A house rests on its foundation. A damaged foundation can lead to problems elsewhere in the building such as the deterioration of interior finishes or, worst, a masonry wall that might collapse. Hence, it is important to correct the situation immediately.

Houses sit on foundationsThe problems

Foundations in old houses are usually made of fieldstones with lime-based mortarA mixture of cement, lime, and sand used for laying bricks or masonry. acting as a binder. In more recent constructions, foundations are built with concrete.

The problems that are frequently encountered with foundations are partial subsidence and cracks, as well as water infiltration resulting from these.

The most common problem has to do with the differential settlement of the bearing soil. This settlement is often linked to the soil’s composition. For instance, soil containing clay will lose a lot of its water to the surrounding trees during a drought. Unfortunately, this water is lost for good and a slight subsidence in the soil will take place. If drought episodes are recurrent, then more and more soil subsidence will take place and cracks will start to show up in the foundation, which has to bear a greater portion of the building’s load. But don’t conclude from this that you should cut down the trees on your property! Just water them regularly and all will be fine.

The consequences

These cracks will lead to water infiltration and a settlement in the foundation, a sure sign of which is dislocations in the building’s masonry facing — those famous staircase-shaped cracks that are sometimes seen in brick walls.

Water infiltration can make the wood elements in the house structure rot or can cause mould in the basement or in the crawl space. The effects of a partial subsidence of the foundation wall are more dramatic, especially if this trend persists. In such a case, the integrity of the masonry facing is threatened. If your foundation wall shows a crack topped by the telltale “staircase” in the mortarA mixture of cement, lime, and sand used for laying bricks or masonry. jointsDevice or product for sealing a surface composed of several elements (brickwork)., the situation calls for immediate attention and most likely the intervention of a specialist.

The solutions

The remedy for cracks leading to water infiltration is generally to fill them in with specialized cements, waterproof the wall’s surface and make sure that the ground is graded to allow water to run away from the building.

For ongoing differential settlements, corrective work is more complex. The most current method is to install metal piles to support the foundation wall and its load. A footing is attached to each pile and this assembly is placed underneath the base of the wall or the stones that need to be supported. It is sealed with concrete and, from then on, it becomes the support for the building’s foundation. It is not a matter of raising the house up but rather of stopping its subsiding.

This work becomes mandatory when cracks appear on interior walls, in room corners, and when cracks in the masonry facing worsen with time. These are the “red flags” to watch for.