Damp, cold room over dirt crawlspace
I recently moved into a 1920’s cottage, concrete and stone rubble foundation, damp basement under old part. Room was added on 1970’s, access via small opening broken thru concrete wall to dirt floor crawl space. Some years ago,6 mil(?) poly was laid over dirt floor (trench actually), now pell mell mess. Very little headroom, insul bats hanging down here and there. I’m claustrophobic and not so agile anymore, so no way this 68 y.o. can crawl in there. (Plumber had to do it when installing hot air heat vvents years ago,poor soul! room still is chilly)…Ideally, I guess we need new 6 mil poly properly laid down over dirt and up fnd walls, if I can find a willing soul to enter the hole, also install new insul bats + chicken wire to hold in place?…I am considering buying a low temp dehumidifier (Whirlpool website claims it’s 50 pint model AD50USL is the only dehumidifier which goes down to 44 degrees”) and install in down in the crawl space opening as far as I can reach. BTW, wiring is marginal: 60 amps? (4 fuses in box, 15 amp each fuse)..Is this 15 amp enuf for the dehumid unit? I am also worried about humidity effect on my piano and my brand new Dell pc which are in that room.And clothes stored in closet are getting mildewed…Thanks for any advice from you knowledgable folks! Paul
Replies
Sounds like you need insulation, air and moisture prevention, and I don't think plastic sheeting and a dehumidifier are going to cut it. This may be an opportunity to check into urethane contractors. See if you can get someone who sprays the stuff to tell you if pumping your joists under the room full of it might not fix what ails ya.
Take a walk around the outside of this room addition/house and check out the:
A. Gutters and downspouts and their runoff areas.
B. The general lay of the terrain to see if rainwater moves away from the house.
C. Exterior siding, flashings at roof intersections, and window and door trim
flashing details for water catching openings.
What you are looking for is where water may be entering the structure/crawlspace and keeping the room addition saturated. Removing the water souce will be far more efficient than the humidifier.
If your experience level is not up to the inspection, search out a professional builder or inspector to "check out" your home for you. Be ready to pay him for his time and expertise, it could save you lots of $$$ in the end.
Clothes mildewed in an interior closet sound like a water leak into the building.
Just some thoughts..................Iron Helix
paul.. after you do the obvious.. as pointed out above.. if none of them apply.. then it is probably ground water .. at that point .. a good 6 mil poly with sand to weight it down and a low-temp dehumidifier will be the only thing left and should work fine... the cost of electricity and getting rid of the condensate will be your biggest problem
Mike Smith Rhode Island : Design / Build / Repair / Restore
Thanks for the input, you all. Let me add some complicating and limiting factors: 1. Cottage is built into a slope, subject to rain&groundwater runoff from above. Gutters, spouts divert roof rain away ok. 2. I don't own the place, don't have big $ to invest, don't know how long I'll be here, landlord willing to do only minimum. 3. Ideally, proper drainage in needed to divert, but there is ledge at foundation base, so tough to do drain tiles, etc. 4. Urethane sprayed up betw joists sounds good but costly for 12x15 room? Anyone can est cost? Low headroom impede spray? Fire hazard? 5. I've seen TV ads here by a local based outfit who spray concrete-like stuff over dirt crawlspace, claims to eliminate mold, etc. I'll check this out Monday. But wouldn't moisture permeate up thru thin crete?
6. Given all these limitations, my options seem headed to re-poly the dirt and a low temp dehumidifier. Can someone advise whether the 15 amp circuit is enuf to carry the dehumid unit without blowing fuses?? Thanks again for advice.
15 amps works for mineMike Smith Rhode Island : Design / Build / Repair / Restore
I was holding out for putting in a good drain around the outside of the foundation. Until you knocked that into the bin.
: )
Cut foam board to fit between the floor joists. Shove in there, then spray expanding foam around all edges to seal it. This will insulate, and will seal out some of the moisture as well.
Re-poly the ground with sand or pea gravel on top of the poly, and use the dehumidifier. Do not run the poly up to cover the side walls of the crawl space.Political discussion on this forum = The blind insulting the blind
Quittin' Time
Luka, your foam board idea sounds good (assuming you mean rigid polystyrene insulation). My local supply co quoted 4x8 sheets, 1", R 7.2 @ $13; 2" sheet, R 14.2 @ $25. These are foil faced both sides. They said don't use adhesive which would eat the foam...could use long nails into subfloor above, with "roofing tins" to prevent puncturing the foil face, or strapping, to hold in place. Any better ideas out there? Would just shoving the board tight up into the joist space be enuf to hold in place?
Edited 10/30/2002 4:33:51 PM ET by paulz
The foil face costs extra, and you may not need it.
Get the blue or pink stuff that is 2 inches thick. Cut it so that it is a friction fit between the joists. Use "Great Stuff" foam sealant all around the edges. It will glue the foamboard in solid, and seal it as well. Great Stuff is not an adhesive, in the way that they mean adhesive. Use it.Don't bogart the Ghost
Quittin' Time
You CAN use construction adhesive on the foam. You just need to check the labels. In fact some are called "faom and panel" adhesive.
If you cut them right friction will hold them inplace before you foam. But if they are loose use some adhesive to stick them in place first.