Lighting – Will a ledge of drywall get deformed with time

drywallrecessed-lighting

I'm planning to install new lights in our living room. There's an existing support beam that I'd like to use as base for a drywall ledge where I could install my spots.

A side view of the idea looks like this:

The beam is solid and I don't want to drill in it, some I'm thinking of gluing a border to drywall (alternatives?) using good mounting glue.
Will the drywall keep its flat shape in this configuration or will it get deformed with time?
Should I add supporting L-brackets at some regular interval?
Any other factors that need consideration?

Best Answer

Oh it will sag so bad! Use piece of MDO or birch plwood with a glued on or iron on edge, if you need to keep the thin edge. If the run is over 8 ft. glue the but joints with a biscuits or spline. 3/4" plywood will work best for this and you can profile the glued on edge in this case to a smaller profile if you want it thinner than 3/4"

If it is a matter of preferring it to be in the beam, but do not want to ruin its integrity, you can box it in with drywall, add a nailer on the ceiling and create a wider box to hold the light beside the beam, but contained in an enclosure. If the beam is structural and esthetic, you may be able to re-wrap the beam in the same wood and finish, just make it wider.

Light shelf