What would you look for when buying a house? It’s natural to consider factors like the floor layout, daylighting, storage, quality of finishes, and signs of moisture problems. But how alarmed should you be if you discover potential foundation issues in your dream home?
Foundation defects can be serious. Depending on their cause, type, and severity, they may entail a complete foundation replacement - something you probably wouldn’t knowingly commit yourself to. That said, signs of foundation problems are often obscure, only visible to the trained eye. Further, less severe problems may be solved with an inexpensive fix which shouldn’t put you off from your purchase if everything else about the house is acceptable.
What are the types of foundation problems and their causes?
The most common issue is movement. Foundations must be stable to ensure that the home’s structure remains level; when foundations move, parts of the structure, such as studs, joists, and roof rafters, may become unlevel, lose their load-transferring capacity and sustain grave damage. It can also cause damage to plumbing and other utilities in the house.
Foundations can move in several ways. Settlement is the most common, and generally the least worrisome type of movement. It occurs over time after the building is erected. As the soil beneath slowly compresses under the building’s weight, the foundation follows the soil’s movement and sinks. If the movement happens uniformly, the building will remain level and foundation damage will be unlikely.
Differential settlement, on the other hand, causes one part of the foundation to sink more than the others. When this condition occurs, the entire house starts to lean to one side. The loss of alignment causes cracks in the foundation walls, concrete slabs, and the masonry that clads the exterior. These cracks typically appear stepped in a stair-like fashion, with wider gaps at the top than the bottom. Other indicators of differential settlement include sticking doors and windows, leaning chimneys and stairs, and sunken concrete slabs.
All foundations settle as the soil beneath them deforms. If the building is placed on undisturbed, or compacted soil of adequate bearing capacity, the settlement should be minimal and uniform. Problems typically occur when a foundation is laid on soils that have poor bearing capacity, or those that are unstable. For example, clay is an expansive soil that tends to contract and expand as it absorbs and releases water; this type of soil movement can cause foundations to sink or heave. Loam, on the other hand, makes an excellent base for foundation placement as it doesn’t change its volume when exposed to moisture.
Apart from sinking and heaving, foundations can also experience lateral forces imposed by the surrounding soil. The prevailing reason for these is poor drainage. When rainwater or water escaping from leaky pipes has no way to drain away from a building, it will pool and accumulate, eventually saturating the soil. The resulting hydrostatic pressure may be strong enough to crack foundation walls or cause the foundation to move. Cracks resulting from poor drainage and hydrostatic pressure are typically horizontal; if the house has a basement, the cracks may be accompanied by signs of water penetration.
Should you observe any red flags that point to differential settlement or drainage issues as explained above, your best option is to get an experienced engineer’s structural evaluation before you decide to buy the house or walk away from it. An in-depth, professional evaluation of the defects will establish whether they’re cosmetic or structural, whether the soil conditions are appropriate, and which repairs you’ll need to perform.
What types of repairs may be needed?
If the house you’re thinking about buying has small, cosmetic cracks in the foundation walls, you will have to fix the cracks to ward off water penetration. The repairs will entail injecting epoxy or polyurethane foam into the cracks and may cost you anywhere between $500-$1,000.
If the cracks are larger, and the engineer performing the structural evaluation determines that they point to a structural problem, the repairs may be more substantial. More than likely, the origin of the crack will have to be addressed. If the house is built on expansive or unstable soils that have caused the foundation to sink or heave, you will probably have to level the house. There are several leveling methods, most of which raise the sunken structure; these include mechanical jacking and slabjacking, with the former requiring piers that will support the foundation once it’s raised.
If the foundation defects stem from moisture saturation, the site’s grading and drainage strategy may have to be redesigned. Rainwater will have to be channeled away from the house, off the site, and into a suitable outfall location.
This grading and drainage work will happen in addition to the foundation repairs. The procedure will require the services of a civil engineer and a specialized contractor, and you will have to obtain drawings depicting the existing conditions as well as the proposed work. These will need the stamp and signature of a licensed engineer. Before construction may legally begin, you will have to get permits for the grading and foundation repair.
How we can help
If you’re in love with a home but suspect that it harbors foundation damage, Design Everest can help. Our licensed engineers can examine the defects and determine their underlying causes. Whether the damage is cosmetic or structural, we can propose the most suitable and cost-effective solution. If the defects arise from poor soil conditions or inadequate drainage, our civil engineers can evaluate the site and propose a grading and drainage design that will stop moisture-related problems from recurring. Contact us at (888) 512-3152 or firstname.lastname@example.org to discuss your project and receive a quote today.
*Note: The content published above was made in collaboration with members of Design Everest.
You must have an account to comment on the post. Register with us if you are an AEC professional!