Sill Plate Replacement Cost

Sill Plate Replacement Cost

Among all the components that make up your home’s structural framing, the sill plate is arguably the most important. Its main purpose is to essentially anchor your home to the foundation. Whether the sill plate is rotten or you’ve noticed that your floor is sloping toward an outside wall, the sill plate as a whole is faulty. This component is located right on top of your concrete foundation and if compromised, it should be replaced as soon as possible.

The average cost to replace a sill plate is between $95 and $100 per linear foot. More specifically, depending on the size of your home, the extent of the damage, and the ease of access for the repair, sill plate replacement costs could run you between $10,000 to $30,000, or more.

This kind of repair depends greatly upon the extent of the damage, access to floor joists / sill plate from inside or out, size of the house /number of floors, interior / exterior finishes and a bunch of other details that can only be determined by an experienced pro on the site.

The replacement involves jacks being installed to temporarily lift the floor joists to get to the sill plate. Then, the damaged sill plate has to be removed and replaced. As such, it’s easy to understand why the ease of access and extent of damage to the sill plate has a major impact on costs.

In most cases, the sill plate necessitates repair when it is made out of untreated wood and rots from moisture or experiences an infestation of termites. Since the sill plate is responsible for keeping your floor joists level, homeowners will often notice sagging floors when there’s a problem with the sill plate.

However, only a true professional is going to know the difference between a rotten sill plate and a sinking foundation. The latter of which is much more difficult and expensive to repair. Regardless, the entire structure of your home depends on your sill plates and, when they’re damaged, they must be replaced in order to ensure the structural integrity of your house.

With that said, let’s take a deeper look at sill plates as a whole, what the installation and replacement process is like, how much repairs cost, and some additional floor repair pricing. That way, you can appropriately budget for this major home overhaul.

Disaggregation Of The Costs To Replace A Sill Plate

Here we describe all the activities that need to be done to replace a sill plate. This will help us to understand how the costs are disaggregated in each of the activities required.

Contractors usually will take a maximum of two working days to replace the sill plates.

  1. Gather the necessary materials and tools, and excavate to the undisturbed dirt near your house’s foundation. Avoid digging underneath your foundation to prevent cracking the foundation wall.
  2. Since you’ll be positioning four jacks, you need a total of 16 holes under the house. To provide a solid foundation for the lift, the jacks should be placed at least 24 inches from the sill plate on a floor joist.
  3. Place a piece of 24-inch square laminated lumber on the ground, followed by a block, the jack, a piece of 4 by 4 lumber, and a steel plate. The laminated lumber will distribute the load of the jack, while the 4 by 4 piece offers a solid base for the floor joist to rest on and the steel plate spreads the load across a larger area. This same setup will be used for each jack on all four walls.
  4. Once the jacks are positioned, slowly lift the house. Adjust accordingly to keep the house level and ensure that each jack is bearing the same weight. Take your time lifting the house about 8 to 10 inches above the foundation.
  5. Remove the old, rotten, or damaged sill plate and replace it with a new one. You’ll want to use two solid pieces of lumber put together to run the entire length of the foundation wall. In most cases, two 22-foot-long pieces of 8-inch lumber, connected via a 24-inch lap joint and lag screws, is the best option.
  6. Cut the sill plate to length and fasten it between the house and the foundation wall.
  7. Finally, once the sill plate is secured, slowly and carefully lower the house back into position. Finish off by replacing any siding that was removed and remove the jacks.

Disagreggation Of Dill Replacement Costs: Materials Used

Almost all sill plates are made of pressure-treated wood. Pressure treatment protects the wood from moisture due to contact (or close proximity) to masonry foundation materials or from outdoor exposure. The wood treatment also includes insect repellants to protect the wood from termites and other wood-boring pests. Because pressure-treatment chemicals are corrosive to some metals, fasteners and framing anchors that contact sill plate material must be rated for pressure-treated wood to prevent corrosion.

What is a Sill Plate?

Among the many components a house’s structural framing, the sill plate may be the single most important element. On most homes, the sill plate is the first piece of wood in the entire house, and it essentially anchors the house to the foundation. You can see the sill plate from the inside of your house if you look along the top of the masonry walls in the basement or crawlspace. On the outside, the sill plates are covered by the wall sheathing and siding.

