What is Trim Capping? Advantages of Trim Capping

Never want to paint again? Use trim capping

Does your home need an exterior repaint? Maybe it just needs touching up on the outside trim, especially around the windows, doors and eaves where the elements hit hardest. Painting any space can be an expensive and time-consuming task.

Regardless of your location, your home’s wood siding or exposed wood trim is going to require ongoing maintenance. Properly installed and carefully treated wood is an excellent exterior finishing material. Wood has been used to construct and clad thousands of homes across America for hundreds of years.

Many wooden homes that are centuries old look fresh and firm as the day they were built because they were taken care of and repainted. Proper care of wood window casings, door moldings, fascia and rakes can fend off decades of wear from sun, wind, rain and ice.

In busy times where budgets are tight, repainting your home’s trim is something you might want to avoid. Low maintenance is more than a current buzzword, It’s a condition many homeowners strive for. Maintaining exterior wood trim requires careful attention to detail, considerable exertion and plenty of time.

Trim painting can be a difficult do-it-yourself task. Hiring a professional for your painting needs allows you to relax and rely on quality work that will last and pay off in the long run.

Luckily, there is an easier way to maintain your exterior trim that will give you a long-term return on a one-time investment. It’s the simple solution to give exterior finishes a long and maintenance-free life: trim capping.

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What Is Trim or Window Capping?

The term “capping” or “wrapping” refers to cladding your home’s exterior trim with a durable, weatherproof and long-lasting material that simulates the original finish and color. Synthetic materials like aluminum or vinyl are cut and shaped to the same profile as your trim and set over top. The wood window, door, rake and fascia casings are then “encased” in a maintenance-free material.

Trim capping, or window capping, is an exterior finish technique that’s been used for years. Trim capping windows with vinyl or aluminum is especially popular in colder climates like the northeastern states where severe weather takes its toll on exposed wood trim. Many homeowners consider trim capping as the perfect, long-term solution for keeping their outside maintenance down and their curb appeal looking great.

Gone are the days of scraping and sanding layers of paint off weather-beaten boards. There’s no more climbing to elevated heights on flimsy ladders or scabbed-together scaffolding or to shell out hundreds of dollars for piles of material or hours of labor. Once a home’s trim has been capped, it’s there to stay.

The purpose of trim capping extends beyond cutting routine maintenance and keeping up looks. Capping actually protects the wood’s integrity. Capping provides a strong barrier that prevents elements from getting into the wood. Are you still wondering, “Should I use trim capping?” Consider then that trim capping is like an armor coating. It acts like a jacket of protection.

Trim capping provides significant returns for your home. Primarily, you will benefit from:

  • Low or no maintenance for years to come
  • Protection from elements that wear and rot wood
  • Isolating trim from insects such as termites and beetles
  • Resistance from fire, frost and freezing
  • Excellent appearance for a continuous “just-painted” look
  • One-time cost with long-term money savings
  • Convenience from continual time savings
  • Variety of material and color choices

Capping refers to cladding your home's exterior

How Does the Capping Process Work?

Part of making the choice in having your home’s wood trim capped is understanding how the capping installation and treatment process works. It’s actually a simple and relatively quick undertaking.

To start with, you need to select the suitable trim capping materials. Trim capping with aluminum sheet stock is the most popular product choice. Various brands of aluminum stock come in different thicknesses or gauges. Aluminum trim capping is available in a wide variety of colors and several different paint applications. Capping materials also include color coordinated finishing nails, adhesives and caulking.

Trim capping with vinyl or polyethylene products are not as popular as aluminum. Vinyl has its place and has an impressive ability to simulate wood’s natural grain and surface patterns. Aluminum, on the other hand, is flat, smooth and has different light reflecting capabilities depending on its surface. Aluminum capping material comes in flat, semi-gloss and high-gloss finishes. Aluminum is also available with painted or baked-on enamels.

Most professional trim capping contractors prefer to use a high quality aluminum stock such as the Alside G8 High Performance Coil. This top performing product comes in rolls of thin metal that lay flat when unwound and is capable of being bent into most shapes that match your window, door or other exterior trim profile.

An impression or exact-sized model of the trim is made and the shape is followed as the aluminum coil sheets are fed into a mechanical device called a “break”. Breaks are specialized tools that skilled craftspeople operate. Adjustable breaks come in a wide variety of angles, bends and positions that let the flat metal pass through the break’s seams. The finished metal exits as a perfect profile to snap over the trim molding.

