Waterproofing a Basement is a Daunting Task for Any Homeowner

Every waterproofing job that I have ever been involved with has been completely different. Each one has its own set of unique variables that can make the resolution seem quite complicated.

Occasionally the causes are quite simple to identify and even easier to rectify, but more often than not the causes can be quite complex, and the cures can be even more elusive.

While starting on a new project it is wise to collect as much data as you can about the situation before making any suggestions as to how it can be fixed. Some basements were wet from day one, and others just started to leak last year. There is hidden data in each homeowners memory of the situation, and gleaning from them the real causes of the damp basement may be one of the hardest parts of the job.

First thing you need to do is assess the entire situation from the outside in, looking for issues with drainage like blocked or missing gutters, downspouts and drainage tail pipes.

Look at the inside walls checking for clues as to where the water pools, is it coming down only one wall, does the slab seem wet. Ask questions like is it more prevalent when the air temperature is higher? Does outside humidity seem to add to your problem, and does the entire house have proper ventilation and insulation.

One of the first places that damp humid air can enter a closed space is through the gaps and cracks above the block walls between them and the sill plate. This should be sealed really well to prevent moisture from permeating into the basement. Obviously cracks in the walls and floors should be addressed immediately, and any issues with sump system need to be corrected first.

You can do a test with some squares of tin foil taped to the floors and walls and after 24 hours look to see if there is moisture under the foil or on top of the foil. Worst case it will be present on both sides, but typically it is one or the other.

If the moisture builds up under the foil then you probably have issues with the vapor seal or footer drains around the perimeter of the basement. If this moisture builds on the top side of your test foils then the moisture is a condensation coming from the humid damp air entering the cooler basement rooms.

Fixing moisture coming through the floor or wall can be as simple as clearing the plugged gutters and downspouts to digging up the outside perimeter of the home.

If the air is a problem you can seal up any gaps which are letting humid air into the basement, and then make sure the basement air is circulated well and mix it with air from the rooms above using vents between floors.

To resolve both problems at once you may consider a more complete waterproofing solution such as using waterproof sealer paint on all the walls and floors to keep moisture out. You can then try putting new vapor barrier up on the walls and across the floors such as six mil plastic sheeting using a bead of urethane caulking to isolate the top edge of the sheeting.

Once this sheeting is up you can put perforated plastic pipe under the plastic along the perimeter walls, with these ending into the floor sump. This will allow you to draw air through the area behind the plastic between that and the concrete walls.

Once you have plastic sheeting up you need to put down some sort of flooring that can be covered with carpet or other flooring, and the best material I have seen for this are the rolls of Dri-Core perforated PVC sheeting that has air gaps between the plastic and OSB flooring that you will place over the Dri-Core later.

To enclose this fully you then need to build up a stud wall of some design with foam sheet insulation and mold proof drywall on your studs. This wall can be attached to the joists above, and using liquid nails construction adhesives and a few short screws the base of your new walls can be attached to your new raised deck floor panels.

Once the sump is piped up you need to get a sealed cover that fits the top opening of your sump, with openings for all your pipes, plus a high flow radon pump, which is a special fan used for drawing the moisture from the perforated pipes that were laid along the walls. This pipe needs to exit the basement either through an existing opening or by boring a hole in the cement block.

Remember there are quite a few reputable contractors out there who specialize in doing this kind of repair work, and there are always a few who are not quite as knowledgeable as you would hope, but it is your home so ultimately your decision how to handle the project. Just remember that the cost of doing it wrong can cost you even more later when you have to correct the job again.