Waterproofing Basement Walls
If you're going to have a basement, you'll have to waterproof basement walls and take several steps to avoid having a swimming pool instead of a rec room. The first is to get the water away from your footings by installing a proper drain system. Then you'll waterproof or dampproof the foundation walls, install a sump pump, and make sure your finish grade carries water away from your foundation.
Basement drain Tile
What is a proper basement drain tile system, you say? Well, like everything else in home building it depends. It depends on your local conditions and codes. We've shown a typical footing drain system on our Footings page where we have a paragraph on Drainage. The grapic is shown below. To be safe, take a look at some construction in your area, talk to the building official in your jurisdiction, and if possible, talk to one or more waterproofing contractors.
The "Basement Drain Tile" shown in the picture above could be any of several different things. The old way, which is shown above, is a ceramic pipe installed so that the joints are "open," that is, they is a space between each section of pipe so that water in ther soil around the footing can drain into the tile and be carried off by gravity (the pipe slopes downhill). In this system, the open joints are covered with a piece of tar paper - the stuff they put on your roof before the shingles are nailed on. This is to keep excess dirt from filtering into the drain tile.
Nowadays, it's more common to see perforated plastic drain pipe. This pipe is usually 4" to 6" in diameter and corregated. It comes in big rolls. You can see it at Home Depot or Lowes. The perforations are available in several configurations: all around, bottom half only, or none at all.
The preferred configuration is bottom half only. With the holes on the bottom only, you'll be letting the ground water in without letting in a lot of dirt. Here's a site on this type of material.
Waterproofing Basement Walls
The next step is to waterproof basement walls be applying some kind of waterproofing material or membrane on the outside walls which will extend from the grade line (the ground line around the building) down to and over the footings.
Concrete and masonry are not moisture proof. If you skip this step, you'll end up with a damp (or worse yet, wet) smelly basement.
The next step is to add a sump pump in your basement. This is a pump which is set in a hole (below the floor level of the basement) into which any accumulating water will flow and be automatically pumped out.
The final step is to keep the water away from your foundation. Make sure your gutters are sound and discharging the rainfall away from the house. In areas with expansive soils, this mean four feet or more. The finish grade must cause water to drain away from the foundation. Finally, if you have expansive soils, avoid foundation planting if possible. Plant roots help hold the moisture near the foundation.
For additional information on house foundations,
see Lesson Fourteen of our online course
Successful Home Contracting.