How to Trim an Arched Window (The Easy Way)

Arched windows and doorways can be beautiful – but how do you trim an arched window? It’s easy once you know this trick for curved molding, so read on to learn all about it!

You’ll also want to read How to Install Your Own Trim and Molding to Save Thousands of Dollars, and learn how to install craftsman window trim and how to case a doorway, too.

DIY Arched Window Mouldings

You may have noticed… and I’ve mentioned it a time or two… that I love molding. Nice thick sculpted molding just adds joy to my life and my home. A well-trimmed window is just easy on the eyes, you know? So when Jill shared how she installed trim on her arched windows… well, I swooned. 

If you’re wanting to update the look of your home, dressing up the window and door trim is a relatively inexpensive and easy update. A fresh coat of paint works wonders on unpainted wood trim:

Or you can add extra molding for a thicker trim, like I love!

Or, if you’re happy with the window trim, you can always try a new window treatment, I suppose… although that’s not near as much fun! (Check out 50 of our favorite window coverings to get inspired.)

And now, here’s Jill. You might remember her from her fabulous custom DIY range hood. Give her a warm welcome! She’s here to dish on how she trimmed her curved entryway windows and took them from flat craftsman trim to curvy moulding to match the picture frame trim she added later. This method would work great for a door archway, too!

How to Trim Arched Windows

by Jill from The Rozy Home

Hi everyone! It’s Jill from the Rozy Home! I, too, am a Remodelaholic. For the last three years I have been working non-stop on my home.

Last year I spent a large amount of time, effort and, yes, money, on my foyer. After all, the foyer is the first thing you see when you enter a home.

After adding board and batten (and then converting it to picture frame moulding) I decided that I needed to do something about my poor, naked windows. Most windows are easy to dress up with trim… with the exception of the half circle window trio I have here.

That happens a lot around the Rozy Home. I make one area beautiful and then have to fix something next to it because it stands out like a sore thumb! Because the windows were arched, I wasn’t quite sure what to do. I started by trimming the lower half of the windows in nice straight lines…

Pretty rough, right? Needless to say, they didn’t stay like that long. I scoured the internet trying to figure out how to trim the arches when I stumbled across a local craftsman who could make the arched molding for me to my specific inside dimension.

Within a few days, I had the flat craftsman trim arches in hand and went about adding them. They attached to the drywall with brads just like any other kind of trim, no special installer needed (just fill the nail holes).

Nowadays (a few years later), there are readily available pre-made arch trim pieces, too, if you have standard size windows.

The full DIY alternative could have been to piece together many many trim pieces in an arduous process to make the curve. Or use thin strips and a bending form and some DIY skills I do not have… Or to cut my own from maple or other high-quality plywood to fit the radius and width dimensions of my windows, probably after making my own trammel jig to cut the circle on a router table… or something like that, I’m not really certain.

That is to say – I was happy to decide that the best method for me was to save some time, money, and DIY frustration and pay a local craftsman to do this part for me.

The windows stayed like this with the flat trim for a couple of months. You see, dealing with arches is/was one of the most stressful projects I have done. The curves and lining everything up drove me batty!

But after converting the board and batten to picture frame moulding (by adding small corner round), I had to update the windows to match. I’ve already replaced the trim in most of the house and wanted to make the trim in the foyer coordinate.

Since I already had flat stock trim up, I needed to get creative. How could I trim the arched window to make the flat trim match the beautiful carved molding elsewhere?

One day, while walking the aisles of Lowes, I ran across EverTrue flexible trim. I thought it would work perfectly. (Update: EverTrue trim is no longer sold at Lowe’s, but you can find Flex Trim at Home Depot online or on Amazon.)

I picked up some of this flexible trim and took it home. Once I got home, I tried to recreate the pattern on the trim throughout the rest of the house.

 Much to my pleasant surprise, all I needed to do was glue two pieces together with LiquidNails adhesive and I was able to recreate one side of the current trim.

 Here is a side-by-side of the flat stock with and without the EverTrue flexible moulding:

 After gluing all the pieces, I glued the bendable pieces to the interior side of the flat stock trim. Next I glued a single piece to the exterior side.

For the arches, I had to nail the trim on. The angles/bending made it impossible to glue on. After a day of letting the glue dry completely, I began working on the corner of the arches. For this, I grabbed some old moulding I had in the garage and created a cornice-type piece.

Although I loved the look, the exterior side felt a little unbalanced. My solution? Head back to Lowe’s where I purchased more EverTrue, but this time I bought flat lattice. I glued it on the exterior edge of the trim and that did it. The trim was balanced!

 Here is the final product:

As far as the cost… The EverTrue trim was around $2.50 per 10 foot piece and I used about 30 pieces (for doors at window). The lattice was $5.00 per 10 foot piece and I used 10 – 15. If memory serves, the total cost was a little over $100. Not bad for trimming out 5 windows and two doors in a room with 15 foot ceilings!

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Wow, Jill — I love it! Makes my heart go pitter patter looking at your gorgeous entry and all that molding 🙂

Head on over to The Rozy Home to see more of Jill’s fabulous DIYs and her beautiful home.

More DIY Window Updates

• Lace DIY Window Film How-To
• How to Build a Custom Window Cornice
• No-Sew DIY Magnetic Curtain for a Half Door Window
• How to DIY Faux Stained Glass
• DIY Custom Window Mullion Grids

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Published 8 Feb 2014 // Last Updated 29 June 2024