What Causes Sagging Floors?
The most common reasons are:
1) The soil is too soft.
Your supports under your house and the exterior foundation wall both rest on soil. Soils can soften due to rain water making the soil underneath your foundation muddy and the supports will sink in the mud. Rotting tree roots in the soil left during new construction can also make the soil soft or create voids in the soil underneath your supports.
2) High moisture in the wood
Wood framing is strongest when it is dry. When wood framing exceeds 16% wood moisture content it begins to rot and also becomes pliable. These conditions allow mold and fungus to grow on the lumber which eats the wood and causes wood rot. High moisture comes from humidity evaporation off the soil, the foundation walls, and through vents if it is very humid outside.
3) Supports with small footings
The footing is the most important part of any support. The wider the footprint of the footing, the more weight it can hold. Small footings under 24" wide by 24" length tend to sink and settle over time.
4) Improper supports.
Your supports have to be made of a material that will last decades down the road such as coated steel and concrete. Wood supports will rot over time and are subject to termite and moisture damage.
5) Termite damage
Subterranean termites love high moisture environments and they love high moisture wood. Termites come from the ground and travel through mud tubes on the foundation walls and can eat a lot of lumber in one year causing structural damages.
What damages can sagging floors cause?
Sagging floors manipulates everything above the floor.
1) Cracks in drywall
When floors start sagging at least 1/4" down from it's original position, you are going to start seeing cracks in the drywall typically above door and window frames that appear diagonally. It's also common to see cracks in the ceiling drywall where the wall and ceiling meet. All of this will need to be patched in the future and all the walls will need to be repainted.
2) Cracks in tile
Tile flooring, tile backsplashes, tile showers, and granite kitchen counters will begin to crack in the tile grout lines and the tile itself. Since masonry products have very little flexibility, they are some of the first things that crack along with drywall.
3) Sticking door and windows
Doors and windows are installed originally to be plumb and level as best as possible. Sagging floors causes these door and window frames to be out of level and the doors will begin to stick or rub or just won't shut altogether. Windows out of level can jam up or won't open at all.
4) Creaking floors
Sagging floors causes gaps to occur between wood framing and the nails that hold them together. When you step on these gaps it will cause a creak or pop sound that can be very annoying.
Other common damages are gaps between granite countertops and backsplashes, gaps between walls and ceilings, gaps between floors and baseboards. In severe cases sagging floors will cause manipulation of plumbing lines, roof framing gaps, brick cracks, gaps in wood flooring, humped up floors etc.
What are all my repair options to fix sagging floors?
1) Remedy any high moisture first
If your wood framing has a high moisture content (over 16%) then you have to stop your wood from rotting first. You may need a new vapor barrier, encapsulation, or dehumidification to solve this. There is not much point in trying to support rotten wood or wet wood that is in the rotting process.
2) Wood replacement or floor joist sistering
Sometimes lumber under your home needs to be replaced or sistered (doubled up) to be repaired correctly. Typically floor joists or girders that have vertical cracks in them or have experienced about 1 inch of wood rot on the bottom of them need either sistering or wood replacement.
3) Shim up existing supports
Shimming up existing supports is relatively cost effective but it carries no stabilization warranty as you are still relying on the existing supports that have settled in the first place. Common shim materials used are steel plates, composite shims, and wood shims.
4) Install more block piers
Block piers are a multiple day installation as you have to wait for the drying of mortar and then come back to shim them up. Because of the drying and waiting process, block piers tend to be the most expensive option.
5) Install steel floor supports
Coated steel floor supports also known as steel jack posts are the most popular technique used today to support sagging floors as we do not need to wait for the mortar around block piers to dry. They have an adjustable screw assembly at the top that allows them to be adjusted in the future or to lift floors. Our coated steel floor supports sit on 24" wide by 24" length footings and have a lifetime stabilization warranty that come with them.
