Water penetration into the area along the top of your foundation wall can result in deterioration of the sill plate, floor joists and rim board. Water can penetrate into this area in numerous ways. Typically it finds it’s way in through poor flashing and caulking around doors, windows, and masonry, or directly from the exterior if the grading is too high. Ideally you should have 8″ from the top of the foundation wall to the exterior grading to prevent water penetration from rain and melting snow. Often we will see areas around the foundation which have been built up through years and years of adding mulch not realizing that it has been built up above the top of the foundation wall.
The sill plate is typically a 2×4 or 2×6 which is placed flat along the top of the foundation wall. It is bolted to the top of the wall and the floor joists are nailed into it. The connection of the floor joists to the sill plate, and the sill plate to the top of the foundation wall, can be critical in maintaining lateral stability of the foundation wall. If this connection has been compromised, the foundation wall may become unstable and move inward under the lateral soil pressure.
If only a small area of the sill plate and floor framing have been effected by the deterioration, then repair can easily be handled by a local carpenter contractor. If a significant area has been effected, to the point where part of the home is dropping, then the home will need to be shored and lifted and that’s when we would get involved. In some cases the ends of the floor joists are so deteriorated that they need to be reinforced with another joist, which should run from the foundation wall to the next supporting beam or foundation wall. In cases where that would be very difficult it may be easier to install a new supporting beam parallel to the foundation wall and install new joists from that beam to the foundation wall.