How To Repair Wooden Window Sill

By Rob Robillard

Wood windowsills have a beating from Mother Nature. Although sloped by design, a windowsill is however basically a horizontal shelf where h2o and snow can accumulate. Once water finds its fashion backside trim or below paint and caulk, the rot procedure begins. Ongoing exposure to this moisture will crusade the windowsill to decay and worsen over time. When caught early on, frequently a pocket-sized epoxy repair is all that is needed. But when discovered late or left unchecked, the rot will penetrate deeper into the windowsill and even the wall framing, requiring much more all-encompassing and more than expensive repair later.

Repair or Supersede

The age-old debate of window replacement or window repair is a tough one to answer, but I'll explicate how I endeavor to guide my client's determination process.

I wait at the repair versus the replacement question as a business approach. What makes the most sense; based on time, budget longevity, and of course hidden costs.

dutch1 — Occasionally woods rot only occurs at the olfactory organ of the window sill.

When dealing with old historic windows, often times repairing is the only choice. Many times these windows are protected by a city or town'south historic district commission specifying that the window details remain unchanged. Often times, replacement requires having a custom and costly window made to match the manner, wait and dimensions of the existing one-time windows.

Other circumstances where repairing may be an selection is on higher-finish homes with big expensive units, bay windows or multiple mulled windows. Many times these windows will have high-end trim, wainscoting or false wall finishes that would add a multitude of extra costs if the window is replaced.

I often opt for window replacement when the price of the window, any interior work relating to the replacement and my replacement labor are equal to or less than the time I'd spend performing a quality repair. I often see this as a realistic option on more modern homes when dealing with stand up-alone window units and simple interior finishes and trim.

Replaceable Sill Nosing

Sometimes a windowsill has rot on the outer nosing simply. Many newer windows actually have removable nosing that can easily exist duplicated and replaced with Western Ruby-red Cedar, Mahogany or PVC. Others are designed as 1 piece and need to exist cut away and patched.

Notch out the rotted areas of the nosing and replace with a matching wood patch. — Notch out the rotted areas of the nosing and supercede with a matching wood patch.

Rot that occurs deep inside of the sill is more difficult to repair.

Before working on the sill, seal off the house interior from dust. — Before working on the sill, seal off the firm interior from grit.

Surround the damaged area with wood strips to serve as a router guide. — Surround the damaged area with wood strips to serve equally a router guide.

Set the depth of the router bit to create a stepped patch to fit into the window sill.

Carefully rout out the old wood. — Carefully rout out the old forest.

Installing a Dutchman Patch

Dutchman patches are known primarily in carpentry, furniture-making and masonry. A Dutchman is a piece of woods or rock that is used to repair a larger slice, shaped so that it fills a void. In our case we cut the void and patched information technology with new wood—a Dutchman patch.

If windowsill rot is confined to only a small surface area, a simple patch and make full is all that is needed. For larger sections of damage, most or all the windowsill may need to be removed and replaced.

When performing a Dutchman repair we like to use Western blood-red cedar or Mahogany for the patch. Both wood species accept inherent insect- and rot-resistant qualities.

Use a Router to Cut Out Rot

We utilise a compact router and guide to cut our Dutchman patch because using anything else does non provide a direct enough line for a tight glue articulation.

A router kicks up a lot of saw-dust, so sealing off the window is a must.

Dust Prevention

Prior to cutting out the rot you will need to take precautions to go on sawdust from inbound the house. We use a product called Tape & Drape, a pre-taped masking film that unfolds to cover and protect diverse surfaces while painting.

Nosotros and then use painter's tape to completely seal off the sides of the plastic, on the inside of the window, and then raise the lower sash to provide access to cutting the sill with a router. This procedure ensures a dust-free house interior.

Shown here is the completed cut-out. — Shown here is the completed cutting-out.

Cut the wood patch on a table saw and seal all edges. — Cut the wood patch on a tabular array saw and seal all edges.

Test-fit the patch and make adjustments as necessary. — Exam-fit the patch and make adjustments as necessary.

Straight Edge to Guide the Router

In order for any tool to cut direct you need to use a guide. We utilize quarter-inch plywood as our router guide, making the guide with a table saw and miter saw.

The patch should fit snugly as into the recess. — The patch should fit snugly equally into the recess.

Secure the patch in the hole and fill gaps with epoxy.

Once we determine where the rot ends and solid wood begins, we utilise that measurement plus the width of our router base to determine what size router guide we need. Small

4-penny finish nails concord the guide in place, and these holes are later filled with epoxy.

Cutting the Dutchman Pigsty

Nosotros set our "straight cutting" router bit to cutting approximately 3/eight inch deep all the way around. We and so added small ane-inch strips to all template sides of the router guide and used the router to make a "stepped dorsum cutting," cutting completely through the window sill. This takes several passes, each time deepening the router cut.

We use this "stepped method" to increase our gluing surface and to provide a shelf for the Dutchman patch to index into and rest on.

Smaller Rot Sections

When presented with smaller rot circumstances, not equally deep, we only rout deep enough to eliminate the rot and cut into solid woods.

Prepare for the Patch

Once the routing is completed nosotros vacuum the entire expanse and inspect the framing sub-sill for damage. If rotting, we may end up removing the window after all. If non, the repair continues.

Finish the job by applying new caulk/sealant and a coat of fresh primer and paint. — Terminate the job past applying new caulk/sealant and a coat of fresh primer and paint.

We apply a chisel to square off the corners of the pigsty after routing. The Dutchman patch is cut on a table and miter saw to ensure square corners.

Cut the Dutchman Patch

We then take measurements and notes to make our solid Dutchman patch on the table saw. The router rode along the sill, sloped 12 to 15 degrees, then we try to lucifer the angle on our patch.

We duplicate this slope with the intent of getting all the sides of the new patch to bear on all the sides of the hole in the sill. This takes fourth dimension to get right and ensure that we have a tight "dry fit" patch. Cut the patch into shape with intersecting rip cuts to create the stepped key upshot.

Gluing the Patch

Once nosotros have a solid dry fit with tight joints we mix up our epoxy.

We use Due west Arrangement epoxy, a versatile two-part, marine-form epoxy that bonds and coats fiberglass, wood, metal, fabrics and other composite materials to provide superior strength and moisture resistance.

The epoxy was designed for boatbuilding and repair and works great on windowsills, columns and other areas where gluing, filling and shaping are needed.

We use the epoxy in 2 ways, equally glue and every bit filler. First we brush on the epoxy to all forest surfaces and then tap in the piece. It swells a bit, and a gentle hammer-tap confronting a wood block is needed to get the Dutchman in place.

Once in position, clench it or utilise a few well-placed end nails hold information technology until the epoxy dries—normally 8 to 24 hours.

Fill Any Voids

In one case the patch is installed, we mix upwardly a batch of epoxy with structural filler to fill up and overlap the seams of the patch and any nail holes created during the repair.

Sand Patch

We expect 24 hours earlier sanding the patch and applying a quality oil primer to the unabridged windowsill. The painter will follow us with additional primer and two-coats of paint.

Editor's note: Rob Robillard is a professional remodeling contractor and blogger at www.aconcordcarpenter.com.