Valance Installation

[theracqueteer]

Today I removed one of our recliners in the slide-out. After removing it, we noticed that it had worn the fabric on the cornice box that goes down the side of the window and behind the recliner. So, the DW wanted it removed so, that we could recover it. When I removed it along with the one on the opposite side, the valance fell down. The cornice boxes were the only thing holding the valance up as none of screws going in the ceiling hit anything solid. My question is, at what spacing are the ceiling joists spaced in the slide-out?

There is not a lot of room to work or use a stud finder. There is a joint in the ceiling that I would think breaks on a joist. If so, and if I know the spacing, I can mark the valance so that I can hit the other joists. My guess would be they are 2'OC.

[theracqueteer]

In case someone else is interested for their project sometime, I figured out the joists in my slide-out are roughly 16" OC.