Floor Joist Repair Cost

Last Updated on December 27, 2023
Written by CPA Alec Pow | Content Reviewed by CFA Alexander Popinker

Before arranging a floor or creating a room in an old house under renovation, you need to know if the existing floor can support the future load. Removing the floor helps you start from a more solid base and ensures good sound insulation.

If the floor joist can be renovated or repaired, you can get the job done. On the other hand, if their condition or resistance does not allow this type of intervention, then you can start removing the structure, partially or totally.

How Much Does a Floor Joist Repair Cost?

There are several factors that influence the costs of floor joist repair such as the place where you are living, the number of joists which must be replaced, the contractor you hire, and the complexity of the job. In case you only have to repair some damaged joints, the contractor will use “sistering”, a process through which the affected wood is cleaned away of rot and treated to prevent the appearance of rot in the future. After that, a new joist will be attached and fastened to the rotted one.

You might also like our articles on the cost of vinyl plank flooring, pier and beam foundation, or crawl space encapsulation.

The cost of the sistering method would be anywhere between $160 and $350 per joist, depending on the access to the joints and the damage. In case you need to “sister” every joist, you will need to pay anywhere between $1,400 and $3,700 for an average room.

In case all the joists are greatly damaged, the house may have to be jacked up so all the affected joists can be removed and replaced. In this situation, the costs will be anywhere between $16,000 and $37,000, depending on a large number of factors like the ease of access (crawlspace or basement), the contractor, the extent of the damage, and the size of your home. As every job is different and unique, it is recommended to ask for price offers from multiple local contractors.

In general, the repair of floor joists is pretty simple according to Angie’s List. The contractor will locate the damaged joist during the inspection and will attach a second joist next to it for reinforcement. According to the experts, the costs of this repair will be anywhere between $270 and $340 per joist. Though, if the repair is hampered by electrical wire or plumbing, then the affected area may be repaired using plywood. But the cost for this repair method will be, in general, two times more expensive than the method we mentioned above.

Depending on the size of the surface the contractor has to work with and the working conditions, you should expect to pay anywhere between $10 and $13 per foot, according to a structural engineer.

Which are the additional expenses?

In some situations, floor joists may be broken because of water or pests. In case the water is the culprit for the damage, you may have to call a plumber to evaluate the situation. On the other hand, if the damage is due to pests, you may want to call a pest control specialist to solve this problem as well.

In isolated situations, in case the weight of the floor collapsed because of a heavy object, you may have to call a structural engineer to evaluate and solve the problem.

In case the space is limited; you will need to also replace the subfloor and this will increase the overall costs. The cost of this repair will be affected by factors such as how much subflooring has to be replaced and the extent of the damage. Once the subfloor is installed, you will have to take into consideration the flooring as well.

Your house will not be significantly damaged during the repair if there is access to a crawl space or basement. Though in case the access is limited, the removal of the subfloor will be necessary, which results in higher costs.

Important things to consider

Wooden floor joists differ in size, cross-section, production method, and the type of wood from which they are made. The reliability and strength of the structure depend on the choice of wooden beams. Depending on the distance between the walls and the expected load for the floors, use a floor joist made of solid wood or glued products.

Floor joists are made from softwoods, but oak, acacia, maple, and other trees are also often used. The main condition necessary for the strength of the structure is humidity not higher than 12%-14%.

How can I save money?

Ask for multiple price offers from local contractors, especially if you need to repair a large surface. When choosing a contractor, make sure to check references, reviews, licenses, and insurance.