Metal trim caps can fasten to the underlying wood through a combination of techniques:

  • Friction is a main fastening source. The cap’s fit should be precise. The natural bonding pressure between wood and metal is sufficient to hold most caps in place without assistance.
  • Nails are a secondary form of securing. Small metal nails anchor the caps in place and provide resistance against wind or curious hands. Cap nails come in the same color combinations as the aluminum coils.
  • Adhesives glue the trim caps in place. Specialized contact cements can help secure trim caps in place. Care and conservativism is the key to adhesives.
  • Caulking surrounds seams and openings. Color matched, malleable caulking is popular to fill small holes where metal joints leave exposure for water, dust or insects to ingress.

Difference Between Vinyl and Aluminum in Trim Capping

Trim capping can be done with either vinyl or polyethylene products or aluminum, but aluminum is typically the most widely used.

Vinyl has an impressive ability to simulate wood’s natural grain and surface patterns, but it typically works better for applications like siding. Vinyl trim offers color variations like white, grey, tan and brown, and many brands offer either gloss or matte finishes.

Aluminum, on the other hand, is flat and smooth and has different light-reflecting capabilities depending on its surface. Aluminum capping material comes in flat, semi-gloss and high-gloss finishes and is also available with painted or baked-on enamels. Additionally, aluminum comes in different thicknesses or gauges depending on what’s best for the job at hand. Various brands of aluminum stock offer different gauges. Aluminum trim capping is also available in a wide variety of colors and several paint applications.

Most professional trim capping contractors prefer to use a high-quality aluminum stock such as the Alside G8 High Performance Coil. This top-performing product comes in rolls of thin metal that lay flat when unwound and can bend into many shapes to match your window, door or other exterior trim profile.

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Signs You Should Cap Your Windows or Replace Trim Capping

If your trim is looking worn down or you don’t remember the last time it was replaced, it’s probably time to get some work done on it. If you look at the wooden exterior trim around your windows and the wood doesn’t look good, it’s definitely time to look into trim options. Window trim needs to be revitalized every so often, and there will be telltale signs of damage — both outside and inside your home. Signs of trim damage to look for are:

  • Rotting of the exterior wood
  • Cracks in the wood
  • Interior wall stains
  • Mold and mildew around the window
  • A draft coming from windows
  • Increasing energy bills, especially in winter

If you notice any of these issues occurring, it’s highly likely that your trim needs to be refurbished.

When thinking about new exterior trimming for your windows, it’s important to look into both replacement options and capping options. While either will fix the problem, you’ll want to consider trim capping if you want the most cost-effective solution. Capping protects your exterior, looks great and safeguards your home’s interior.

It’s also necessary to have a professional do your exterior window capping. Since the project goal is to ensure no air or water gets into your home, hire a professional — only trained experts know the best practices to prevent further issues from occurring.

How Is Color Matching Done?

Color matching is a key part of selecting the right material for your trim capping. Professional contractors who use the Alside G8 High Performance Coil have a choice of 16 different classic colors that have a wide array of rich hues that reflect timeless beauty.

Where a stock classic color isn’t suitable, custom coloring can be done using standard, primed aluminum stock. Professionals who are familiar with long-lasting metal applications can do a custom paint job. Custom painting considerably adds to the expense so you may find a compromise using stock colors. It’s rare to resort to custom painting.

Factory finishing on the G8 High Performance products is exceptionally durable. Ratings by the ASTM Physical Performance Standards find that G8 stock outperforms other coil finishes from competitor products. These trim cap components stand up to the profile process while being formed in the break, whereas materials mark and mar from the stress of bending pressure. G8 caps go on pristine and stay that way for years to come.

Color protection in G8 High Performance coils guarantees built-in stain inhibitors. Dirt, oil, tree debris and all forms of pollution can stain or damage your home’s trim if not protected. With G8 coils, your color selection is kept looking new with only the occasional hosing or wiping down.

Trim capping is a highly specialized skill

What Specialized Skills Does a Trim Capping Installer Need?

Capping wood trim on a home’s exterior is a highly specialized skill. This is not a do-it-yourself undertaking where you can rent a break, buy some aluminum coil and tackle it with your friends on a weekend.

Making the trim profile is critical to properly fitting caps. This takes a special eye and a talent for detail. Complicated wood moldings can have a number of angles, steps or even curves in their profile. Duplicating these profiles is tough but craftspeople trained in the process and equipped with the proper tools can get the job done.

Trim capping professionals are usually part of a specialized exterior finishing company. Their investment in expensive sheet metal breaks, service trucks, elevation equipment and installation tools is considerable. Even keeping inventories of colored aluminum coils is a heavy overhead.

A good trim cap installer goes beyond making the right profile, snapping it in place and making sure the caulking is right. Metal is a finicky material and needs sizing care depending on the installation temperature. Expansion and contraction joints are mandatory in metalwork. They prevent buckling from excessive heat and separation in icy conditions.

