The national statistic is 90% of wet basements are due to grading issues around the base of the foundation. In order to get rid of the water in the basement in these cases is to simply put more dirt around the foundation and grade it away. The correct slope for the grade is 1 foot of drop for 1 foot of run – in other words, if you are standing 6 feet away from the foundation you should be six inches lower than the foundation. The good news is dirt is “dirt cheap”, and the work is not difficult. It is also important for the roof gutters and downspouts to be functioning correctly and leading the water away from the foundation.
Unfortunately, many unscrupulous basement waterproofing contractors make a bigger deal of water in the basement so that they can sell a “French Drain” system and make more money. There’s nothing wrong with French drain systems because they do work. But why spend the money ($7,000 to $20,000) on a drain system unless you have exhausted the most economical route (fixing the grading problem by putting more dirt around the foundation). By the way, the best type of dirt for this purpose has a higher clay content then normal so that it deflects the water rather than allowing it to drain through towards the foundation.
If you fixed the grading around the property and water is still coming into the basement, the next thing to do is seal any cracks in the foundation wall. Sealing these cracks should be done with a flexible material such as caulking because there will likely be more movement in the crack in the future. The other approach to fixing cracks is to use an epoxy type glue to solidify the crack and make it so that the crack cannot move in the future.
If you fixed the grading and sealed all the cracks and water is still coming into the basement, a French drain system may be your best alternative. The water proofing contractor will cut a trench around the perimeter of the basement floor and install pipes with holes in them in the trench all sloped towards a sump installed in the basement floor along with a pump. The sump is basically a collection tank where the pipes drain the water below the level of the concrete floor. When the water level gets to a certain point the sump pump turns on and pumps the water up and out of the basement. After the pipes are installed in the trench a new layer of concrete is poured over the pipes, except small crack is left between the wall and the basement floor slab to allow water to drain off of the wall and into the pipe. Water has no choice but to enter the pipe and travel (by simple gravity) to the sump pump where it will be pumped up and out of the basement. These systems do work and can make a wet basement dry. Http://safeharborinspections.com
James Ruppert, President
Building Consultant
631-275-8080
http://www.safeharborinspections.com/