Floor joists in a crawl space are usually supported in one of three ways: adding joists or beams, installing blocking between the joists, or adding support columns under the framing. Which one fits depends on why the joists need support, and an inspection shows that.
These are the three options for how to support floor joists in a crawl space:
- Addition of More Floor Joists
- Installing blocking
- Support Columns for Your Crawl Space
In the following sections, we’ll explain these three options more thoroughly. After that, we’ll explain why floor joists fail and share a few signs you should look out for that indicate this is the case.
Addition of More Floor Joists
A problem with crawl space floor joists can go back to how they were installed. If the house was built with too few joists, or with joists spaced too far apart, the floor above can sag or bounce.
In these cases, the repair is often to add joists, beams or both, or to sister new lumber alongside the existing joists. Added framing helps the floor carry its load and can help keep the floor above level.
Installing Blocking
Blocking is another way to stiffen crawl space joists. It does not look like much, but it helps spread the weight of the floor, and everything on it, to the joists next to each other.
Blocking is a piece of wood fastened between floor joists. It ties the joists it touches together so they share the load.
Support Columns for Your Crawl Space
In most crawl spaces, the joists rest on beams, and the beams rest on piers or columns that carry the weight down to footings in the soil. When a pier or column settles or deteriorates, the beam and the floor above it can sag.
Adding support under the beams, such as adjustable steel crawl space jacks on solid footings, gives the framing new points of support. This is part of our structural repair under the floor.
What Causes a Crawl Space to Fail?
These are common reasons crawl space framing fails:
- Rotting joists: Most crawl space joists are wood, and wood can rot when it stays damp. Rotted joists can sag or bounce.
- Missing framing: Too few floor joists, beams or support columns can leave the floor without enough support. This usually goes back to how the house was built.
- Foundation settlement: A small amount of even settlement is normal. Uneven settlement can cause problems in the crawl space and in the rest of the home.
What Are the Signs You Need Crawl Space Joist Support?
If you notice any of these signs, an inspection can show what the framing needs:
- Deformed floorboards: Any deformation in your floorboards can reveal there is an issue with the joists below it.
- Sloping floors: Damage to your crawl space floor joists can cause your floors to slope in a specific direction rather than being flat.
- Wall cracks: Rot and pest problems can cause problems with your floor joists since these features often consist of wood. It can also result in cracks that form in the walls at any level of your home.
- Sticking windows and doors: Problems with crawl space joists can make doors and windows hard to open and close.
How Can You Help Prevent Crawl Space Damage?
These steps help prevent crawl space damage:
- Control crawl space moisture: Excessive moisture is one of the leading causes of crawl space damage. It can rot wood framing and lead to mold and mildew. Encapsulation helps keep ground moisture out, and a dehumidifier in an encapsulated crawl space, along with interior drainage where water collects, helps keep humidity down.
- Address uneven settlement: When a crawl space foundation has settled unevenly, piers are a common repair. Steel piers reach firmer soil and connect to the foundation to help stabilize it, and in many cases to lift it back toward level.
- Have your crawl space inspected: If you are unsure whether your crawl space needs more support, an inspection shows what is going on and what would help.
Have Your Crawl Space Inspected by a Pro
Repairing crawl space joists is usually a job for a professional, who can find the cause and recommend the repair that fits.
HydroHelp911 serves homeowners across North and South Carolina and specializes in repairing crawl spaces.
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Written by
Cory Parks
Owner & President, HydroHelp911
Cory Parks founded HydroHelp911 and leads its structural and moisture repair work for homeowners across North and South Carolina, from the clay soils of the Piedmont to the saturated, sandy ground along the coast.
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