Recessed lighting is a layout job first. The housings, the wafers, and the trims come after you know how the room is used, where the light has to land, and how it will be switched. The ten-second version: what does this room need to see, from where, on which switch — and is the ceiling open, finished, insulated, or already full of the wrong housings? Settle that before drywall goes back, or before anyone cuts a finished ceiling. A grid that looks even on a plan is often dark in the corners and bright on the sofa. There is no useful “one every four feet,” and buying the fixtures before the layout is how that grid gets ordered. Cans versus canless is a later choice — that comparison lives on recessed vs canless lights. Plan in this order: room use, then furniture and work surfaces, then ambient vs task, then switch zones, then ceiling type, then IC/airtight, then housings or wafers.
| Item | Current planning baseline |
|---|---|
| Layout | From furniture and work surfaces, not a grid |
| Spacing | No reliable “one every four feet” |
| Kitchen vs bedroom | Use decides the layout |
| Layers | Ambient vs task — not more downlights |
| Ceiling | Open vs finished vs attic access |
| Insulation | IC-rated and airtight where the housing sits in insulation |
| Switching | Zones and dimming belong in the layout |
| Cans vs canless | Follows the ceiling, not the catalog |
| Permit | New residential electrical circuits are minor-permit work |
That install is recessed lighting when a housing fits, and canless lighting when it does not.
Layout is not a grid
Even spacing is not even light. A living room with a sofa against one wall wants light on the seating and the path, not a chandelier of downlights over empty carpet. A kitchen wants light on the counters and the island more than on the face of the cabinets. A hallway wants a path, not a runway. Room size, ceiling height, and how bright the fixtures actually are move the count — there is no reliable spacing rule. Plan from furniture and work surfaces, then check joists. Do not plan from joists and hope the sofa lands under a can. A grid that looks even and lights nothing useful is the usual result of starting with a pretty drawing instead of the furniture.
A kitchen is not a bedroom
Use decides the layout. A kitchen often needs downlight on the work counters, the island as its own problem, under-cabinet lighting as a separate layer rather than more cans, and switching that can leave the room dim while the counters stay usable. A bedroom often needs less light, warmer control, and a way to not stare into a downlight from the pillow. A bathroom needs wet-location listings where they belong, GFCI on the required receptacles, and a fan that is not an afterthought — recessed over a tub is a listing question, not a prettier can. Do not copy a living-room count into a kitchen and call it a lighting plan, and do not use kitchen spacing in a bedroom. Different rooms. Different layers.
Ambient vs task — two layers, not more downlights
Recessed downlights are usually the room layer: general light from the ceiling. Task light at a counter, a desk, or a vanity is often a different product — under-cabinet, a sconce, a pendant over the island. Stacking more cans to “make the counters brighter” is how kitchens get glare and still have shadows on the cutting board. Plan the layers. Then the recessed count can stay honest. Under-cabinet lighting is not “more recessed.”
Open ceiling, finished room, or attic?
Three different jobs, same layout questions. Access decides the method. It does not decide the layout.
Remodel with the ceiling open. The cheapest time. Bar hangers land on joists. The layout is set before drywall. Move a can two inches now, or live with it for twenty years.
Finished room, no attic. Every hole is a commitment. Retrofit housings or canless wafers go in from below. Jagged or oversized holes do not hold a remodel housing. HALO’s remodel instructions are specific: the ceiling material is the support; the cut has to be clean. Do not cut a finished ceiling to “see if a can fits” — the ceiling type is checked first. Wafers exist because some ceilings will not take a housing.
Attic access. New-construction or remodel housings can go in from above where the attic is usable. Insulation still has to be IC-rated contact, not stuffed against a non-IC can.
Do recessed lights need to be IC-rated?
Where a housing sits in insulation, it has to be listed for insulation contact (IC). A non-IC housing in an insulated ceiling is a heat problem, not a trim choice — the listing has to match where it sits. Airtight (Air-Tite, ASTM E283) matters in conditioned Sacramento ceilings. HALO documents Air-Tite housings as meeting restricted-airflow rules such as California Title 24 when they are installed as listed — gasketed aperture and frame, not extra caulk as the product. IC and airtight are part of the housing choice. They are not an optional upgrade after the holes are cut.