If you’re researching “old house foundation types,” you’re in the right place. This article is for anyone looking into buying, currently living, or interested in older homes and their foundations. According to the U.S Census Bureau, a little more than 12% of all American homes were built before 1940, with only 5% built within the past five years. That means, out of the estimated 140 million homes in the U.S., 16 million were built before 1940. If you need to know when your home was built, check your county recorder’s website.
Old House Foundation Types
Most occupied homes in the U.S. were built after 1900, using the same foundations found in modern construction.
Most occupied homes in the U.S. were built after 1900, using the same foundations found in modern construction. The main three are basements, crawl spaces, and slabs. While the types of foundations used were the same as now, the materials and building methods were different.
For example, most foundations built before the 1940s were constructed using materials found at the property’s site. The aggregates mixed into the cement were made from rocks dug up when the footings were excavated. This saved time hauling materials to the construction site but came with many downsides.
Old House Foundation Common Problems
Here are some of the most common problems with older foundations.
Aggregates – One of the largest issues with older foundations is the aggregate used in the cement mix. Since these aggregates came from rocks found on site, workers had to use what they found. These rocks were not properly cleaned and were typically larger than desired. (The best aggregate is smooth, small, and rounded.) These substandard materials can cause the concrete to break or wear down faster than usual.
Portland cement – The concrete used in older foundations is substantially lower in quality than concrete made following current standards. Older concrete usually has a lower percentage of Portland cement than used today.
Sand – The sand used in older concrete mix was usually unclean, combined with other materials like salt and beach sand.
Non-concrete – Old foundations built with unreinforced masonry, such as brick, hollow block, and mortared rocks, or when posts and piers were used as a perimeter foundation, came with various issues. These foundations offered less support and strength, unable to withstand earthquakes or aging.
Most homes built before the 1940s didn’t have good drainage or moisture control. In cities that experience small amounts of rainfall, architects purposely leave gutters out of their design. Older basements and crawl spaces weren’t equipped with drain tile systems, sump pumps, or vapor barriers, leaving foundations exposed to moisture buildup. Gutter downspouts in older homes are placed too close to the foundation, leading to water buildup directly outside the concrete (or stone).
Footings & Soil
Footings built before the 1940s were not poured as deep as modern foundations (12″ below grade). Many are 6 inches or less, providing less support than needed. Because of shallow footings, foundations are more susceptible to movement from expansive soil. During the wet and cold seasons, the soil near your footings can swell, shifting your foundation. Then, during the hot and dry seasons, the soil shrinks, letting your foundation shift back into place. This back-and-forth movement is the leading cause of sloped floors, sticking windows, sticking doors, and drywall cracks.
Foundation bolts secure the sill plate (or sole plate) and wood frame of the house to the concrete foundation.
Foundation bolts secure the sill plate (or sole plate) and wood frame of the house to the concrete foundation. Without them, your home’s structure is at risk of earthquakes and other periods of extreme weather. Foundation bolts were only required in 1949 by the Uniform Building Code and were not uniformly enforced by local governments until 1958. If your home was built before or around this time, check with local county records to make sure it has foundation bolts.
Older homes built before 1960 may have cripple walls that separate your ground floor joists from your concrete foundation. These 2×4 or 2×6 framed walls are usually found in crawl space homes with sloped lots. This construction method saves builders from using more concrete to build up the crawl space walls. If these walls are not properly braced, the entire unit can collapse during periods of stress. Contractors can upgrade these cripple walls by nailing ½” plywood to the frame, giving it shear resistance (shear paneling).
If your concrete foundation was built without adequate steel rebar, cracks could form, leading to movement and increased wear.
Concrete by itself is strong but has no integral strength. If your concrete foundation was built without adequate steel rebar, cracks could form, leading to movement and increased wear. Due to irregular rebar size requirements, older homes built in the early 1900s were typically poured without rebar. It wasn’t until the 1950s when the American Society for Testing and Materials released set standards for rebar construction in the U.S.
Posts & Piers
Older homes with post and pier foundations can experience many problems over time. This usually occurs if posts or piers have been added, adjusted, or replaced after the home’s initial construction. This can occur if,
- The concrete used in the piers is of poor quality.
- The top of the piers are at or below soil level, letting the wooden posts touch the dirt.
- Poorly placed shims are added between the posts and piers to correct settlement.
- Piers are installed below current codes without footings.
- Posts are replaced with substandard materials.
Current building codes for crawl space foundations call for at least 18 inches of clearance between the floor joists and the dirt floor. Without sufficient clearance, inspections are harder to perform, and foundation repair experts have to work in tighter work conditions, which could increase their prices. Insufficient access also decreases necessary air circulation, creating a dense and moisture-filled environment.
Older homes combined with age and any of the issues listed above will show signs of foundation damage. If your home’s foundation was built incorrectly, without standard requirements, or shows signs of external damage, get an inspection as soon as possible. Serious foundation problems can decrease your home’s value, worsen over time, and threaten the structural integrity of your home.
Who Do You Call?
If you live in an older home in Chicagoland, call The Real Seal. Our team of professionals will inspect your basement, slab, crawl space, or post and pier foundation, looking for any deterioration or damage. Once you’ve received your free inspection, our repair experts will provide you with a detailed estimate and report, showing you exactly what we can do. Don’t wait. Call today.