Again, the sill plate is one of the most – if not the most – important element of your house’s structural framing. It is basically a piece of wood lumber, usually a 2 x 6 or bigger, that is positioned flat on top of your masonry foundation wall. These sill plates run along your entire foundation and are what the frame of your first floor is built on top of and anchored to.

So therefore, the sill plate is made with wood lumber—usually 2 x 6 or larger—laid face-down on top of the masonry foundation wall. Together, the sill plates run along the entire foundation. The first-floor frame is built on top of, and anchored into, the sill plates. The floor frame consists of common joists, which act like beams and span across the foundation walls, and band or rim joists that cover the ends of the common joists. The band joists are installed flush with the outside edges of the sill plates. The floor joists are covered with a subflooring made of plywood (or a similar material) to complete the floor frame. The first-floor wall frames are erected on top of the subflooring.

As the first piece of wood in the entire house construction, the sill plate is primarily responsible for anchoring the house to the foundation. It is visible from the inside of your home by looking at the top of your masonry walls in either your basement or crawlspace. When viewed from the outside, you’ll see that the sill plates are covered by both the wall sheathing and the siding of your house.

In most cases, sill plates are made from pressure-treated wood, as the material protects from moisture from contact to the foundation or from outdoor exposure. This wood also naturally repels insects, which shields the sill plates from termites and other wood-boring pests. The chemicals in pressure-treated wood are corrosive to some metals, meaning that, to prevent corrosion, the fasteners and framing anchors that are used to secure the sill plate must be rated for pressure-treated wood.

Lower The Costs With A Good Foundation Inspection

Issues with the sill plate that require replacement are usually caused by moisture penetration from the exterior.

A good exterior foundation inspection can often give some hints, some clear signs that moisture was trapped near or witin the foundation.

In fact, this is one of the bullet points that I have defined in my standard foundation inspection checklist.

But usually, these issues are hidden by the sheetrock and the foundation inspector do not break it down.

However, that is not a good excuse nowadays. There are moisture probes that can be poked into walls to determine if there is a higher than normal level of moisture hidden.

More high tech methods involving differential thermography with infrared cameras, and they can often find hidden moisture.

Furthermore, there are devices such as non-destructive imaging including fiber optic probes and ultrasound, that can also be utilized.

I insist, just what I did when dealing with waterproofing the crawlspace, that you could lower a lot your sill plate replacement costs if youhire a foundation inspection and request the inspector, usually a structural engineer, to use infrared cameras, ultrasound devices to measure humidity, and really find out what is going on in the foundation.

Sill Plate Replacement Cost Comparison

Now we are going to compare the sill plate replacement cost per linear feet, with the costs of other projects in the foundation.

Sill plate replacement cost in case that the sill plate is rotten or damaged. Also these prices include repairs to existing sill plates that can be viable after a reparation and do not need to be replaced.$73 to $107 per linear feet and more in some cases
Add fill dirt/regrade @ foundation$500 & up
Add/regrade swale @ yard to improve drainage$450 – $750 p/side
Add/install metal support pole (3”x8’)$100 – $200 ea.
Add/install steel I-Beam (W10x15)$20 plf & up
Inject cracks w/epoxy$350 & up ea.
Labor to set beam/pole$15 plf & up
Build/rebuild detached garage$30 – $50 psf
Build/repair retaining wall$75 – $200 psf
Brickwork (labor to set, metals, etc)$10 psf & up
Install sump pump / drain tile$1,600 & up
Mudjack concrete slab / walk / etc $600 & up ea.
Stonework (labor to set, metals, etc)$15 psf & up
Remove/replace concrete slab$10 psf & up
Repair/replace concrete block walls$225-$350 plf
Repair/restrain 8’ concrete block wall$400 & up p/beam
Repair/replace rotted or damaged joist$100 – $250 ea.
Underpin corner of building$1,100 – $1,300 ea.
Underpin/replace foundation$500 plf & up
Underpin/align masonry chimney$2,500 – $3,000
Waterproof foundation add drain tile- Interior System- Exterior System $60 – $90 plf$85 – $100 plf
Realign foundation wall$85 – $100 & up plf
Install helical tie-backs$700 – $800 ea.

