Messages and Online Forum Q&A

Re: Water seepage through concrete block walls

From: info@buildingadream.com
Category: Foundations and Basements
Date: 05 Apr 2000
Time: 23:28:06
Remote Name: 207.82.209.51

Comments

From your description, I assume you're talking about water seepage into the basement area through the concrete block foundation.

Without seeing your situation first-hand, it's difficult to know the extent of the area(s) impacted by the water seepage. However, here are some general hints and recommendations.

1) Water will always find its way through the path of least resistance. Therefore, several precautions are necessary when building a basement subject to water infiltration.

2) First, the concrete block walls should be filled solid with cement or "grout." If they are hollow or only partially filled, this was a result of improper construction. By filling the walls solid, not only are they more structurally sound, but the solid concrete provides a barrier against water entry.

3) Next, a waterproofing membrane or bituminous coating should be generously applied to the exterior surface of the foundation. This seals the surface from water penetration.

4) Today, a good material to use is Bituthene (made by Grace) or equivalent material. Generally it's a good idea to protect the waterproofing membrane from rocks and backfill by padding it with rigid EPS foam (such as 4x8 foot sheets). The foam not only protects the membrane from rupture, but it also provide additional insulation value -- especially if you live in colder climates, such as Canada.

5) Then, to intercept the water before it has a chance to penetrate the foundation, a perimeter french drain should be laid at the base of the foundation with the perforations facing down (not up!). The drainage ditch can be lined with filter fabric to keep dirt and debris out. Then, the ditch should be backfilled with 3/4" drainage rock or similar material.

6) If your lot doesn't have any slope, your only choice is to drain the water into a sump...and pump it out to the street or well away from the house.

All of this sounds complicated. But when you look at it as a system, it provides several levels of protection against water damage -- starting with prevention...and ending with secondary barriers.

For the size of house you describe, the $30K Canadian amount doesn't sound unreasonable to remedy the situation, particularly if the job is truly done properly -- including the waterproofing membrane, additional protection (such as styrofoam), and a proper drainage system with backfill. You should also be sure that the roof drains or rain gutters are not dumping water alongside the foundation. These generally require a separate closed system to remove the water safely away from the structure.

The main concern is to be sure that there is no severe water damage which could have impacted the integrity of the foundation itself. This would be a much more costly repair.

Let us know what you decide to do.

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