Do you have an exterior rotted wood window sill?  With four seasons, humidity, rain and snow the exterior wood around our home has a lot to withstand. Sometimes, it will rot which means it’s time to replace or repair right away.

Exterior Rotted Wood Window Sill

One of the most common places you will find exterior wood rot is your window sill. Because our homes are exposed to four seasons, temperature changes and humidity, wood rot is common on window sills, especially those that have been neglected.

To avoid replacing your window sill, you can work on regularly maintaining to help prolong its lifespan. Apply a waterproof sealer every year or two, and regularly check for cracks and chips. If you find your window sill is starting to crack or chip, fill them in and repair them before the wood begins to rot.

But, if you’ve waited too long and have found rotten wood, it’s time to repair or replace your window sill. We’re here to show you how.

How to Replace Exterior Rotted Wood Window Sill

Step 1 – Getting Started

These are your first steps before you can remove the window sill. Most likely you will have to use a utility knife to break the caulked seal along the sill.  Next you will remove the old nails. You might need to use a pry bar to get this process started, and then move on to a claw hammer.

Step 2 – Removing the Window Sill

Depending on how rotted your window sill is, it may be an easy or more difficult job. If the wood is especially rotted, it may not remove in one solid piece. If this happens you will need to use a circular saw or oscillating blade to finish.

Step 3 – Install New Window Sill

If your old window sill was rotted, you likely will not want to reuse it. You will need to cut wood for a new window sill and then install it. Be sure you have waterproof construction adhesive and 3 1/2 inch deck screws on hand. You will apply the adhesive to the back of the new window sill and then drill it into place. You can clamp it together by drilling in the deck screws. Use an epoxy wood filler to fill in the screw holes. Once it has hardened, sand it down.

Step 4 – Apply Caulking

Apply outdoor caulking along the new window sill.

Step 5 – Replace the Trim
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Replace the trim around your window sill. Fill in any nail holes and sand them down.

Step 5 – Prime & Paint

Be sure you use exterior wood primer and paint for your trim paint. Apply two coats of primer to the window sill and trim. Allow it to dry.

Once the primer has dried, you can paint the sill and trim and let it dry. You might need to apply two coats.

Replacing your exterior rotted wood window sill is a labour-intensive job. After all, it’s more than just a simple repainting job.  Since you are already investing the time to get the job done, you may want to consider repainting the rest of our window sills and trims to keep things consistent. Or, if you’ve been thinking about your curb appeal and looking for a change, now is a great time to change up your trim colour.  You can give your home an entirely new look with a trim colour update.

For many homeowners, dealing with rotting wood is a job they’d rather hire out. If you do not have the skills or the time to replace your window sill and trim, it’s time to call in the professionals.

We recommend you always select a repair company with proper insurance and experienced employees. This will save hassle if something goes wrong, and it is more likely you will get the job done right the first time when you hire someone with experience.

Replacing exterior rotted wood window sills is an imported part of home maintenance. At Home Painters Toronto, we employ a home repair crew because we do more than just painting. Whether you want to repair your rotted wood, maintain your trim, or replace your wood and trim, give us a call. We’d love to help.