how to build an archway

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

The moldings I used to make these pilasters you should be able to find at a local lumber yard that has a good molding & millwork department, or at a specialty molding retailer.

The flat-stock, of course, is nothing more than layers of mdf of various thicknesses.

The only materials I left out were the keystone and the ornate compo appliques, both of which I’ll cover in other posts in this series.

How Much Does Flex Trim Cost? Where Do I Buy It?

You can special-order Flex Trim from an online retailer or through your local lumber yard (if they are an authorized retailer.)

I’ve ordered it both ways, and honestly, I got the best price and the fastest shipping from an online retailer.

Most of the lumber yards I’ve ordered Flex Trim through would sit on the order until they could send it in with a batch of other orders, delaying the project significantly.

So if you order yours through your lumber yard, then ask for the specific day they will send it in so you know how long your wait is.

The online Flex Trim sellers I’ve dealt with send the order in immediately.

flexible moldings

Flex Trim details below.

Flex Trim Moldings c. $362.56 For Both Sides

This total price probably represents a minimum cost, but at least you now have a starting point.

I don’t have the exact dimensions for the arch any longer, but it is approximately 7′ of material. I will use that value when calculating the materials costs.

1. Backband CA-006  (c.$31.01 for 7′ for the arch) + ($17.72 for 4′ for the legs) = ($48.73 for one side)(2 sides) = $97.46

Note The rabbited portion of this backband was about 1/16″ too deep, causing the small cove to sit above the surface of the larger casing molding it’s mated to, and that left a small gap.

To fix it so this rabbited portion sat snugly on the casing, I trimmed it down on my table saw.

You will not have to provide a radius to Flex Trim for the backband molding because it will naturally flex correctly. The casing molding is another matter.

More about CA-006 here >>

2. Casing, Radius CA-005  (c. $84.35 for 7′ of radius) + ($48.20 for 4′ of straight pieces) = ($132.55 for one side)(2 sides) = $265.10

Radius Section Note  Because Flex Trim does such an excellent job on their website of explaining how to find a molding radius, I’m not going to repeat it here.

Straight Sections Note  If you are going to include the legs on your archway like I did here (you don’t have to, you can create a simple eyebrow arch without them), then you will need to order straight sections from Flex Trim.

Be safe and order plenty of extra. I added two feet for each leg.

Just follow their instructions and call their help line if you have questions. That’s what I always do.

More about CA-005 here >>

how to install archway moldings

Details below.

Arch Soffit $2.22

MDF-100  To make the soffit I cut about a 5″ wide strip from  4′ X 8′ sheet of MDF-100, of which you’ll only need about a 5″ wide strip. That leaves you plenty left over to use elsewhere.

Installation Note  I needed to give my soffit piece a little more flex to fit the arch, so I cut kerfs across the back. Worked like a charm.

More about MDF-100 here >>

archway moldings

Lower pilaster materials.

Lower Pilaster Materials c. $32.58

Base Cap  PM-002  To be safe, buy one 8′ stick for each side of the arch. $14.00/8′ stick (2 ea.) = $28.00.

More about PM-002 here >>

Base Fascia  MDF-300  This fascia I ripped 6″ wide from a 4′ X 8′ sheet of this material. That makes portion cost about $4.58.

More about MDF-300 here >>

pilaster moldings & millwork

Upper pilaster materials.

Upper Pilaster Materials c. $92.64

1. Echinus  PM-009  I used 1 ea. 8′ stick for each side = $25.60.

More about PM-009 here >>

2. Flat-Stock  MDF-200 I ripped a 1-3/4″ wide strip from a full sheet. That would cost about $8.48.

More about MDF-200 here >>

3. Bed Molding CM-001  I used one ea. 8′ stick for each side = $23.20.

More about CM-001 >>

4. Flat-Stock  MDF-300  I ripped about a 6″ wide strip from a full sheet, and then cut the pieces to fit. So that’s about $8.16.

More about MDF-300 here >>

5. Astragal  PM-013  I used one ea. 8′ stick for each side = $17.60.

More about PM-013 here >>

6. Screen/Bed Molding  I used 8 ea. 8′ sticks  = $38.40.

More about PM-004 here >>

arch columns

Pilaster Core Material $32.64

At the heart of these beautifully detailed pilasters is a core of 3/4″ thick mdf board. That’s it.

MDF-300  I ripped c. 7″ wide strips from one 4′ X 8′ sheet at a cost of $32.64.

Strips for Panels c. $5.38

MDF-200  To make the frames for the inset panels on the face of the pilasters, I simply ripped some strips of 1/2″ thick mdf, about 1″ wide, and then glued them in place. Easy. c $5.38 for 9 ea.

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