No-Seam Faux Ceiling Beams

Advice on how to build and install fake ceiling beams with invisible seams. October 14, 2009

I am doing some faux box beams on a 24' ceiling. Any ideas for making a perfect seam without using a strap?

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor L:
My first thought was that at 24', almost nobody will see a gap of even 3/16". That said, we all aim towards some version of perfect. So, which seam are you referring to? The edges of the box beam? Some like lock-miters, some use butt joints. If the beams are stained dark or painted it makes no difference, in my experience. For all other seams, ordinary scribing works wonders. Everybody has their own methods, but I use a shorter piece of the same box-beam as a template to figure out the scribe angles, then, once dialed in, transfer it to the actual beam.

From the original questioner:
I'm sorry, I meant to say the length of the beam is 24' on a 10ft ceiling.

From contributor K:
I made a conference table and had to assemble on location. I used a magnetic fastening system called Invis. I assembled in the shop, sanded and disassembled then re-assembled on the job site. Couldn’t have worked any better. The fasteners are a screw system that works similar to a dowel with very good alignment. I saw it at IWF 2006 in Atlanta. Very ingenious.

From contributor C:
I am going to assume that this is a three piece box beam (2 vertical members, and a horizontal bottom). In order to index the pieces, you could put a tongue (with chamfered edges) on either side of the bottom piece, with a matching groove on the bottom edge of your vertical members.

From Gary Katz, forum technical advisor:
We do it frequently with pocket screws, before assembling the bottom and sides. Build up the beam on a work bench then cut and install it. Like contributor L said, use the cutoffs or make some short lengths to get the scribes down, then transfer those lines to the actual beam. We've also taken the short scraps to trace the beam outline on the walls, then used a Multi-master to cut the drywall or plaster out just where the beam goes. Shh, don't tell. Then you can slide the beam into the wall a little and get a very tight fit. The Multi-master doesn't vibrate and you can cut right to the outline of the beam. A little caulking - I mean a little - is all you'll ever need, even on stain-grade beams.

From contributor U:
At the company I work for, we make a lot of ceiling beams, often in light colors or even clear coat on 10-12 ft ceilings where mitering is the only option. (Unless you think you can get away with a MDF box and veneer! LOL) After surfacing, mitering, etc, we lay them across sawhorses (or anything else available). I have made clamping blocks by cutting 2 long strips of scrap, one cut at a 45, and gluing/stapling/screwing them together so it will cup the opposite mitered end (so it will not be damaged by the clamps) and gluing and clamping one side together at a time using pre-cut square spacers with pocket screws every 12 -15 inches or so to ensure sureness. Have had a lot of success with this approach. Also note: you will need an arsenal of clamps for this, which thankfully my shop has on hand!

From contributor O:
Box beams do not need straps. However, if you are doing a 24', you will have to use 12' boards, and the main problem we see is the grain. Our box beams are finger jointed, and then wire brushed. Using a hewn edge look can help as well. You also must consider the type of wood - Douglas fir is very hard to find in 1 by, and is usually not kiln dried, just milled 2 by with no further treatment, and the warping and twisting is prohibitive. Good luck hiding the different grains with the RS, and no wirebrushing these joints. I recommend cedar or alder.