Sill Plate Installation

During a new home build, heavy-duty steel anchor bolts, known as J-bolts, are set into the wet concrete at the top of the foundation wall. The bend at the base of the J-bolts helps to keep them locked into the foundation after the concrete cures. Whereas, the top of the bolts having threading and extent out several inches from the foundation wall.

Once the foundation has cured, the wood sill plates are placed on top of the foundation walls and secured by drilling a hole through the plate at each bolt location. That way, each sill plate rests flush against the top of the concrete. The sill plates are then anchored to the foundation and threaded onto the J-bolts.

It was very common in older homes for the sill plate to sit right on top of the concrete. In newer constructions, there is typically some type of gasket material between the concrete and the sill to further protect against moisture and rot.

Foundation Inspection And Rotten Sill Plates

Unless your sill plate is visible from your crawlspace or basement, a rotten sill is usually a hidden issue that isn’t noticed until the problem gets worse or you’re working on a different home renovation project. However, there are some telltale signs of a rotten sill plate – such as buckling or cracking of your exterior siding, a noticeable dip in one of your rooms, or your flooring being spongy to walk on.

Related Costs Apart From The Sill Place Replacement

The structural framing in your home is all connected. This means that when one component is at fault, others are usually compromised. When you have a rotten sill plate, you may also have problems with multiple parts of your flooring system as well. With that said, here are some other repairs and replacements that may need to be performed, which will add to the overall cost of your sill plate replacement:

Floor Joist Repairs

When your flooring dips, slopes, or drops, this usually indicates failing joists. Since the joists sit atop the sill plate, water damage will usually spread from the sill plate to the joist. Notched joists are also another common problem, especially in older homes, that involves notches being cut out of the joists to make room for the new pipes and ductwork of an updated HVAC or plumbing system. These notches can weaken the joists and result in them splitting, cracking, or failing.

To repair sagging floor joists, they must be sistered because removing the joists completely will damage the subfloor. To sister a joist, a new board is run parallel and attached to the compromised one, transferring the load. Sistering floor joists usually costs between $11 and $12 a foot.

Rim Joist or Band Board Repairs

Rim joists, also known as band boards or band joists, are the wooden piece that sits atop the sill plate. Its purpose is to protect the ends of the floor joists, while also providing support for the exterior walls of your home. Similar to the sill plate, the rim joists can be directly exposed to the outside elements which increase the odds of them getting damaged by humidity.

Like the floor joists, the best way to repair rim joists is using the sistering method. The cost to sister rim joists, or band boards, is between $38 and $42 a foot.

Center Beam Repairs

Floors sagging towards the center of the home is a common complaint among homeowners. This usually indicates that a center beam has failed. In some cases, there are shims that have become compressed and will need to be replaced. The cost to install or replace shims is about $100 a column.

However, if any of the support columns under the center beam have failed and also need replacing, adjustable steel jacks will be installed. The cost of additional steel jack installation is between $175 and $200. Whereas, if the center beam itself has split, cracked, or failed completely, the best course of action is to replace it with a steel beam. Beam replacement costs between $240 and $260 a foot, depending on the number of additional supports required (if any are needed).

Support Column Repairs

If flooring sags in one specific spot, this may be caused by notched joists or beams. In this case, either sister joists or sections of steel beam can be installed to correct the problem. Additionally, it’s very common for sagging floors in a specific area to be caused by a damaged support column. If a concrete or wood support has failed or weakened, it can be replaced by one (or more) steel jack. The cost to install steel jacks is between $500 and $550.

Sill Plates In Different Types Of Foundations

Modern homes that don’t have crawl spaces or basements usually have a special type of foundation called slab-on-grade. With this design, the first floor of the house is a concrete slab rather than a wood-framed platform. The first-floor walls are built on top of the slab or on short foundation walls surrounding the slab. The bottom plates of these walls are actually the sill plates of the house and are anchored to the foundation with bolts. In this case, it would not be incorrect to refer to the wall’s bottom plate as a sill plate.

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