Guide To Capping Windows

Our guide to capping windows will go through the basics, process and costs associated with capping a home window. Many older homes have an exterior wood casing or molding around the windows that require periodic painting to insure that the wood does not rot or deteriorate. Capping is the process of covering and completely sealing the wood casing to both protect the wood and create a maintenance free window covering.

Cost of Aluminum Capping

Capping an exterior window will vary based on the materials used and the size and condition of the wood molding. The general price range is $50 to $125 with $75 per window being the average cost. For additional costs, check out our replacement window costs page.

-- Price Range: $50 to $125 per window --

Typically, capping is done with either a vinyl coated aluminum or using PVC trim coil. Each piece is custom sized and cut using a specialized tool on the job site to fit the window trim. The outside edges are then caulked with a high quality silcone sealant to create a watertight seal. The result is a nice looking exterior window trim that is virtually maintenance free and should last for 20 years or more.

Type Of Window
Frame Material
Quality Of Window
Type Of Installation
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Opinions On Aluminum Capping My Windows

Thanks Jim. One last question. The Marvin dealer wants to use aluminum capping on my exterior wood window trim versus a full gut and replace of the exterior wood trim with PVC. Do you have an opinion about aluminum capping of exterior wood trim?

Nick - Homeowner - October, 2021

Website Editor's Answer

Nick, when the aluminum capping is done right, it is very effective at protecting the windows from water damage. This video shows what is entailed in the process and is worth a quick look in my opinion.

I'm not sure what I think of the look personally. It really depends on the home, the age of the home, the overall quality of the home, the surrounding materials, etc.

Editor Jim - October, 2021

Window Trim Capping Question

Hi Jim. One more thing that I do not quite understand.

Do you recommend doing capping of a window trim?

The installer I am talking to said he will do install of windows from inside as outside install compromise the trim and he does not recommend the capping as it can create mold and water issues down the road.

I have not found a lot of research on that. For me capping is more saving on pairing and can improve esthetics of the windows if you are looking for more contemporary straight lines.

Thank you for your valuable insights.

Vlad - Homeowner - May, 2021

Website Editor's Answer

Vlad, capping your trim simply protects the exterior wood trim. Properly done, it shouldn't create problems (just the oppoiste), but improperly done then he is correct. It really depends on the condition of the window trims. Some people paint every five years or so and some homeowners don't want to deal with the hassle...

Capping does make for a cleaner look. Decide if you like the look and if so, make sure that the installer who will be doing the capping feels really comfortable with the process and does it enough that he is going to do a good job.

Editor Jim R. - May, 2021