Ways to Damp Proof a Basement ?
Lots of experienced folks on this board, I’m hoping you’ll be able to point me in the right direction.
We have an old house with a concrete basement (walls and floor). The concrete is structurally sound, no cracks or spalling. It’s pretty damp though. Top of the walls are about 1′ above grade. On a hill, no flood worries.
The dampness is a problem. Given the age of the house (1912) I’m sure there is no waterproofing on the exterior basement walls. The house is too close to the property lines to excavate and install exterior waterproofing as a retrofit.
What are your thoughts on how to damp-proof this basement? I’m thinking of using DriCore for the floor (1″ OSB panels with ABS “feet” on the bottom) and installing a floor drain. I’m pretty unsure about the interior walls though. I’ve thought about lining them with rigid plastic sheets (the orange dimpled stuff that’s used for showers… very expensive), normal clear plastic sheeting, rigid polystyrene boards taped together, or some sort of painted product. With a painted product, I’m a bit worried about the mess of sandblasting or acid washing the basement (panel and furnace are down there).
Thanks in advance everyone, I’m looking forward to your thoughts on this.
Replies
Don't put plastic sheets on the walls -- go to http://www.buildingscience .com and you will find lots of useful information.
You basically want to cover the walls (and floor, if possible) in foam. I recommend using XPS foam instead of EPS foam. This will both insulate the concrete (good for energy usage and preventing condensation on the cold concrete surface) and provide a vapor retarder. The Building Science website will explain why you don't want a vapor barrier.
Also see http://www.ovrx.xom
Billy
Thanks Billy, I really appreciated the Building Science link. Impressive site, I now appreciate the difference between a vapour barrier and a retarder (and why I wouldn't want a barrier!).
Previous owners attempted to solve the problem by painting the interior concrete walls. This (and a hell of a lot of other dumba$$ things they tried) didn't work. I'd need to strip the walls to apply a painted product and I'd like to avoid this mess. Based on this, the XPS looks like a good solution--found a Orvix distributor (their system looks sound) but they're 2 hours away unfortunately.
One question to everyone about using XPS or a vapour retarder... Am I correct in assuming that some sort of floor drain will be needed? I know the retarder is meant to avoid outright condensation, but if condensation happens it will have nowhere to go. We don't have a floor drain down there currently, but I'm not adverse to hammering one in (with a sump). Do you think the floor drain is worth it?
Thanks in advance, I'm learning a heck of a lot from all the responses--very much appreciated.
Condensation would not create enough liquid for a drain. Insulating with XPS will largely eliminate it.
If you think there are or could be water leakage problems that cannot be solved from exterior grading, gutters, and downspout extensions, then before construction it may be worth installing an interior perimter drain with a sump, which would help relieve water pressure on the exterior foundation walls. You need to make that call as it does add to the expense -- but it costs much les to do before the renovation than after. Exterior foundation drainage is the best but it is more $$$.
Billy
If you don't have flooding problems, then why would you install a floor drain and drainage mat?
If all you want to do is keep water from wicking through the concrete walls and floor, I would suggest sealing any obvious cracks with hydraulic cement and then painting all exposed concrete with two coats of latex UGL masonry sealer. It works.
Solar & Super-Insulated Healthy Homes
sealing the inside walls only camos the problem till it returns with a vengence...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
sealing the inside walls only camos the problem till it returns with a vengence...
If it's just dampness from capillary action through the floor and walls, then my suggestion will do the job.
If it's liquid water pooling into the basement, then a different fix might be in order. But the poster didn't indicate this was the problem.Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
look to the exterior side of the wall to do the repairs...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
look to the exterior side of the wall to do the repairs...
Did you even read the original post - said it was impossible to do any exterior work.Riversong HouseWright
Design * * Build * * Renovate * * ConsultSolar & Super-Insulated Healthy Homes
I read it...
pick and shovel time...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
http://www.xypex.com
>>>The house is too close to the property lines to excavate and install exterior waterproofing as a retrofit.
How close is too close? There are machines that will work in pretty tight spots. I agree with those who say that the outside is really the way to treat this.
Scott
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
I agree that hitting the exterior walls first would be the best way to go. I don't think I can get there, though. It's a very skinny house on a very skinny lot, 2' on either side to the property lines. (If the house burnt down, we'd have to rebuild even skinnier---it's grandfathered into the current code requirements.) The soils are gravel with some sand, very little (to no) clay so I'd have to shore any excavation deeper than 2' or so (basement slab is 7' below grade).
Even then, I could only access the side walls. The front and back of the original house have had concrete slab-on-grade extensions added over the years, so I can't get to the front and back basement walls. It looks like I'm hooped from an exterior drainage perspective, guess that's the joy of buying a very, very old house.
We're on a bit of a hill and it doesn't look like this building has ever flooded, so it doesn't look like an interior perimeter drain is needed. From all the responses, it looks like a floor drain (near the washing machine would be nice anyways) with vapour retarder on the walls and floor is the way I'll go.
Thanks to everyone for their insight and advice, I really appreciate it!
Peter - keep it simple and keep in mind that your issue (as you describe it) isn't liquid water but rather dampness:- keep your gutters cleaned out
- make sure leaders run away from the house
- Use Thoroseal and/or UGL latex waterproofer on the inside face
- set up a dehumidifier and condensate pump - run the dehumidifier and pump the condensate to grade on the downhill side
- paint the floor with epoxy paint to help combat rising damp
Jeff
Edited 2/4/2008 9:31 pm ET by Jeff_Clarke