ᐅ Installing Recessed Downlights in a Cast-In-Place Concrete Ceiling Without Plastering

Good morning everyone,

what is the best way to install spotlights in a ceiling if I don’t want to modify or plaster the cast-in-place concrete afterwards? We want to keep the concrete visible in the hallway on the ground floor to maintain the rustic charm.

I was thinking about using the Kaiser concrete slab ceiling large junction box. Fix it to the formwork boards with nails, pull the cables through, and that’s it. The spotlight to be installed should fit inside and the frame should cover the box.

Regards, Daniel

I have placed and dimensioned every spotlight, ventilation opening, etc., using a sketch and noted the installation housings to be used. For the recessed spotlights, I am using Kaiser installation housings designed for exposed concrete. For other openings, I coordinated the exact core drill size in advance to minimize patching.

Will it be a cast-in-place concrete ceiling, or are you using precast elements that are poured on-site?

However, I think you won’t be able to avoid some patching or cosmetic work entirely. At least, that’s what I am expecting. I can give you more information in about two months.

Hello Daniel

I do not recommend using nails. Make a template, mark the openings where the screws will go in from below (I have my empty boxes from the hardware store, which have these openings). Drill a 2mm (0.08 inch) hole through the formwork panels. Then fix the empty boxes from below with suitable screws (2.5 x 35mm (0.1 x 1.4 inches)). Tighten well, and you will have a perfect edge.

Steven

Hello Steven. Which boxes do you mean?

I need to check tonight. They were very cheap. I think under 4 euros each.

Hello

here are 3 pictures of the empty electrical box.
You can see the provisions for the screws I use to fasten the box to the formwork panel.
Maybe it would be better to use a spotlight with a slightly wider trim so that it fully covers the electrical box.
And then the nameplate.

Steven