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CostHelper > Home and Garden  > Flooring, Painting & Remodeling > Repairing Floor Joists

Repairing Floor Joists Cost

How Much Does Repairing Floor Joists Cost?

average costMedium: Repair with Sistering $1,000-$3,000 per roomhigh costSupporting the House with Jacks: $10,000-$30,000

In a typical home, the surface flooring (such as wood, carpet or vinyl) rests on a subfloor, which rests on joists[1] -- a series of closely spaced parallel beams that support the floor or ceiling loads. Joists are usually supported by a sill (a long horizontal timber that's the lowest part of the framework and rests on the foundation) or a girder (a large beam that's the main support of the building). When replacing rotted floor joists it's important to be sure the girder and sill are still intact.

Typical costs:

  • If only a few joists are rotted primarily at the bottom, they can be repaired using a process known as "sistering" -- after the rot is cleaned away and the timber treated to prevent more problems, a new joist is laid beside the old one and fastened to it. Total costs will depend on the extent of the damage and the ease of access to the joists (through a basement or crawlspace), but in general sistering averages $100-$300 or more per joist, and could run $1,000-$3,000 or more to repair a tilted, wavy or bouncy floor under an average room.
  • If the floor joists are extensively damaged, it will be necessary to support the house with jacks while the joists are removed and replaced. In many cases, the sill may also be rotted and need replacing. Costs can run $10,000-$30,000 or more for a typical home, depending on its size, the extent of the extent of the damage and the ease of access to install jacks and replace the timbers. If the damage is limited to just one section of floor joists, the project could run $5,000-$10,000.
Related articles: Foundation Repair, Hardwood Floors, Tile Flooring, Vinyl Flooring, Refinishing a Hardwood Floor

