Buying a house – mid-eighties construction, next to the lake.
Under the house is a vented crawlspace with a sand floor. I’m thinking sand and a high water table (did I mention this place is next to the lake?) will make for a fair amount of moisture under there. In the crawl space there is a pit in one corner with a sump pump.
Everyone in this neighbourhood has crawl spaces, those who don’t have leaks all the time. Some boast that their crawlspaces have poured concrete floors.
I have heard that crawls should be treated like mini basements, and should be heated. I am wondering what I should be doing to ensure that this space stays mould free, and that the house stays strong for a long, long time. Should I be Pouring a floor in it, installing heaters and a dehumidifier? Sounds difficult with only 3 ft of space.
The house is on the shore of Cook’s Bay, just North of Toronto in Canada.
Thanks in advance for any advice
Dagwood
Replies
Is there insulation in the floor joists above?
I'm stoppong by after work tonight. Will be sure to get a picture. I don't remember seeing any insulation under there, but that doesn't make sense for a house from that era.
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If there is no insulation in the floor above I'd just poly the floor, seal the perimeter and heat it. I seem to remember a FHB article not to long ago that covered just this.
You might look here: http://www.buildingscience.com/housesthatwork/cold/default.htm
The "boston" section might be adapted to your use (or at least be informative about what Building Sciences would recommend).
Lucky you.
We've got a (strictly seasonal) place on Lake Huron with a sand-floor crawl-space. There is no moisture problem at all where there is some air space between the sand and the cottage. I've slithered into there on my belly, many a time, and the sand is bone dry.
It is damp only where the soil slopes up to meet the cottage (airspace vanishes and run-off from behind is trapped). And, the concrete mini-basement with the sump pump is always damp to wet.
We went for our visit yesterday. There has been no rain up there in weeks, and all the sand on the crawlspace floor was wet. Like gum up your shoes wet. Not quite mud. The Sump was dry.
The pipes down there were sweating really badly, which is to be expected considering it was 44 degrees out. I'm thinking I'll insulate them right away.
The Foundation walls have been insulated with white rigid board insulation, and one bat of Pink Fibreglass Has been put in around all the exterior walls.
The house is heated with Electric Baseboards, and there is a single heater in the basement.
The pics below show what I saw. I didn't see any mould.
Edit: Pics are huge - will resize and repost later.
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Edited 7/14/2005 9:31 am ET by DagwoodBumstead
Pics ResizedView Image
Insulating the pipes is won't solve the basic problem.The first thing that you need to do is to get a vapor barrier on the "floor" and seal it to the wall to reduce the moisture coming out of the ground.You can have lots of moisture wicking through the soil without having liquid water.
Thanks Bill. I don't know why I hadn't thought of such a simple thing to do.
So my to-do list will be:
Insulate underside of floor
Place vapor barier on underside of floor
Place vapor Barrier on top of sand and seal to exterior foundation walls using Black goopy stuff
Insulate supply Pipes
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Edited 7/14/2005 12:45 pm ET by DagwoodBumstead
I don't see any advantage to insulating the floor or puting in a vapor barrier on the bottom of the floor.But I am not really familar with your area, more with the mix climated conditions.But someplace else to look at is the rim joist.Pull out some of the fg and look at the rim joist.The problem is that the FG will allow moisture to move through it to the rim joist.The the insulation insulates the rim joist from the relatively warm crawlspace air (in the winter) and thus you will get condenation.Insulating the floor will make the crawlspace cooler and thus more likely to get the rim joist condensation.
This is what I was referring to. Treat the crawlspace as conditioned space. I'm still trying to locate the FHB article that sealed off the floor and walls of a crawlspace to achieve just this.
Edit: just looked at your pics and this CS looks very much like the one in FHB I was referring to.
Edited 7/14/2005 1:09 pm ET by ripmeister
If I don't Insulate the floor, Don't I lose heat through it?
