Count on 30 to 80 millimetres behind the ceiling, depending on the spot. The shallowest we carry needs 27 millimetres, an ordinary recessed spot easily double that. So measure how much room you have first and choose the spot after, not the other way round.
What recess depth actually is
The recess depth is how far the spot protrudes behind the ceiling. That is a different thing from the cut-out size, which is about the width of the hole. Two spots with the same 68 millimetre cut-out can therefore be very different in depth.
Where it goes wrong is that people look up the cut-out size, cut the hole, and then find the spot will not go in. The hole is already there by then. Which size to cut is in What cut-out size do you need for recessed spotlights?
Measure first, then choose
You need three numbers before you order anything.
- The free space behind the ceiling. Drill a small hole and push a piece of wire in until you feel resistance, or take out an existing spot and measure.
- Where the joists and pipes run. A void 100 millimetres deep is no help if a joist or a water pipe runs exactly where you want the spot.
- The recess depth of the spot you have in mind. That is in the specifications.
Leave some margin on all three. The cable and the connector have to fit too, and a spot that fits exactly is a spot you have to force in.
When there is little room
That happens more often than you think: a timber upper floor with joists, a ceiling sitting straight against the structure, or a home where the previous suspended ceiling has been taken out.
There are spots for that with a limited build height. The Lyvo has a recess depth of 27 millimetres with a cut-out of 68 millimetres, and that is about the lower limit of what exists. The full range is at recessed spotlights with a low recess depth.
With spots like that, note that the driver often comes separately. It has to go somewhere too, and it is usually thicker than the spot itself. In a tight void you lay it beside the hole rather than above it.
When there is no room at all
With solid concrete, or a ceiling sitting directly on the structure, recessing stops being an option. There are then two ways: a surface-mounted spot screwed onto the ceiling, or a suspended ceiling that creates the void after all.
When that comes up and what the alternatives are is in Can you fit recessed spotlights in a concrete ceiling?
When replacing: measure the old one
If you are replacing existing spots, the old spot is your yardstick. Take one out, measure the cut-out and the depth, and search on that. If the new spot is deeper than the old one it will not fit, even if the cut-out matches.
If the new spot is wider on the outside, that is not a problem but an advantage: a larger rim covers a hole that has come out slightly too big. How to go about that without wrecking the ceiling is in Can you replace recessed spotlights without opening up the ceiling?
The range is at recessed spotlights, with the recess depth in the specifications of every product.
What is the difference between cut-out size and recess depth?
The cut-out size is the width of the hole, the recess depth is how far the spot protrudes behind it. Two spots with the same cut-out can differ in depth.
What is the minimum recess depth of a recessed spotlight?
The shallowest we carry is the Lyvo at 27 millimetres. An ordinary recessed spot sits well above that, so measure your space before ordering.
How do you measure the space behind your ceiling?
Drill a small hole and push wire in until you feel resistance, or take out an existing spot and measure. Allow for joists and pipes in that spot.