What should be included:
  • Joists carry the weight of walls, furniture, people, appliances and anything else placed on the flooring they support. Usually wooden floor joists are 2"x8", 2"x10" or 2"x12" timbers -- their size depends on their length, the amount of "load" they're designed to carry and the building codes in effect when the house was constructed. The Family Handyman explains how joists work[2] .
  • If there is sufficient access through a basement or crawlspace, floor joists can be repaired or replaced without significant impact on the rest of the house. However, if there is limited access, all furniture and appliances must be removed from the affected area and the flooring and subfloor torn out. The Family Handyman explains how to "sister" damaged joists[3] and describes using a jack to raise a slightly sagging floor[4] .
Additional costs:
  • Floor joists can be damaged by boring insects such as termites or extended exposure to water. Before you replace damaged floor joists, you must exterminate the insects or improve the drainage and ventilation so the problem won't reoccur. Costs will vary widely depending on the extent and nature of the original problem.
  • Typically floor joists are repaired or replaced working from below, in a basement or crawl space. But if there's limited access to the joists, it may be necessary to work from above, removing the flooring and subflooring to repair or replace any damaged floor joists. Costs will depend on the extent of the damage and the type of replacement subflooring and flooring chosen.
  • Skilled do-it-yourselfers can sister floor joists with $200-$500 worth of materials.
Shopping for repairing floor joists:
  • provides tips for hiring a contractor[5] .
  • Get several estimates, making clear what is (and isn't) included in each quote. Request and check references; ask about the contractor's length and type of experience; and be sure they're properly bonded, insured and licensed in your state.
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What People Are Paying - Recent Comments
Floor joist in living room 13 by 13 Sheridan IL got a estimate for work
Amount: $14,796.00
Posted by: Margaret cimba in Sheridan, IL.Posted: October 8th, 2019 02:10PM
Contractor: Fountain repairExtent of Damage: Sister joists if needed n replace sill
Got a price for 14,796.00 to take up enough floor to repair joist by sister them or replace if needed. Room is 13x 13 maybe a ft smaller. Replace sill plate in this room only and replace ripped up floor they take up. They want to put 2 by 6 joists in crawl space for floor, with no center support for joist. Is that ok no center support n is price good.? But if they dont need to replace sill i asked what price he said same but he cant see them since floor has to come up to look at them.
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Termite Damaged floor joists, sil plates, sub floor replacement.
Amount: $7,000.00
Posted by: Clutch Cargo in Cherry Hill, NJ.Posted: June 9th, 2019 06:06AM
Contractor: Extent of Damage: 8 new joists, sub floor, sil plates.
I had very significant termite damage to the basement of a home I purchased last year. Thankfully it was discovered prior to closing and I negotiated a payout to do the repairs as we still really loved the house and got a great deal overall. Nonetheless, still a scary proposition when buying with this much termite damage.
8 joists needed to be removed and replaced
Over 40 feet of sil plates, rim plates.
250 square feet of sub flooring had to be removed and replaced. Then I had a flooring guy come in and lay new flooring where the damage portion was removed. This was all in a walk in basement so the crew had PLENTY of room to work, cut the pressure treated wood, put up ladders, etc. We also replaced to headers above walkways between the 2 rooms of the basement.We spent $2000 on removing the electrical and radiator pipes so the carpenters could do the joist work. Overall it was about $10,000 for this job. Expensive but our negotiated amount at closing covered it.
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Looking for Contractor
Amount: $2,000.00
Posted by: Shotgun in New Orleans, LA.Posted: January 18th, 2019 06:01PM
Need outside sill joist repaired/replaced termite damage
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I am a girl
Amount: $250.00
Posted by: 4430 19th St in MERIDIAN, MS.Posted: December 6th, 2018 06:12AM
Contractor: MeExtent of Damage: 6 joists rotten
I am a 47 year old lady who is new to the construction world but love every minute of it. I recently installed 6 2x10x12 floor joist alone with cinder block as my extra set of hands and every joist level and ready to go. I would do this as a living and just got my first job doing it in a basement 11 ft. In the air. Bought some scaffolding and could do that because it pays really well. I will make $2200 on this job clearing away rotten and installing 4 scab ins. I love it!!!
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Replaced 17 floor joists
Amount: $6,000.00
Posted by: RayV. in Columbus, OH.Posted: September 4th, 2016 10:09AM
Contractor: Gerry (neighbor)Extent of Damage: total dry rot
House we purchased at Sheriff's sale was vacant several years and roof leaked. Damaged all floor joists to the extent we needed to replace all 17. Had basement access and we provided all materials. Just the labor only was $6,000. Done in short sections without jacks. He also constructed 2 concrete pillars for support. We had to tear up the flooring and they cut and laid new plywood in half the house. Don't know if 6K was a fair price, but no contractor responded to our HomeAdvisor inquiry. Would appreciate feedback on price.
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Changeing rotten seals b joist siding and paint
Amount: $1,600.00
Posted by: Aymond81 in Lake charles, LA.Posted: June 22nd, 2016 07:06PM
Contractor: Ryan aymond constructionExtent of Damage: About a150 of seals and a lot of siding
Do think they charged me to much
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DIY floor joists
Amount: $500.00
Posted by: Hoping for a collapse while I'm under there in Martinsville, IN.Posted: February 6th, 2016 04:02PM
Contractor: selfExtent of Damage: extensive; rot and insects
We need 2100 sq ft. of 2x10x16' joists (whole house), new sill plate, and apparently also full encapsulation due to a high water table and flat terrain. We couldn't afford the $23,000 price quoted to us, so opted to do the repairs myself. Extremely slow, extremely heavy and difficult, and still FAR from complete. Each joist is a multi-hour event with two jacks, cribbing, and a piece of lumber that weighs close to 80 lbs while seated on the ground. I don't know that I will ever be able to complete this. Bite the bullet, take a second job, finance the project, and have it done by a pro.
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Floor Joist, Shower Stall Reno and Floor Repairs, Honolulu, HI.
Amount: $6,500.00
Posted by: Dave R. Honolulu in Honolulu, HI.Posted: August 15th, 2013 11:08AM
Contractor: CRU KUSTOM WORKZExtent of Damage: Bad wood rot under Shower Stall & Toilet
Cal with CRU KUSTOM WORKZ came out to our Honolulu rental property and submitted a bid to repair our shower stall floor. This is an old 1930's home and we knew it would be some water damage. After getting several bids from other contractors we decided to go with CRU KUSTOM WORKZ because they were within our budget. We live on the Mainland and have a property management company handle our home, but from what Cal has shown use in his pictures that he sends periodically, I am glad we didn't go with the contractors from our property management company. In the photos of Cal's work this guy knows his stuff and we are secured to know that his work is backed. The repairs turned out great and he guaranteed that the house would fall before the repairs he has made. He is humorous and a very great guy, very professional and upfront. Call him if you need any home repairs on Oahu, he is the preferred Handyman there. Thanks Cal for a job well done.
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