Walnut Window Sills

What walnut is like

Walnut is the one species that does not need stain to look expensive. The heartwood runs deep chocolate-brown straight from the board, with a fine, even grain and occasional lighter streaks where sapwood meets heart.

It is softer than oak or maple — around 1,010 on the Janka scale against white oak at 1,360 — so it marks more readily. On a sill that is usually a fair trade, but it is worth knowing before you put one under a window that gets heavy use.

Walnut sills in place

The 7 walnut finishes

Every finish below is sprayed on walnut and shown on your own piece inside the configurator — not on a swatch card.

Choosing walnut for a sill

Where it fits

Rooms where the sill should be the dark note against pale walls. Reading nooks, bedrooms, traditional living rooms. It pairs particularly well with black window frames, where the sill reads as a continuation of the frame rather than a contrast to it.

Where it does not

High-traffic kitchen sills where things get set down hard. And walnut lightens with UV exposure rather than darkening, so in a very bright south-facing window it will shift over a few years.

Walnut window sill sizes

Cut to your opening rather than to a size chart.

Dimension	How it works
Length	Jamb to jamb, entered to 1/16", from 18" to 144" in one piece. A 1/16" reveal per side lets the piece drop into an out-of-square opening.
Depth	Wall face to window frame, plus your projection into the room. Most interior sills run 5" to 12".
Eared returns	How far the ends run past the opening. 2½" is typical; zero for a flush cut.
Thickness	3/4" slab, with a laminated build-up edge to read as 1½", 2½", 3" or 4" from the front.
Edge profile	All six profiles machine into walnut: eased, bevel, radius, cove, ogee and Roman ogee.

Related guides

• All hardwood window sills
• Window sill edge profiles explained
• How to measure a window sill
• Wood vs solid surface window sills