How to Install a Light Shaft on Roof for Natural Light

A light shaft on your roof can bring in a ton of natural light, making your home feel brighter and more welcoming. This is especially useful in areas with limited natural light.

To start, you'll need to determine the best location for your light shaft, which will depend on the layout of your home and the direction of the sun. Typically, this is facing north or south to minimize heat gain in warmer climates.

The size and shape of your light shaft will also impact its effectiveness, with larger shafts generally allowing more natural light to enter. For example, a 2x4 foot shaft can bring in about 1000-1500 lux of light.

A light shaft on your roof can be a beautiful feature, but it requires careful construction to ensure it's safe and functional.

The roof construction of a light shaft typically involves a combination of materials, including wood, metal, and glass.

The size of the light shaft will determine the type of materials used, with larger shafts requiring more robust materials to support the weight of the roof and the weight of any fixtures or furniture that may be placed within it.

Framing and drywalling the shaft requires some careful planning to get it right. To create a smooth transition from the roof slope to the vertical wall, I tapered the hole to open a little.

The wall below the top end of the skylight should be sloped so that it's perpendicular to the roof slope. This creates a clean and sturdy foundation for the skylight.

The short wall on the low end should be made vertical to provide a solid base. I made it vertical to ensure a secure attachment for the skylight.

The side walls should be made vertical up to a point, and then tapered out towards the bottom. I tapered them out by 1.5 inches on either side to create a smooth curve.

To avoid having to mud another drywall joint, you can score a deep line into the other side of the drywall and remove some gypsum from that score. This trick worked nicely for me and didn't require any special tools or techniques.

Curious to learn more? Check out: Dormer Wall

The vapour barrier should be installed next, followed by the drywall. Make sure to secure the drywall tightly to the framing to prevent any air leaks.

Once the drywall is in place, you can start to mud and sand it. Be prepared for a bit of dust in the air, but drywall dust is relatively easy to clean up compared to rock dust.

Building a skylight shaft in a truss roof can be tricky. Building codes prohibit modifying the webs and chords of engineered trusses in the field without an engineer’s approved design.

Leaving the trusses and any bracing intact is a good option. This way, the webs and chords remain exposed as they run through the opening.

Painting the trusses adds character to the opening. The trusses can become a design feature, rather than just a necessary part of the roof structure.

For a project, I installed a pair of skylights spaced one truss bay apart. This was 24 inches in this case, and the sides of the skylights angled to the adjacent trusses on each side.

Worth a look: Whats a Truss Roof

To save money on vaulted ceiling installations, consider using an Instant Light Shaft from VELUX. This product is specifically designed for 90° shafts and works on all "box" type light shafts, as long as they're not flared.

The standard depth of an Instant Light Shaft is 16 inches, which can be trimmed to fit actual on-site dimensions. All other pieces are pre-cut to size, making it easy to assemble on-site. If multiple skylights are installed, be sure to maintain a minimum spacing of 4 inches around all sides.

To lay out the opening before installing the skylights, poke holes through the ceiling to mark the inside edges of the trusses next to the bays where the skylights will go. This will help you determine the location of the skylights and make the installation process smoother.

Fall protection is crucial during skylight installation. Make sure to include underlayment, drip edge, flashing adjoining walls, dormer and skylight flashing, chimney flashing, vent flashing, and gutters in your preparations.

Recommended read: Ceiling Lights

Before installing skylights, it's essential to lay out the opening in the ceiling. This involves marking the inside edges of the trusses next to the skylight bays by poking holes through the ceiling.

To start, you'll need to decide how much of the existing flat ceiling you want to leave beyond the top and bottom walls of the splay. Snap chalklines through the holes to locate the sides of the skylight's splayed opening.

Next, complete the layout for the opening by snapping chalklines and drilling a hole through the ceiling at each corner to transfer its position to the attic. This will help you determine the location of the skylights.

To contain the mess, do as much dirty attic work as possible before opening the ceiling. This includes removing insulation, installing skylights, and giving the exposed trusses a quick coat of primer.

To minimize dust and debris, cover the floor and walls of the room with sheet plastic.

Velux FS Skylights are a great option for replacing existing deck-mounted skylights or installing new ones on roofs with an average to steep pitch.

They come in fourteen different sizes, so you're sure to find one that fits your needs.

The daylight area of FS skylights ranges from 2.8 to 12.4 square feet, giving you plenty of natural light to brighten up your space.