How Much Does Sill Plate Replacement Cost?

The sill plate replacement cost depends on various factors. It is quite a difficult task that will require a professional installer. Replacing a sill plate could cause additional damage to the surrounding material, including the drywall and baseboards. So, hire a professional to get the task done without having to replace any more damaged parts.

sill plate replacement cost

What is Sill Plate?

The sill plate is the most important structural framing element of the house. It is a wooden beam placed on the foundation wall. These plates run along the whole foundation, and the first floor of the building is built on them. The sill plates are very important since they are the first piece of wood in the whole construction. So, this plate is responsible for anchoring the house to the foundation properly. It’s visible when you look at the top of the walls in the basement from the inside of the house. From the outside, you will see that the sill plates are covered by the wall sheathing and the siding.

The sill plates are made from pressure-treated wood to keep them safe from moisture from the foundation or outdoors. It also repels insects and protects the wood from termites and other pests. The chemicals present in this wood can be corrosive to certain metals. Therefore, the framing anchors and fasteners used to secure the sill plate should be suitable to use with pressure-treated wood.

Sill Plate Installation

The first step is to set heavy-duty steel anchor bolts, known as J-bolts, into the wet concrete top of the foundation wall. After the concrete cures, the bend at the base of the J-bolts locks them into the foundation. The top of the bolts have threads and goes out several inches from the foundation wall as well. Then secure the sill plates placed on the foundation walls by drilling a hole through the plate for each bolt. This keeps each sill plate safe against the top of the concrete. Use washers and bolts to anchor the sill plates to the foundation by threading to the J-bolts.

In older homes, the sill plate normally sits on top of the concrete. But in modern constructions, there is a certain gasket material between the concrete and sill plate for additional protection from moisture.

How to Find a Damaged Sill Plate?

The sill plate might be visible from the crawl space or basement. If not, it may be difficult to notice any issues until the problem worsens. You are more likely to find a damaged sill plate when working on the renovation of a different part of the house. But you can detect a rotten sill plate with some signs such as cracking of the exterior sliding or noticeable dip in a room. This is also the case if your floor starts to sag and incline. It’s better to get a professional to inspect the site as they can differentiate between a rotten sill plate and a sinking foundation

How to Replace a Sill Plate?

Replacing a sill plate is not a difficult task if you know the correct procedure. An inexperienced homeowner can do this alone with a lot of preparation and thorough study. But it might take about two days or so for the task. So, it’s always better to get the help of a professional. But if you still want to give it a try, the following steps will help you to get an overall idea about the task.

  1. Find the necessary tools and materials for the replacement. Excavate the ground near the foundation, but make sure not to dig underneath the foundation, or it could crack the foundation wall.
  2. Positioning 4 jacks need 16 holes underneath with at least 24 inches from the sill plate. 
  3. Place a piece of wood 24 inches on the ground and then a block. Then place the jack, a 4×4 lumber, and a steel plate. The laminated lumber distributes the load of the jack. The 4×4 lumber acts as a solid base for the floor joist. The steel plate spreads the load over a larger area. Use the same setup for every jack on all four walls.
  4. After positioning the jacks, lift the house slowly to 8 – 10 inches above the foundation. Take time and adjust the level to make sure that each jack bears the same weight. 
  5. Remove the damaged sill plate and place a new one. You may have to use two pieces of lumber to cover the whole length of the foundation wall. The best option for most cases is to use two pieces of 8-inch lumber with a length of 22 feet and connect them via a 24-inch lap joint with lag screws.
  6. Cut the sill plate to the required length and fix it between the foundation and the house. Then lower the house safely back to the position. Replace any siding that you took off earlier, and finally, remove the jacks.

How Much Does It Cost to Replace a Sill Plate?

The cost of replacing a sill plate is around $95 – $100 per linear foot. So, you can expect to pay somewhere between $10,000 and $30,000. This may even be more depending on the condition of the sill plate and the size of the site. The accessibility and additional requirements or preparations may also increase the labor cost for the replacement.

What Are the Other Additional Floor Repairs?

The wooden frames of the structure in a building are usually connected. So, there is a higher chance of other areas being infected when the sill plate rots. The following are some of the possible floor damages and how to fix or replace them.

Floor Joist Repairs

Angling or dropping of the floor usually indicates failing joists. Water damage usually spreads from the sill plate to the joist as it sits on the sill plate. Older houses have more issues related to notched joists. In this case, notches are removed from the joists to create space for new ductwork. This is the case when using new pipelines and upgrading the HVAC systems. These notches reduce the strength of the joists and cause them to split and crack.

Repairing sagged floor joists need special attention, or it could damage the subfloor completely. Sister the joist by placing a new board parallel and fixing it to the damaged one. This transfers the load safely without causing any damage. Sistering floor joists usually cost around $11 – $12 per foot.

Rim Joist Repairs

Rim joists are also known as band boards or band joists. These are the wooden pieces that lay on the top of the sill plate t protect the ends of the floor joists. It also provides support for the external walls. Direct exposure to the outside environment causes damage from moisture. The sistering method is the best way to repair rim joists, and this costs between $38 and $42 a foot.

Center Beam Repairs

The center beam failure is usually the case if the floors sag towards the center of the house. It could be compressed shims that need replacement. Installing or replacing a shim costs around $100 per column. But if the support columns have failed, it needs installation of adjustable steel jacks which cost around $175 – $200. If the center beam has failed completely due to cracks or splits, then the only solution is to replace it with a steel beam. Depending on the requirement of additional supports, a beam replacement will cost between $240 and $260 per foot.

Support Column Repairs

Notched joists or beams cause the floor to sag in one specific spot. Sistering the joists or installing sections of steel beams can fix this issue. It may also be due to a damaged support column, which is a common reason for sagging floors. You can replace a failed concrete or wood support with one or more steel jacks. The cost of this steel jack installation is around $500 – $550.

who to hire to replace sill plate

Frequently Asked Questions

How Much Does It Cost to Repair a Rim Joist/ Sill Plate?

The cost to replace sill plate and rim joist will range from $10 to $67 per square foot. A full repair will cost between $1,000 and $10,000. This depends on the condition of the damage and the square footage of the area.

Can You Replace a Section of Sill Plate?

Sill plates installed too close to the ground or exposed to water can rot easily. But most of them can be replaced even as sections. You need common tools and materials for the task. But it’s important to have good knowledge of the work you are about to handle.

What Goes Under Sill Plate?

A layer of foam gasket with a thickness of ¼ inches goes on the concrete slab before placing the sill plates. It acts as a moisture barrier between the two surfaces. The gasket should be compatible with the sill plates. So, look for a gasket with the same width as the sill plate you need to install.


The cost may vary depending on the damage and the extent of replacement. However, it is a huge task that consumes time and labor. Knowing the sill plate replacement cost is as important as finding who to hire to replace sill plate in your home. Find the best contractor in your area with the most experienced technicians. This is the best way to have peace of mind that the replacement is done safely.