Cost To Replace Floor Joists, Subfloor And Boards


Floor joists and subfloor are two of the most neglected parts of a home. However, when they become damaged or worn out, it can lead to serious structural problems. Floor joists provide the support for your entire house so you want them to be strong and sturdy if possible. Unfortunately, many homeowners neglect this part of their homes because they don’t know what’s going on down there under all that flooring! The first thing you notice is a spongy feeling under foot, and it is hard to work out if it is the top board surface, the subfloor, or the joists.

In this blog post we will go over some dos and don’ts when it comes to replacing floor joists, the subfloor and boards in your home (we’ll also give you some cost estimations).

Overview Of Estimating Cost Of Repair

The most common cause of a sagging floor is damage to the floor joists and posts that support the flooring.

There are a number of factors that impact the cost of flooring replacement. These include: the type of wood, whether or not you want to replace your subfloor with new boards, and what kind of finish you want on it.

Estimate Of Labor Costs

A rough estimate for labor costs is around $2500-$3000 per room (400 square feet). This does not account for materials which can add more to this price depending on the type and quality desired – from cork pads ($200) all the way up to oak hardwood floors ($12000)! Plus there will be additional charges if changes need to made in order to accommodate things like stairs or other fixtures as well as any demolition work required. In addition, installing flooring is a job that requires skilled labor and so you will need to make sure the workers have experience with what they are doing.

Estimate Of Material Costs

A lot of the cost for replacing subfloor, floor joists and boards is going to be determined by what type of flooring you are installing. For example, if you’re just putting in new hardwood floors that don’t require any changes to your current framing then it will likely only cost a few thousand dollars-less depending on the size of area in question. However, if you are also looking at adding another level or changing up the foundation (which may include digging into your existing slab), those costs could go up significantly due to things like excavation work which can run anywhere from $1000-$2500 per linear foot! So, before deciding how much you want to spend on these repairs make sure that this is the work you want to get done.

Cost To Replace Subfloor

A sub floor has one main duty, and that is to support to the main flooring material. When this occurs due to termites, weakening, warping, or softening through moisture, it creates a living situation that is dangerous.

In general, the subfloor runs under all the walls in continuous sheets. There is no easy way to remove it.

So when it comes to cost, it is also important to consider the cost of getting the old subfloor removed. Labor costs will be $25 per hour at the low end and over $30 at the higher end.

The cost varies greatly depending on the type of subfloor you’re installing and whether or not you are replacing floor joists. You should plan to spend anywhere from $400-$625 per 100 sq ft (approx. 10 sq metres) which includes materials, labor, and permits. If you’re going with a wood subfloor then expect to pay about $700 for 700 square feet (100% coverage). The good news is that if it’s just your kitchen in need of replacement for instance, chances are there won’t be any extra framing required because typically kitchens only take up 20-30% of the space so even at full price ($756) it still wouldn’t break the bank! Typically people will replace their floors when they notice specific problems such as spongy joints, too much play in the joists, or a need for new insulation.

Can I put new subfloor over old subfloor?

If the old subfloor is significantly damaged, you will have to remove it. It is also an opportunity to re-secure the new subfloor to the floor joists, and in the process, get rid of squeaks or loose subflooring during the new installation. However, if your old subfloor is not too badly damaged, you can install a new subfloor over the old one.

How do you fix a rotted subfloor underneath?

If there are a few rotted patches of subflooring, but the majority is still sound, it is possible to patch the rotted sections with new replacement sections. You need to ensure that adequate blocking is first put in place between joists underneath so as to properly support the patched section of subfloor.

Cost To Replace Floor Joists

To get the best estimation on the cost of repairing a broken floor joist, you should contact a general contractor or handyman. Your flooring system relies on a floor joist to support the weight of the building and offer stability, so it is important to get it right.

Depending on the joist’s position and whether it is easy — or difficult — to reach it, the repair cost will vary. There could be a defect in a floor joist, a split naturally occurring in the wood or the weight of a heavy object that caused it to break.

Replacing joists costs around $100 to $300 for each new joist.

The cost to replace the joists will depend on how much work you can do yourself and whether or not it is necessary to hire a contractor.

Replacing joists is more complicated than replacing floorboards because they are often hidden behind walls. There may be pipes running through the beams which must also be accounted for during removal and replacement. If there’s no way around cutting into wall studs then that means additional expense too in terms of time spent by carpenters as well as materials such as drywall repair kits, insulation and paint.

It’s also important to know that when replacing joists, the carpenter will need access to the old joist. This means either cutting through a wall or removing some ceiling tiles and opening up an attic space.

Because of all these complexities, one approach that can sometimes be used is to employ the technique of “sistering” on a new joist to the damaged one to provide extra support. Of course, this only works if you can get access to the damaged joist to perform such an operation. If that is not possible, you’re left with the other more comprehensive (and expensive) approach which is to cut out and remove the damaged or rotten joists from above. 

Frequently Asked Questions On Cost Of Repair

How Much Does It Cost To Sister Floor Joists?

It will cost approximatly $100 to $300 per floor joist

How Much Will It Cost To Replace Floor Joists For A 500 Square Foot Room?

Around $6,000 to $10,000 or more, depending on ease of access.

How Much Will It Cost To Replace Floor Joists Where A Jack Is Required?

The starting cost will be around $20,000

Repairing A Floor Joist

Installing a second joist next to the broken one and attaching structural screws and glue to it fixes most cases of damaged joists. According to people who have worked on this type of repair, it usually costs between $250 and $300.

Contractors can use plywood to reinforce an area that is easy to reach but is obstructed by plumbing or electrical wiring. Nevertheless, this could result in the need for pipes to be removed and reattached, increasing labor costs. It is not uncommon for this kind of more labor-intensive repair to cost $500 or more.

Repairing Damaged Floor Boards

One approach to repairing damaged floor boards is to place suportive cross pieces underneath the dmaged side on the joist side of the boards. This is an easy thing to do if getting access to the damaged area is straight forward, and a very difficult thing to do if access is limited due to the height of the joists from the ground.

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