting to track over the course of 4 seasons
we moved into a 150yr farm house 4yrs ago. The main house has a basement . The kitchen had a 18in crawl space off the back of the house.The house is in upstate NY.Our first winter you couldn`t walk on the kitchen floor it was so cold.I demoed the complete room the following summer.Went back and forth on what to do with the new floor.With the help of a friend we chain sawed out the old floor and timbers. We then filled the cavity and sistren with runacrush , tamped it , put down two in. of foam, rerod , wire , and pex tubing. Poured a concrete slab and tiled over that. The most comfortable room in the house now. (was cheaper to do than new wooden floor system with electric hydronic )
Impressive story. Man, that's called creative problem-solving. And you had the technical know-how, not to mention a buddy's help, to make it a reality. Would have enjoyed a slide show of the project.