- Insuficient waterproofing (damproofed only) with clay soil backfill
- Clogged, broken, none existent weeping tile
- Tie Holes
- Wall Cracks
Poured Concrete Foundations
Common problems associated with Poured Concrete Foundations.
The most common problems found with poured concrete foundations when it comes to moisture are:
Poor Waterproofing (Damp Proofing)
Damp proofing is a light coat of a tar that is sprayed on. Generally it's a very light coating that offers very little protection from water penetration. The problem is compounded when the backfill material is clay which hold the water. The porous concrete draws the moisture in. If the basement is finished the moisture is trapped behind the walls and insulation which is where the mould will grow.
Air is your Friend
If you cannot afford to waterproof you should keep your concrete foundation walls exposed and have good air circulation.
Cracks in the floor or the space left where the floor meets the wall rarely leak as long as the sump system and weeping tile system are working properly. Sometimes this joint can show signs of moisture in areas in alcoves, bays or far from the sump pit. This joint can be injected with urethane and stall the water enough to allow it to drain. This is assuming the weeping tile is not blocked.
Cracks in the floor should never leak. If water is coming up through floor cracks, the weeping tile or sump pump are likely the culprit.
Tie holes are where the left over metal of the rods that were holding the concrete forms together during foundation construction. Ties are usually round or flat. Round ties can be a problem when used in colder conditions. As the forms are removed, the ends of the tie rods are broken off with a hammer. Because the concrete walls cure significantly slower in the winter months, striking the ties can loosen the bound with the concrete creating a wall of leaking ties.
Repair is simple and can be done by coating the surface of the hole with a two part epoxy or urethane paste or even hydraulic cement.
The most common cause of basement water in homes is from leaking wall cracks. Concrete walls will crack due to the release of water during the curing process. Cracks will commonly be found near breaks in the wall (such as windows and beam pockets) or in the middle of long walls uninterrupted by turns in the wall. These cracks will not automatically leak but often do. Surface repairs with rigid products such as hydraulic cement or epoxy will often fail again within a couple of years. Proper crack repair requires that the cracks be fully filled with either epoxy resin or urethane foam.
Honeycombs are areas in the wall where the Portland cement has not been able to completely cover the aggregate. Some causes are the concrete remaining in the truck too long, concrete was not vibrated at pour or a second pour over a first. Honeycombs can often be repaired with simple patching, though some will require an epoxy or urethane injection if they continue to leak after patching.
Another area where water problems are commonly found is at the point where pipes penetrate the wall. Usually the space around these pipe are filled with Hydraulic cement which begins to cure in minutes so may only be pushed 2 to 3 inches into the wall.
Vibration in the pipe, along with other factors, will often break the seal of the cement. A common ineffective approach is to re apply the cement or to coat the area with a sealant. Coating the surface of the basement interior wall, typically, will not stop leaks. The cost-effective and permanent repair involves drilling through the old patch into the void behind it and injecting non-shrinking urethane foam to completely fill the void.