ceilingconstructionmeasuring
I am building a tray ceiling for my living room to install recessed lighting in. Is there any general ratio's for tray size to room size? I have looked everywhere and it seems most tray ceilings don't follow any guidelines.
So, the room is 12 ft x 16 ft and 9 ft ceilings. So how do I calculate the size tray to build?
If no size to room ratios are there any general height to depth ratios, like 1×2 (9 tall x 18 deep for example)
I agree with answer #1 with the following exception: Do not use longer screws to attach the fixture. Find a suitable box with extensions as needed to make the box opening flush with the ceiling surface. You do not want a gap between the box and fixture the could allow heat and spark from a fault in the box to escape. Here are products that I would use in your situation. These may not be available at home improvement store but are available at electrical suppliers who service contractors.
For support between studs -- Erico/Caddy TSGB24 or simply use a 2x4
Box attached to support --4" octogon box
Two extension boxes as need to bring opening flush -- 4" octogon extension box 2 1/8" deep
This combination gives you a box 5 3/4" deep. Adjust the support on the attic studs to make this flush with ceiling.
Remember that it is important to not leave a gap that could cause a smoldering fire in the voids of the ceiling structure. This is the reason that most electrical codes require that box faces be flush with the finished surface.
You can install a shallow 6" can made for 2x6 construction. Halo H27ICAT is the 6" you can use. Lots of manufacturers make these shallow cans.
You can use regular incandescent, fluorescent and LED lamps and have a large selection of trims. The only drawback is you can't use taller lamps or they might stick out the bottom. The most common is the 50PAR30 / 75R30 style lamps. These are also made in remodel style in case the ceiling is already up.
Here is the spec sheet for the H27
EDIT
I'll give this another try. I originally deleted this answer because it is not a slope can. Where I work, some people use regular can lights and use adjustable trims. Because of the depth you have, 8 inches, this can is 5-1/2 inches. I suggest you use a gimbal ring trim. It works like a eyeball, but the lamp is recessed so you don't get that 'bug eye' some people associate with eyeball trims. You can get the above can in 5 inch or 6 inch round cans, both IC rated, depending on the manufacturer your supplier uses. Think about a trim like this.
Make sure you use the same manufacturer as the can and trim to cover yourself. This gives you 2-1/2 inches for your channel and insulation. If this doesn't float your boat try going to a local lighting showroom and look at what they might have. If you want recessed you will find what you want. Consider LEDs to keep from getting the ladder out if your slope gives you a tall ceiling. While considerably more, doing it all together will be less painful. Either way PAR30 Halogen or PAR30 LEDs offer different beam spreads, so you can at least do something with the lighting.The biggest problem is you can't shine the light back to the wall, mostly straight down or with the angle the can is hung, not backwards. If you choose this, don't forget the dimmers!
Best Answer
It's pretty much up to you. Look at some pictures, find ones you like, make guesstimates.
When in doubt and looking for a ratio, there's always Phi (0.618) and 1/Phi (1.618) aka "the golden ratio" but you're still free to do with it what you will.
When you think you have an idea, grab some masking tape and mock up the outline on the ceiling (I'm assuming the ceiling is there, and flat, at the moment.)
While it would be difficult to mock up the whole edge, you probably can suspend a sheet of cardboard at various heights (I assume you are lowering the edge, not raising the center, as that's more structurally simple) to get a feel for how various levels for the lowered edge feel to you, standing under them. If you find that a 7'6" ceiling height (18" down from 9 feet) feels too low, better it's a piece of cardboard you can easily relocate than the whole framing system and drywall.