How To Replace An Interior Window Sill

Window sills are quite prone to damage from pets, plants, and atmospheric condition over time. Repairing or replacing one-time window sills is an like shooting fish in a barrel abode repair projection that only takes a few hours and basic tools.

Before and after photo of window sill replacement.

Nosotros love our homes, but they aren't impervious. Unsightly cracks, dings, and everyday impairment can build up over time and window sills are quite prone to damage from pets, plants, and weather condition. A interior window sill is the lesser portion of the window, and usually has a lip that overhangs the trim molding.

In today's tutorial, I am showing how to replace interior window sills from some of the most common problems:

Rot
Water Damage
Bubbling MDF or pressboard
Pet damage and deep claw marks

Repairing trim is actually applied, economical, easy to install, and simply takes, at almost, a few hours!

Top down view of a pet damaged wood window sill before repair.

Then, start, we have the crime. There's actually three of these that look this bad. This damage is all from a wonderful pup we rescued. Unfortunately, he had severe separation anxiety, simply it seems to have calmed down subsequently a yr of working with him. So information technology's time to say good day to this eyesore!

Tools and Materials

Hammer or prybar
Utility Knife
Hand Saw or Jig Saw
Nails or Brad Nailer (This is the top rated kit we use)
A board and router or a millwork lath to lucifer the other sills in your dwelling
A product to stop rot (you may or may not need this but we have used this one in the by)
Wood Filler
Putty pocketknife
Level
Trim Caulk

Removing Window Casing and Sill

The showtime footstep is always the near worrisome, right? The window itself isn't actually fastened to the interior sill. The sill should be installed into the framing.

Step 1: Remove any side casing

Casing is trim that is around the outsides of doors and windows. Not all windows have casing, as our was but continued to drywall and caulked to hibernate seams. You volition probable take to remove this considering the casing sits on top of the sill, preventing the sill from moving upward.

The photos below are of me removing door casing, but notwithstanding steps apply.

Step by step instructions for removing casing.

To remove casing, cut the caulk line on both sides that hides the drywall and window framing seal. Elevate a razor knife top to lesser to do this, making certain to get the total caulk line if y'all tin can. Cutting any caulk around the sill besides. (photograph one)

I apply a crowbar to pull out the casing from the drywall. If prying, make sure utilize a brace confronting the wall so you don't dent the drywall. (photo 2) Cleanup the excess caulk and remove nails/staples. (photo three & iv)

Often times the casing can be salvaged and put back on if you lot are careful, only sometimes information technology needs replaced.

Step 2: Pry off the sill.

Apply a prybar or chisel to slowly pry the sill up. A hammer also helps. Keep the sill in one piece and so you can employ it as a model when cutting the new sill. Then gear up it aside for afterwards.

Window frame with sill removed from the wall.

Dealing with Rot

At this stage, the biggest thing to watch for is any rot that may be around the frame. Rot volition need to be removed, or it will continue to spread. If yous do find pocket-size mold or rotted forest, supplant or clean and use a product like this to cease rotting.

Rot needs 2 things to happen: a illness inducing bacteria or fungus and water. Make sure that you are fixing the source of the water that caused the rot.

If you find major rot (structural or the water source can't exist found), here is where I recommend seeking professional assist as the window and framing may need to be replaced.

After solving those issues, if any, here is a great opportunity to fill any gaps if they be to ensure a more than air tight seal. Take window spray foam and spray into the gaps and allow to dry. Cutting abroad the backlog foam with a razor bract prior to installing the new sill.

Step 3: Cut The New Sill

Closeup of the bullnose end of a window sill overlapping the wall.

We fabricated our own hither. A elementary run across the router to create a bullnose edge makes any appropriate board a proper sill. If yous practise non have a router, nearly window sill textile can be found in the millwork section at a home comeback shop like Home Depot. Here is an example similar to ours. You will need to cut it to size still. Marker the board using your template from previous sill and cut.

Step four: Attach new sill

Use nails or brad nails to install the wood board into identify ensuring to boom into the framing beneath. I do non recommend gluing as it isn't needed and will make any futurity repairs more hard.

New window sill with nail holes around the edges.

Step 5: Add Window Trim

If you lot had casing to remove effectually the window here is when you can reattached around the window.

Pace 6: Final Touches

This is both the easiest and longest footstep for professional person results. Depending on your detail state of affairs, you lot may demand to:

Make full and polish all nail holes with wood filler in wood areas.
patch any dings in the drywall.
Caulk around the edges of all the window trim and frame.
Prime and paint as needed to match the existing trim in the house.