I was thinking that in the winter the cold air coming through the vents would make for a very cold floor on the main floor.
What I'm hearing from you guys is make sure there is sill gasket around the outside, Seal with Expanding foam or something. Lay plastic on the floor and be done with it. Should I be removing all the batt Insulation, or just checking for dampness under it?
As a footnote. We have wild temp. differences here between Summer and winter. Today we expect a high of 93 degrees Farenheight, but Between December and February we can expect to get below -30.View Image
If I don't Insulate the floor, Don't I lose heat through it?
That's the "why" of insulating & conditioning the c/s--then it's like the difference between the first & second floors of a structure--no insulation needed there.
By sealing the c/s "to" the ground, the ground, a very good heatsink--becomes the insulation. A foot of undisturbed dirt has a pretty decent R value.Occupational hazard of my occupation not being around (sorry Bubba)
The droopy wires are an interesting touch, but fits in well with the string supporting the sump pump.Occupational hazard of my occupation not being around (sorry Bubba)
Those wires are phone and cable. Easy enough to tack up.
The string on the pump is just there to pull it out. THe pump is sitting on the bottom of the sump.View Image
Found it. Check out FHB #153 pp 94-100 entitled Sealing a Crawlspace. If you don't have a copy just get it here online through the article reprint service.
Thanks Rip. I'll check on it tonight.View Image
Just my luck... The reprints listed on the Back issues page jumps from 152 to 154. Hope I've got that one.View Image
"I was thinking that in the winter the cold air coming through the vents would make for a very cold floor on the main floor."No you close off those vents also."Just my luck... The reprints listed on the Back issues page jumps from 152 to 154. Hope I've got that one"Ah! That is the supper secrete issue 153 that was recalled. There are questions about whether the CIA and/or Rove has anything to do with it. But so far no one from Taunton has been called before the grand jury.Taunton CLAIMS that if you call the 800 number that they will sell it to you, but you probably need to under go a security check first.But the individual article can be purchased for PDF download by going to Archive under the FHB website.JLC has two recent articles that you can buy online. The JLC articles are from some one in NC so it a much warmer, humid climate.The FHB was a builder in CT.http://tinyurl.com/bk5h7http://tinyurl.com/av9bv
I just searched the archive and found the article using the title for the search.
Me too! Looks like I'm in luck!
Thanks guys.View Image
> Sounds difficult with only 3 ft of space.
3 ft. is a gigantic luxury crawl space. Mine tapers down to only 8'' in back. If I had your crawl space, I'd lay poly over the sand, pour a slab, and use it to store ladders and gardening tools.
-- J.S.
Don't fight what's working. Jumping in too soon and spending thousands to seal a crawl space that doesn't seem, going by the feeling of your post, to have any obvious problems is an invitation to waste money and time.
If you move in and over a year or so note excessively high energy bills, great gobs of mould or swamp things hiding under the house you can address those problems at any later day. Take your time. That house has been there for some time. Its existence and relative soundness are testimonial to having its bases covered. There is often a subtle wisdom to houses have adapted to their environment with time.
Too often I see people buy a house and while still wild eyed and sure they can make the place perfect they dive into making things 'right'. They fail to understand that most things that are grossly 'wrong' have likely been taken care of. That pushing to gain the difference between pretty good to perfect often ends badly.
I have seen completely open crawl spaces that are adapted to their site. One row of house beside a lake demonstrates the situation: Those that are completely open suffer little damage when the lake rises. The moving water doesn't undermine their foundation pilings and they dry quickly after the water recedes. Those that people have enclosed suffer more erosion, greater stress when the water is flowing around them and they tend to stay wet far longer than those that are left open. I don't know if the situation your facing is similar. The message being that you need to understand the situation, year round and long term, before making major changes.
Good Point 4Lorn1.
I will likely wait till spring to do anything, but wanted to be sure if I should be jumping on this quick.
Heating and moisture problems aren't my forte.
Thanks for the advice everyone.View Image