backband molding

[This is part of my ARCHWAY-101 series.]

After installing the unwieldy arched casing, installing the flexible backband molding is easy.

Not just because it’s a small, easy to handle piece, but because it is not pre-molded into a specific radius.

And the keystone, primed and sanded already, is even easier to install.

The installation sequence is pretty basic.

If anything, let me remind you that, like almost all good finish carpentry, this is a cut-to-fit operation.

Let me also remind you that every single contact surface gets glued to it’s mating surface.

  1. Cut the vertical leg to fit. Install with glue and brad nails. With this piece securely fastened in place, you are now ready to cut and fit the piece that mates to it.
  2. Cut the arched piece to fit. Glue and install.
  3. Repeat 1 & 2 on all both left and right sides of each arch.

molding & millwork

diy moldings

diy moldings

diy moldings

Ken’s #1 Trick of the Trade

See how nice all of those mitered joints fit?

There’s no reason you can’t achieve the same results.

It’s all about being patient.

molding & millwork

Perfectly Solid Joints

Do you want to know what’s even better than perfectly mitered joints?

Mitered joints that won’t separate in the years to come.

In fact, because of the quality of Flex Trim and the industrial way I put this arch together, I’m sure the rest of the house would decay and fall down before this archway will.

Installing the Keystone

This is another sequence that’s so easy to do (because you built your keystone first and prepared for its installation) that it’s barely worth mentioning.

So I’ll make this brief.


Apply glue to the back of the keystone and insides of the arched moldings.

Not too much because you don’t want it to squeeze out between the joints.

Press your keystone in place. Leave it alone.

You’re now finished building your archway!

The Completed Archway

With a bit of planning and a lot of patience, you should now have an archway that looks something like this.

finish carpenter

How to Build ARCHWAY-101 Series

1. How to Build ARCHWAY-101 Part 1: Gallery

2. How to Build ARCHWAY-101 Part 2: Materials Inventory

3. How to Build ARCHWAY-101 Part 3: How to Make the Pilaster Core

4. How to Build ARCHWAY-101 Part 4: Keystone Materials and Layout

5. How to Build ARCHWAY-101 Part 5: Installing the Flex Trim Legs

6. How to Build ARCHWAY-101 Part 6: Installing the Arched Casing

7. How to Build ARCHWAY-101 Part 7: Flex Trim Backband & Keystone

8. How to Build ARCHWAY-101 Part 8: Prep & Paint