In our case, the window trim under the sill had some gouges and dog chewing impairment also. I elected to fill up this particular piece as the border cuts are not easy.

Damaged door casing under a window with wood filler in the chew marks.

Proficient Tips

I have used a lot of wood filler and this is my favorite product. I thinned information technology out with a fleck of water to get in the smaller areas.
For filling this type of woods, I love these sponges because they have edges that I can easily control and get into the ridges.
Endeavor to find real forest products rather than the cardboard-like pressboard that new houses use. Information technology is a much ameliorate product that is easier to piece of work with and is less prone to harm and problems.
If you would similar more than information on caulking, cheque out our footstep-by-step guide to Caulking baseboards.

Finished photo of new window sills and white trim. Dark Gray Curtains blue dining room

LOOKING FOR MORE SIMPLE WAYS TO Amend YOUR Abode?

The Easiest Manner to Make Baseboards look Beautiful Again
Make Basic Cabinets Wait Expensive with Trim
Building A Custom Cupboard
How to Paint Old Kitchen Cabinets

Well, now that's over, the dining room makeover volition wait much more finished. It's difficult to make a room inviting, cozy, and beautiful with eye sores such as these. If y'all want to see our finished dining room makeover, check out our home tour tab with all of our before and after makeovers.

Frequently Asked Questions

How practice yous fix peeling pigment on a window sill?

Scrape off whatever peeling pigment. Use a pigment stripper or sand with 120 grit sandpaper until smooth. Vacuum and wipe all grit off, then paint with two coats of durable paint.

Why exercise window sills rot?

Rot needs ii things to happen: a disease inducing leaner or mucus and water. Although sloped, a windowsill is a horizontal shelf where water can accumulate. The first step to repairing rot is to remove whatever exposure to the source of water.

What stop is best for window sills?

A highly durable pigment or poly topcoat is essential for protecting a windowsill. Inexpensive pigment often becomes pasty and items fix on it can stick. Use a satin or semi-gloss paint that is UV resistant.

How much does information technology cost to supervene upon a window sill?

Whether interior or exterior, materials cost less than $l for wood window sills. If you accept to rent a contractor, wait to pay additional labor charges of $100-250. Both calculations presume in that location isn't more all-encompassing harm to the window or framing, which would increase costs.

Weekend DIY project. A pegboard organizer in the craft room above the desk workspace.

More Trim Tutorials

Kitchen Island with Trim on it but not painted. — Calculation Trim to an Island

Crisp baseboards and molding make a wall paint shine. Repairing and caulking baseboards doesn't have to be scary with these pro tips. — Calculation Trim to an Island

PS I beloved seeing your creations! Be sure to have a photograph and tag#cravingcreative on Instagram! You lot can alsostay in impact with me through post-obit me on Instagram, Pinterest, and Subscribing to the Newsletter!

Two windows with blinds closed and grey curtains on either side.

▢
▢
▢
▢
▢
▢
Hand Saw or Jig Saw

▢ 1 Window Sill Board cut to length
▢ Woods Filler
▢ Nails 2 inch finishing nails or brad nails
▢ Trim Caulk
▢ Pigment
▢ Drywall spackle

Cut the caulk line around both sides of the casing and the window sill itself. Drag a razor knife top to bottom to practice this, making sure to go the full caulk line if you tin can.
Use a crowbar to pull out the casing from the drywall. If prying, brand sure to employ a brace confronting the wall so yous don't dent the drywall.
Use a prybar or chisel to slowly pry the sill upwardly. A hammer also helps. Try to continue the sill in one piece so you lot can use it equally a model when cut the new sill.
Measure the sill surface area and employ the erstwhile sill every bit a template if possible. Cut the new sill to size. Dry fit several times as the walls is probable not be completely direct.
Utilize nails or brad nails to install the wood board into place ensuring that it is nailed into the framing below.
Reattach or replace the side casing and trim that was removed with nails or brad nails.
Complete the finishing of the window. Fill and smooth all nail holes with wood filler and patch walls if necessary. Caulk effectually the edges of all the window trim and frame. Prime and pigment equally needed to match the existing trim in the house.

General Tips

I take used a lot of wood filler and this is my favorite product. I thinned it out with a scrap of h2o to get in the smaller areas.

For filling this type of forest, I love these sponges because they have edges that I tin easily control and become into the ridges.

Try to find real wood products rather than the cardboard-similar pressboard that new houses use. It is a much ameliorate product that is less prone to harm and problems.

If you would like more information on caulking, cheque out our stride-by-footstep guide to Caulking baseboards.