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Leaking Stone Wall Foundation? Stop The Water and Finish The Basement

Stone foundation wall covered with closed cell spray foam insulation

Stone foundation wall covered with closed cell spray foam insulation

Older homes with stone foundations are still prevalent in homes today. Unfortunately, many people are afraid to use their basement because of the excess water infiltration that happens with stone foundations. Moisture comes through the walls, underneath the walls, and it seams as through the foundation is constantly moving. But if you are looking for some extra space, you can, at the very least stop and water issues and strengthen the foundation walls. This will get bring your dream of a finished basement from a dream to a reality.

Installing An Interior Drainage System

All foundations have water that is going to leak at the bottom of the wall unless there is some king of drainage system in place to catch the water. Remove about a 12 inch section of floor all the way around the perimeter of the basement. This is a messy process as you will use a concrete saw to initially cut through the concrete and breaker it up with a sledgehammer.

Once the perimeter concrete is removed, dig down about 12 inches and remove this dirt. Then add 6 inches of 3/4 inch clear wash stone and lay 4 inch drain tile over the stone. Cover the drain tile with stone on the sides, leaving the top of the drain tile exposed. Run the drain til to a sump pit that will collect the water that comes into the basement from underneath the walls. Once you have everything connected, install an interior cap that is L shaped to sit on top of the drain tile as you pour concrete over the area to redo the floor. Have a plumber install the sump pump in the pit.

This drainage system is a messy and labor intensive project, but is not a difficult project to mentally perform. If you want to hire professionals to install this type of system, the rate ranges between $30 per foot to $50 per foot. You can get all of the materials and so this yourself you under $1,500.

Waterproofing the Stone Walls

Now that you have taken care of the water infiltration of the floor, it is time to tackle the walls. First, take a push broom and remove all of the efflorescence off the wall. This is the white stuff that seems to always appear on portions of the surface of the wall that flakes off like snow. This is actual salt from the stone and needs to be removed to seal the wall.

Use a shop vacuum to vacuum up any of the debris and laos to vacuum the wall, removing years of dust and dirt.

Clean out your box sills as well. These are the areas between the floor joists around the perimeter of the building. Pull out any fiberglass insulation and clean out any cobwebs or debris.

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Purchase enough closed cell spray foam kits to insulate the walls of your stone foundation and your box sills with one inch of spray foam insulation. The foam has to be closed cell as closed cell spray foam is 98% water resistant, keeping water from penetrating through it.

Put on your respirator and eye protection, hook up the hoses to the spray foam kit, and install the spray foam gun tip that comes with the kit. Start spray foaming. Start up in the box sills first. Spray the edges to makes sure you properly seal the box sills and then fill in the middle. Keep in mind that the spray foam expands to 100 times its original size so do not over spray. Then work in long strokes down the wall, spraying horizontally for easier spray control. You should be able to cover the walls with one coat of spray foam an inch or close to it.

The spray foam wil lfoarm to the stone walls and fill any voids in between the stone. The spray foam will also allow some minor shifting, but add a significant amount of rigidity to the walls.

Now that the basement is waterproofed, it is you can create a finished basement space that will be water free and well insulated from now on.


jellygator from USA on April 18, 2017:

This strikes me as a wide open invitation to mold problems that will be difficult to treat.

Paul Daniele on October 20, 2010:

I am in the water damage restoration business and live in New England which has a lot of old homes with this type of foundation. I find this concept very interesting

I will pass this idea on to my customers who have problems related with this type of water infiltration.

Paul Daniele

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