A: Sagging floors are more common than you might think. In my opinion, the most common causes are wood-eating insects, wood rot caused by water leaks, undersized beams and soil settlement. There are other possible causes, but in my experience the ones I just mentioned account for much of the misery.
A damaged foundation and damaged floor joist are often the leading cause of uneven and sloping floors in an old house. Foundation damage can come from dump crawlspace, aged or poor design, and craftsmanship, resulting in a foundation too weak to hold up your house's weight, especially when you have a wood floor.
In layman's terms, this means typical 2-by-10 floor joists, spanning 16 feet, can be expected to sag about one-eighth to one-quarter of an inch. Not much; however, as the span increases, so does the amount of deflection. In any case, the floor system can be repaired.
Sagging floors are a sign of serious damage to the joists beneath your home and the structure of your home overall. Left untended, this can lead to injury, property loss, and disaster. Worse, insurance companies often will not pay for such losses or repairs if you ignored the issue once the early signs became visible.
The stem walls, posts and pads, or cripple walls underneath your home may begin to settle unevenly, causing the floor to dip in the areas where there's a lack of support. If you have a post and pad foundation, the easiest form of floor releveling is simply post and pad replacement.
Does home insurance cover foundation movement or sagging floors? Foundation damage caused by shifting or settling earth or sagging floors caused by rotting floor joists are typically not covered by homeowners insurance. If the damage is caused by flooding or an earthquake, you'll typically require separate coverage.
While sagging floors are unsightly, they can be dangerous as well. A sagging floor means that it has lost support, and it may eventually collapse into lower levels of the home. The overall structure of your home could be at risk, therefore making repairs a priority is imperative.
Owners of old homes might learn to experience springy or slanting floors as part of the charm, but they are signs of structural damage. As a home buyer, look at whether the floors pitch at all or take a piece of string to test the floor's deflection.
Excess load
If you have bought a lot of furniture or something more substantial like a piano or maybe you might have added an extra feature on your cabinet, it will add extra weight, which will make your floor to sink.
No subfloor is perfectly level, but any signs of unevenness and high or low spots must be remedied. Please follow these requirements: Subfloor unevenness cannot be greater than 3/16 of an inch over a 10-foot span or 1/8 inch over a 6-foot span. Subfloors must not slope more than ½ inch per 6 feet (25 mm per 1.8 m)
Though floor sloping is a common problem, it isn't purely a cosmetic problem. Floor sloping can indicate that there's a much more severe issue at hand. Sloping floors can signify that there is significant structural damage to a home's foundation, warped floor joists, or water damage requiring foundation repair.
Uneven floors are rarely caused by problems with the floor itself. The cause is usually settling or shifting of the foundation underneath the floors. If the floor beams and joists are made from wood, like the ones above a crawl space, they will usually bend rather than crack.
Houses can sink due to settling or compaction issues, which may occur as the weight of the structure, furnishings and people ultimately exerts pressure outward. This can cause the foundation to bow inward and appear to be sinking in the middle.
What Happens if You Don't Fix Sagging Floors? If you ignore sagging floors, it can lead to consequences such as property damage that your insurance company may not cover. It can also lead to injury when someone trips or falls on uneven floors, or even property loss if the damage is great enough.
When your floor drops, dips, or slopes, it often means you have sagging floor joists. Because the ends of floor joists rest on the sill plate, water damage often spreads from sill plate to floor joist. Another common issue – especially in older homes- is notched joists.
The typical costs for repairing sagging floors start at $1000 and can go up to $10,000, with the average rate being around $300 per square foot.
Safety factor is a measurement with which your floor was designed to support loads without collapsing. Most homes have a safety factor of 40 PSF (pounds per square foot).
Sagging or bouncy floors problems are often caused by a weak floor joist that has sagged under the load of people walking on the floor above. If the issue is caused by just one or two joists, you can probably handle it yourself by attaching a “sister joist” to the original ones.
Sagging floor joist repair often requires professional tools and knowledge, so it's not a recommended DIY job. Homeowners can expect to pay between $1,000 and $5,000 for joist repair to fix a sagging floor and restore a home's structural integrity.
Filling in the existing space with a new plywood subfloor will typically cost about $1.50 per square foot for the materials. The average cost of high-end materials ranges from $2 to $7 per square foot.
Average Cost to Level the Floor in a House
On average, you are looking at about $3 – $5 per square foot. So, for a 100 square foot slab, it would generally cost between $300 and $500.