We are doing a complete update of a 1975 home. The issue we can't figure out is in the living room. There is a drywall-wrapped beam at peak of vaulted ceiling that is 24' long. We want to wrap it with wood but have discovered it is inconsistent in every way possible... it sags in the middle (can't visually see it), the height varies, etc.

With being so long we can't build it first and install. But if we do it piece by piece on the beam nothing matches up because it isn't straight and equal across the beam. How do we do this???

We currently have 4x8 sheets of birch we were intending to cut and nail. Any suggestions would be so appreciated b/c we have brainstormed for weeks and searched all across the web and no ideas. Thanks!

  • 2
    Since the beam can't actually be made of sheetrock, have you checked to see what is underneath? Steel? Wood? May 15 '19 at 18:36
  • What is the maximum variation? i.e. How far does it sag, bow, or twist?
    – Valkor
    May 16 '19 at 13:51
  • From my memory of being in the attic, I think it is a laminate beam. I am not that concerned with the sag since it is a long span and old house. It is structurally sound, just being a pain cosmetically. I would say that it 'bows' from side wall to middle maybe couple inches. Hard to measure that. Also if we measure the height of the beam itself, there is some variance of about 3/8 inch. So in other words, the top line is not straight and neither is the bottom. But since the wood cuts need to be straight, I don't know what to do. May 16 '19 at 18:22
  1. With a helper, pull a builder's line (dryline) from one end to the other along a bottom corner of the beam. Find a good compromise that's just outside all the curves and humps. Fasten the line to the walls at each end and make sure it's very tight.
  2. Check that you can plumb up from the line at all points along the beam without encroaching on the beam. If not, move the line outward as necessary to clear the beam.
  3. Check the line for level and square with the room. Adjust as needed.
  4. Set another line on the other side of the beam parallel to and level with the first, again just outside the beam's extremities.
  5. Plumb up from both lines at the four ends and mark the ceiling. Snap chalk lines along the ceiling to establish straight lines at the top. Pull the chalkline perpendicular to the ceiling when you snap it to prevent curvature due to a non-flat surface.
  6. At 16" intervals, fit and install shims, cut from two-by lumber, around the beam that come just shy of both lines and the ceiling marks. Don't touch the line or you'll push it out. This has a cumulative effect and will result in curves. Each set of shims should result in a plumb, level, square panel mounting base.
  7. Install your panels over the shims as though they were a framed wall.
  • Just thought I would let you know that although we didn't do the project exactly as you suggested, another version of it let us finish it successfully!! Well, almost. We ran out of time but the sides are up level and plumb. Putting the bottom on will be an easy day! I am so glad to have this crossed off my list of projects. Thanks for your suggestions! May 20 '19 at 16:58
  • You're welcome. Please take the tour if you're not familiar with what's expected of you on this site.
    – isherwood
    May 20 '19 at 17:03

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