What is exterior window trim called?

Exterior window trim, also known as window casing or exterior window casing, refers to the decorative molding applied around the edges of windows on the outside of a house. It serves both aesthetic and functional purposes. Aesthetically, exterior window trim adds visual interest, provides architectural detail, and frames the windows. Functionally, it protects the windows from weather damage and hides any gaps between the window frames and the walls.

Names for Exterior Window Trim

There are several common names used to describe exterior window trim:

• Window casing – The most generic term referring to any type of trim around a window.
• Exterior window casing – Specifies that the casing is on the exterior side of the window.
• Window surround – Refers to more ornate, decorative trim around a window.
• Window exterior trim – Another way to specify exterior-mounted window trim.
• Window header – The horizontal top piece of trim above a window.
• Window jamb – The vertical side pieces of trim on either side of a window.
• Window sill – The bottom horizontal piece of trim below a window.

While “exterior window trim” or “exterior window casing” are broad terms for any type of outer window framing, terms like “window surround” and references to header, jamb, and sill describe more specific components of the trim. Nevertheless, all these terms fundamentally refer to the outer decorative framing around a window.

Materials Used for Exterior Window Trim

Exterior window trim can be constructed from various materials, each with their own attributes in terms of durability, maintenance, cost, and aesthetics:

• Wood – A very common choice, available in different grades and types like pine, cedar, and mahogany. Offers natural beauty and versatility for shaping trim details.
• Vinyl – PVC exterior trim is moisture-resistant and low maintenance. Offers a more limited range of shapes and sizes.
• Fiber cement – Made from wood fibers and cement, this material is strong and weather-resistant. Can be shaped and painted to achieve wood-like aesthetics.
• Composite – Composites like cellular PVC can be carved and shaped like wood but are more durable.
• Polymer/foam – Lightweight synthetic trim options that are easy to install but less durable than other materials.
• Metal – Aluminum and galvanized steel trim withstand weather well but require more caution during installation to avoid corrosion..

Wood remains the most popular choice in many cases, but several alternate materials are also common for exterior window trim, with their own advantages and disadvantages.

Styles of Exterior Window Trim

Some of the most common architectural styles used for exterior window trim include:

• Simple casing – A basic, flat trim frame with minimal ornamentation.
• Brickmould – A wider, flat profile often used to border masonry.
• Backband – A plain, flat trim bordering the window frame on the exterior side only.
• Sill nose – An overhanging lip or drip edge at the bottom of the trim below the window.
• Pediment – A triangular cap at the window head, reminiscent of classical architecture.
• Crown molding – A stepped trim with a decorative rounded or angular profile.

Trim can also incorporate architectural styles like Craftsman, Victorian, or Colonial. More elaborate trim may layer multiple profiles for a built-up look. The style choices are endless, depending on one’s desired aesthetics and budget.

Typical Dimensions

While exterior window trim dimensions can vary, typical sizes include:

• Window casing thickness – Common options range from 3/4 inch up to 2 inches thick.
• Casing width/exposure – Often 2 to 6 inches wide.
• Brickmould width – Usually wider at 5 to 7 inches, up to 10 inches.
• Sill nose overhang – Typically 1 to 2 inch projection below the sill.
• Pediment height – From 6 to 18 inches tall at the center peak.
• Crown molding size – Profiles range from 1 1/2 to 5+ inches tall.

Larger window sizes or more elaborate detailing may demand thicker, wider trim surrounds. The dimensions should suit the window size, architectural style, and aesthetic goals.

Terminology for Trim Components

Some specific terms refer to the individual components that make up a complete window casing frame:

• Head casing – The horizontal top piece above the window.
• Jamb casing – The vertical side pieces flanking the window.
• Sill casing – The bottom piece below the window.
• Mull casing – Narrow vertical trim between multiple window units.
• Mullion – The structural framing element that divides adjacent window units.
• Stool – The interior sill or bottom rail of the window frame.
• Apron – A decorative panel below the stool and window.

Understanding these terms helps to identify the individual components that make up the full exterior window surround.

Tools for Cutting and Installing

Some basic tools required for exterior window trim projects include:

• Miter saw – For precise angle cuts
• Table saw – To rip trim boards to width
• Jigsaw – For curving or notching trim pieces
• Router – For cutting profiles like crown moldings
• Brad nailer – For attaching the trim boards
• Hammer – For tapping joints or nails
• Level – To check for plumb and level lines
• Tape measure – For measuring and cutting to size
• Utility knife – For trimming or notching materials
• Caulk gun – For sealing gaps and joints
• Wood putty – For filling nail holes
• Sander – For smoothing rough edges

Proper safety equipment like gloves, goggles, and a mask should always be used as well. Investing in quality tools helps ensure good results and makes the installation process easier.

