Taping to fieldstone foundation?

[quicksandfarmer]

I'm trying to think of the best way to tape to a fieldstone foundation that will stay as long as I want it to, and then come off.

Some background: I have a house built circa 1870 with a fieldstone foundation. Since I bought it the basement has had a moisture problem, and periodically (every few years) the water table rises and it floods.

About a ago I rented a concrete cutting saw and cut a trench around the inside perimeter and installed drains and a sump pump. That was a job! The sump pump runs fairly often and the basement hasn't flooded since then, but I'm not sure if it's just because the water table hasn't risen or if what I did really works.

It is still quite damp down there -- typically 85-90% humidity. The next step would be to seal everything. However, I want to make sure that the drains are sufficient before I do that, because otherwise sealing would trap water behind the wall and make things worse. In the meantime I want to do a temporary sealing using plastic sheeting. I figure that will stay up for at least another year, maybe longer.

So far I haven't been able to get anything to hold sheeting to the walls. I have an idea that I think will work, which is to put a layer of 4" flexible flashing (i.e. Vycor) along the wall above grade, and then tape the plastic to it with Tyvek tape. I'm pretty sure that will hold, Vycor sticks to anything and Tyvek tape sticks to Vycor. The one concern I have is that eventually I'm going to want to take it off, and I worry that the Vycor won't come off my beautiful antique walls.

Any thoughts on alternatives?

Thanks.

 

[SpringHollow]

Can you wrap the first foot or so of plastic around pieces of wood and temporarily screw those to your sill?

Ken

 

[RDrancher]

Sounds like a lot of work to try to tape on plastic. I can't imagine it cutting down on humidity. A few questions if you don't mind.

Where was the water coming from in the first place, from the stone in the walls, up through the floor, or where? Do you know the thickness of the walls? When you cut the concrete around the perimeter did you remove the concrete from against the walls and then repour directly against the stone?

 

[quicksandfarmer]

Sounds like a lot of work to try to tape on plastic. I can't imagine it cutting down on humidity. A few questions if you don't mind.

Where was the water coming from in the first place, from the stone in the walls, up through the floor, or where? Do you know the thickness of the walls? When you cut the concrete around the perimeter did you remove the concrete from against the walls and then repour directly against the stone?

The water was coming in through cracks in the floor. I would go down there with a shop-vac and vacuum it up and I could see it coming in as fast as I could suck it up.

The walls are approximately 24" at the top. I suspect they get wider as they go down.

When I cut the concrete I could only get the saw blade within about 6" of the wall so my trenches are 6" from the walls. I have not repoured concrete yet because I'm not positive that my drains are adequate so the trenches are just filled with gravel.

I have another house of similar construction on the same property, but at higher elevation. In this house the basement was pointed and sealed with some sort of paint. Both are unheated right now. Current outdoor weather is 53F, 71% relative humidity. The "wet" house basement is at 46F, 92% RH. The "dry" house basement is 48F, 66% RH. I think the difference is that one is sealed against dampness in the soil.

 

[SpringHollow]

A huge amount of moisture can come through unsealed basement walls. The construction/heating system of the rest of the house determines whether that is a problem or not. Half of our old house's "basement" was equivalent to a crawl space because the dirt was less than 12" from the floor joists. Covering it and the walls with plastic made a big difference in moisture levels. To see if it is worth it, you can always tape up a small piece and see if you get condensation, how much and how quickly.

Ken

 

[quicksandfarmer]

Can you wrap the first foot or so of plastic around pieces of wood and temporarily screw those to your sill?

Ken

My concern is that humidity will cause rot in the framing, so I'm trying to keep the moisture away from the wood. I worry that if the plastic touches the wood it will create spots where the moisture is trapped. The sills are about 24" above grade, so ideally what I want is for the plastic to end above grade but well below the framing.

 

[Egon]

So,the walls are covered in plastic. Moisture is coming through the walls. Where will it go?


Silicon or some of contractor type adhesives may work to hold the plastic?

 

[quicksandfarmer]

So,the walls are covered in plastic. Moisture is coming through the walls. Where will it go?

If the moisture is just vapor then a vapor barrier will hold it. If there is liquid water behind the wall I need to give it some place to go or the hydrostatic pressure will build and something will give. The point of this exercise is to see if what I did with the drains and sump pump was enough to eliminate liquid water behind the wall, or whether I need to do more.

Silicon or some of contractor type adhesives may work to hold the plastic?

I tried silicon and liquid nails. They stick to the walls but not the poly sheeting. Tapes tend to stick to the sheeting but not the wall. I think I need two separate adhesives.

 

[forgeblast]

what about that aluminum tape, it might do the job.

 

[LazySusanFarms]

If you have mositure coming in from the floor, sounds like the perimeter drain system is not catching all of it and there is too much water underneath due to the overall water table. The current home being renovated on This Old House had the same problem and they put a gravel french drain underneath the floor plus a perimeter drain. The center floor drain moved the majority of the water that the perimeter drain did not catch to another location, away from the home.