Everything You Need to Know About Window Sills and Trim

Get tips for choosing the right window casing, installing it and maintaining it properly.

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A window sill is the bottom piece of trim, or the ledge at the bottom of the window. While sills are a great place to put plants, they’re also a necessary part of the window, keeping out rain and making windows more energy efficient.

Sills are part of the window trim, which also includes the head casing, side jambs and the apron, the piece attached to the wall beneath the sill. Each plays a part in keeping the window structurally sound and the elements out.

Window Trim Ideas and Styles

Window trim is made to cover gaps and also add decorative appeal. It varies with home styles, from the simplest picture-frame trim to architecturally specific styles like Craftsman, Prairie and Victorian. One simple way to choose interior window trim is to match it to the home’s other molding, to ensure a cohesive look.

Because of their simple, straightforward design, ranch homes work best with an equally simple interior window trim. Here, a picture-frame trim style works well.

Wide, beautifully worked trim is the hallmark of Craftsman and Prairie style. Often these designs group windows together and case them in wide trim.

Victorian, Colonial, Provencal and English cottage styles are made for fluted trim and rosettes. The head casing, jambs and sill are often extended, with cornices for added style.

How to Install Window Trim

If you enjoy finish carpentry and have the right tools, installing window trim can be a satisfying job. For a full tutorial check out our video about installing custom trim. In the meantime, here are some tips to get you started:

·         Begin with kiln-dried wood or high quality precast foam, and measure and cut precisely.

·         Fill gaps with wood filler strips, not caulk.

·         Remove the pencil line with the saw blade; cutting right up to the line usually leaves pieces too long.

·         Trim the biggest windows first so that you can use leftover wood and miscuts on the smaller windows.

·         Keep nails more than two inches from the ends, to prevent splitting.

Cleaning and Maintaining Window Trim

An ounce of prevention and a little elbow grease will keep window trim in good shape.

Dust your window frame, especially the tops of sashes and window sills, each time you clean. Twice a year (or as needed), clean the trim with soapy water and let it air dry.

For mildew, spray a mixture of vinegar and water directly on the mold, and let the mixture sit. Wipe it until you can see the wood and let it dry. Then clean it with soapy water.

If your window trim develops water spots (window sills are especially prone to this as water can collect on the shelf), clean them with distilled water or spray on rubbing alcohol and wipe them down.

In damp rooms like basements and bathrooms, use a dehumidifier or open the windows to allow air to circulate.

Trim Tips for New Windows 01:07

Invest in new trim when installing new windows.
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