A skilled trim cap installer knows that on a 12-foot run, aluminum will generally expand about a quarter-inch when exposed to the sun or high ambient temperature. The opposite is true during freezing weather. Trim caps installed without attention to metal’s inevitable expansion and contraction is sure to leave you with a mess once the season changes.

Water is wood’s biggest enemy. Professionals are able to install trim caps with the knowledge of the properties of wood and the expertise to install trim caps efficiently , protecting your trimming from damage.

Replace rotting wood trim

What Water Damage Control Needs Doing Before Capping Trim?

Covering water-damaged or rotting wood with metal can be disastrous. No competent and skilled trim cap installer would think of covering wet, decaying wood trim with tightly sealed metal.

Although wood is an excellent exterior building material, it is highly susceptible to moisture’s effects. Shrinking, swelling, cracking, splitting and rotting are all part of nature’s design for wood. Rotting is simply a natural end for all species of wood and is part of the environmental recycling process.

Stopping water ingress is the primary reason wood trim is painted. Adding aesthetic value is secondary. Improperly treated wood allows moisture into the pores and begins the rotting process. Covering rotting wood with layers of paint or tight metal capping stops air movement, which is critical to drying wood and controlling decay.

You must also replace all rotting wood trim before capping. This is fundamental. Capping might disguise decay but will not ultimately stop it. The opposite occurs. Capped wood trim that retains or introduces water will accelerate rotting.

It is critical to deal with water damage before covering your trim with caps. Here are six simple and effective ways to treat wood trim and install caps to ensure long building life:

  • Remove and replace any rot damaged trim pieces
  • Allow surface water to dissipate before capping
  • Ensure new, raw wood trims are treated on all sides before installing
  • Create positive drainage at the bottom of trim caps
  • Use a shingle-effect for cap overlaps
  • Ensure flashing is in place at window and door heads

How Much Does Trim Capping Cost?

This is a difficult question to answer categorically. The costs of trim capping depend on a number of factors that apply to particular situations. Some of these cost factors include:

  • Building design complexity
  • Extent of trim profile
  • Type of materials selected
  • Area of installation
  • Number and length of trim pieces to be capped
  • Height from ground and difficulty of access
  • Mobilization time and distance
  • Fluctuation of material and labor pricing
  • Experience and skill of contractor selected

Cap pricing estimates vary among applicators. Some use an aggregate price based on the number of openings requiring capping. Some work on a rule of cost per linear foot. Some installers prefer to work on a time and materials basis where complicated projects are difficult to estimate.

The best approach to determining a proper price for trim capping your home is to select a trim capping professional and work together for a fair price.


How to Clean Your Exterior Trim Capping

If you’ve gotten trim capping and want to restore it to its original shine by doing some cleaning, follow these cleaning do’s and don’ts:


  • Use gentle products such as water, soap and vinegar that won’t damage your trim’s finish.
  • Use a non-detergent soap.
  • Use a sponge or scrub brush with soft bristles to remove any stubborn debris.
  • Wipe the surface with a soft, fabric cloth.


  • Use harsh chemicals or abrasive cleaners, such as anything with alcohol, ammonia or bleach, that will damage your trim’s finish.
  • Use detergent soap.
  • Use steel wool, harsh scrubbers or anything abrasive when removing debris.
  • Wipe the surface with a paper towel.

If you want to clean your trim capping, use one part distilled white vinegar and one part warm water as a cleaning solution or 1 tablespoon of non-detergent soap with 4 cups of warm water. Saturate a sponge or soft scrub brush in the solution and use it to wipe away dirt and debris. When finished, wipe and dry the trim with a soft cloth.

How do I Select a Trim Capping Professional?

It takes careful research to select a home improvement and remodeling company that knows correct trim capping techniques, uses the proper materials and performs long-lasting work. That company has to have experience, skills and professionalism.

At Sunshine Contracting Corp, we are confident that once you investigate these factors you’ll find our company stands far above others. Sunshine Contracting has nearly 30 years of experience in all forms of exterior building projects, including trim capping. We use the same skilled craftspeople for every installation, unlike other companies that subcontract their installations. This creates a consistency and avoids improper work that causes service issues down the road.

Sunshine Contracting Corp offers a wide array of exterior remodeling services for all of Northern Virginia.

Some of the services we provide are:

From roofing to siding to windows to doors, Sunshine Contracting Corp provides quality, professional work that improves the value of your home and helps it retain its beauty and durability for years to come. Contact Sunshine Contracting Corp for your next outdoor home improvement project.

*Updated 12/01/2021


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