How to Install Exterior Window Trim

Installing exterior window trim involves careful measuring, cutting, and fitting to achieve clean results. The basic process includes:

1. Measure the window height and width to calculate the dimensions for each trim component.
2. Cut the head, jamb, and sill pieces to size with precise 45 degree mitered ends.
3. Pre-finishing is recommended by painting or staining prior to mounting.
4. Fit the head piece first using finish nails. Check for level.
5. Install the side jamb pieces next, verifying they are plumb.
6. Add the sill piece last, confirming everything is square.
7. Caulk around the perimeter to seal any gaps.
8. Fill nail holes, sand, and touch up paint if needed.

The trim should sit tight to the window frame all around. Allowing adequate time for careful measuring and cutting ensures the casings meet neatly in the corners.

Costs

Exterior window trim costs depend on several factors:

• Material type – Composite and PVC cost more than simple wood trim.
• Trim dimensions – More complex profiles and larger sizes increase costs.
• Labor – Hiring a professional is faster but adds expense.
• Window count – More windows to trim raises overall project costs.

Very roughly, basic DIY exterior window trim costs might range from $5 – $20 per linear foot installed. Hiring a carpenter could run $50 – $100 per window opening. Using premium materials or labor on multiple large windows can quickly result in costs from $500 up to several thousand dollars.

Cost Comparison of Exterior Window Trim Materials

Material	Cost per Linear Foot
Clear pine	$2 – $8
Cedar	$4 – $12
Redwood	$6 – $15
PVC/vinyl	$8 – $20
Cellular PVC	$12 – $25
Fiber cement	$6 – $18
Primed MDF	$4 – $10

This table compares estimated material prices only. It does not include additional labor costs if hiring a professional installer.

Advantages of Exterior Window Trim

Some benefits provided by exterior window trim include:

• Protects windows from weather damage like rain, moisture, and drafts.
• Enhances curb appeal and architectural aesthetics.
• Frames windows and draws the eye to openings in the façade.
• Hides gaps between the window frames and the structure.
• Can mask a rough window installation if done well.
• Offers design flexibility with many trim profiles and materials.
• Can match the style of the home’s architecture.
• Relatively affordable way to finish off window exteriors.

Attractive, weather-resistant exterior window trim brings visual order to a home’s face while protecting windows in the process.

Disadvantages of Exterior Window Trim

Some potential downsides to exterior window trim consist of:

• Requires regular repainting or refinishing to maintain appearance.
• Can rot or warp if moisture penetrates unfinished wood.
• Provides ledges and crevices for pests or water to enter if not properly sealed.
• Some materials like foam or thin PVC are vulnerable to damage.
• Metal trim conducts heat and cold and requires insulation.
• Ornate trim styles take more time and skill to fabricate and install.
• Poor fitting joints or seams allow water infiltration behind siding.

Preventing problems comes down to proper material selection, sealing, and installation. When executed well, there are minimal downsides to quality exterior window trim.

Alternatives to Exterior Window Trim

In lieu of full window casing, some other options include:

• Backband trim – A simple trim border around the window on the exterior side only.
• Stool and apron – Interior sill trim only rather than full exterior surround.
• Drywall return – Sheetrock wrapped around window openings without decorative trim.
• No trim – Windows finished flush with siding or stucco with no decorative frames.
• Shutters – Operable or decorative shutters flanking window openings.
• Quoins – Stacked masonry or stone blocks at window corners.

Eliminating exterior trim entirely results in a cleaner, more minimalist look. For those wanting embellished windows, backband moldings or shutters still provide decoration without the maintenance of casing.

Conclusion

Exterior window trim serves both form and function for homes. While “window casing” is a broad term for any outer trim framing a window, many more specific profiles, materials, dimensions exist to suit the home’s architecture. Crafting tight-fitting trim takes precision but dresses up window exterior and protects them from weathering. For those wanting a more streamlined look, alternatives like simple backbands or no trim at all are options. With some careful planning and quality installation, decorative exterior window trim can be a beautiful and functional addition to accent windows and add visual interest to exterior walls.