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Floor Joists

Floor joists are typically made of lumber and support the structure of the building. They are typically arranged parallel and go above the home's beam or grinder. They support your home's floor and the weight of everything above it including walls, furniture and appliances.

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What is a Floor Joist?

What Is a Floor Joist?  

A floor joist is a horizontal structure that’s used in framing open spaces. When combined with the floor framing, joists help to stiffen the subfloor shearing, enabling it to function as a horizontal diaphragm. The beams are usually installed after the crawl space or basement has been built. Once in place, they support the floor above. Joists must be parallel, equidistant, and span between beams or load-bearing walls, which transmit their weight to vertical members.  

Joists are usually installed during home construction. A professional can help you choose the right type and install it properly on the subfloor. Floor joists span support beams or walls and are set up at regular intervals. 

Types of Floor Joists 

Several options are available for supporting the floor. Here are the most common types. 


It’s a type of engineered wood joist. They have a long span, are eco-friendly, and can carry higher loads than solid lumber. On the flip side, these joists aren’t resistant to fires or water. 

Solid Lumber:

Made from wood, solid lumber joists also happen to the most affordable. Their cost depends on board size and wood grade, which are factors that determine their longevity. 

Open-web Floor Trusses:

If you’re looking for joists that offer a range of depth, have longer spans, or greater load capacities, go for this type. Wood trusses have low moisture levels and shrink less. 

Telltale Signs of Failing Floor Joists  

A sagging floor is the biggest telltale sign of damaged joists. Other signs to look out for include:  

Once you notice any of these signs, you need to have the joists repaired immediately.  

How to Fix These Problems  

To keep your floor joists in the best possible shape, you need to keep the humidity levels in your home under control. Otherwise, the joists will begin to rot. Waterproofing your foundation is necessary if you want to avoid these problems. To avoid replacing entire joists, fix broken ones as soon as possible. If your floor joists are no longer able to bear the load on their own, SettleStop Floor Supports can provide the reinforcement they need and prevent sagging floors.  

Damaged floor joists should be repaired as quickly as possible. If you have noticed the common signs of floor joist failure, call the local experts at Groundworks. We provide a free inspection and repair quote. 

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