Too Many or Too Few? Calculate the Ideal Can Lights for Any Room
Installing recessed lighting, also known as can lights, can illuminate any room with focused task lighting or ambient glow. But determining the right number of can lights needed requires careful planning and calculation. Installing too many creates a cluttered ceiling, while too few can leave dark, shadowy corners in a room.
By factoring in room size, ceiling height, and the lighting goal, you can determine the ideal layout and quantity of can lights for a space. Follow some basic guidelines and formulas to ensure your room has ample lighting placed in all the right spots.
Determine the Room's Size
The first step in planning your lighting is to measure the physical dimensions of the room. Simply multiply the length by the width to calculate the room's total square footage. A larger space will generally require more light fixtures than a smaller one to sufficiently illuminate every nook and cranny.
As a baseline, here are some general recommendations for can light quantity based on room size:
- 100 sq ft room - 2-3 can lights
- 150 sq ft room - 3-4 can lights
- 200 sq ft room - 4-6 can lights
- 300 sq ft room - 6-9 can lights
However, square footage alone doesn't tell the whole story. The height of the room and the ceiling type will also impact the lighting plan, as discussed in the sections below.
Consider the Room's Function
In addition to physical size, consider how the room will be used when determining lighting needs. Is the goal bright, focused task lighting or gentle ambient fill? Recommended wattages and fixture quantities differ for kitchens, bathrooms, bedrooms, and living spaces based on their unique purposes.
For example, a bedroom may only require 3-4 recessed lights for soft, general illumination. But a kitchen likely needs ample task lighting over key workstations - plan for 8-12 can lights above the sink, stove, counters, and breakfast area. For bathrooms, place moisture-resistant can lights surrounding the shower and vanity for visibility.
Think about how the room will be furnished as well. Large pieces like beds and couches can block light distribution, so account for furniture layout when planning.
Desired Lighting Level and Style
Consider the desired lighting effect, mood, and function next. Do you want to highlight artwork with pinpoint accent lights? Provide widespread ambient glow for general illumination? Or direct bright task lighting to specific areas?
For accent lighting, install individual can lights over pieces to spotlight with narrow beam spreads. Ambient lighting calls for more numerous fixtures with wider beam angles dispersed evenly. For task lighting, concentrate higher output recessed lights over work areas.
The necessary light level, measured in lumens per square foot, varies by application as well:
- Ambient lighting - 3-5 lumens/sq ft
- Task lighting - 30-50 lumens/sq ft
- Accent lighting - 10-20 lumens/sq ft
Using the right bulb color or temperature also impacts the aesthetic. Cool white LEDs provide bright energizing light. While warm white LEDs or halogens make a space feel relaxed and inviting.
Calculate Light Spacing
Proper spacing between can lights prevents dark spots and uneven illumination. As a general rule, the distance between lights should be half the height of the ceiling. This lighting design rule applies to standard 8 foot ceiling heights.
For example, in a room with an 8 foot ceiling, space recessed lights 4 feet apart. This spacing guideline results in sufficient light overlap from adjacent fixtures' beams. But for higher 9 or 10 foot ceilings, extend the spacing to 4.5 or 5 feet respectively.
Viewing the ceiling layout on grid paper first, sketch circles using each light's beam diameter to visualize coverage. Adjust the spacing and quantity until all areas are overlapped.
Factor in Light Beam Spread
An important factor impacting coverage and spacing is the beam spread of the selected can lights. This refers to the angle at which the bulb emits light. Flood lights have the widest beam spreads, ranging from 120-150 degrees. Spot lights concentrate into narrower 30-60 degree beams. Standard PAR reflector lamps fall somewhere in the middle.
Wider beam lights can illuminate larger areas, meaning they can be spaced further apart. Narrow spot lights require closer spacing of 4 feet or less to avoid gaps in coverage.
Check each fixture's specifications to determine the beam spread. Use wider floods over open floor space, and narrower spots to concentrate light in specific zones.
Mind the Ceiling Joists
Another consideration when laying out can lights is locating the ceiling joists. These are the framing beams between the drywall or plaster. Recessed lights must be inserted precisely between the joists, or additional framing work will be required.
Joists generally run at 16 inches on center. So ideal recessed lighting spacing may be slightly adjusted to align with the joists. Consider their placement early when creating your lighting plan.
Using a stud finder on the ceiling can locate joists so you can plot lights accordingly. Just be sure to note joist direction, as they can change mid-run.
For Vaulted Ceilings
On ceilings with sloped or angled sections, traditional spacing guidelines may not apply. The varying mounting height impacts how far light will spread and overlap.
For accent lighting individual surfaces, install fixtures as high up the slope as possible. This maximizes the beam spread. For overall illumination, stagger lights across the incline, keeping beams trained downward.
Also consider utilizing ceiling or pendant mounted fixtures to supplement recessed lighting. These can be easily directed to light vaulted areas.
Consider Room Obstructions
The layout of a space will inform smart placement of recessed lighting. Note any architectural details, ceiling fans, vents or pipes that may obstruct overhead light distribution.
Also account for large furniture pieces like beds, bookcases, and cabinets. Illuminate fully around and even behind these fixtures for comprehensive lighting.
Strategically position can lights to avoid any light blockages. You may need to install additional fixtures to compensate for obstructions.
Choose Appropriate Housing
For installation in insulated ceilings, always choose insulation-contact or IC-rated can light housings. These are designed to be in direct contact with insulation without overheating.
In bathrooms or humid areas, specify airtight or AT housings on your cans. These prevent moist air from penetrating fixtures, avoiding hazards.
Picking the right housing type for the environment ensures recessed lights function safely and efficiently.
Create a Lighting Plan
With all the planning considerations covered, now sketch out your lighting layout on grid paper. This allows you to strategically place can lights with ideal spacing based on room dimensions and obstructions.
Map the joists, windows, doors, and large furniture pieces first. Then use your desired light spacing rules to plot can locations row by row. Adjust fixtures as needed until the layout eliminates dead zones.
Viewing the room's lighting zones mapped out two-dimensionally ensures proper illumination and coverage. Installing recessed lighting directly based on this plan will result in the ideal quantity and placement.
With smart planning considering room details like size, ceiling height, and furnishings, you can determine the perfect number and positioning of recessed lights. Follow lighting design fundamentals and rules of thumb to ensure ample illumination free of shadows.
While lighting formulas provide starting guidelines, also rely on creating a detailed lighting map. This allows you to customize the fixtures and spacing to fit your unique space. Get ready to install recessed lighting that makes any room shine bright.