How to Install a Skylight: Tips and Procedures

You’ve heard of skylights and their benefits, and now you want one for your home.

The advantages of installing a skylight, such as improving aesthetics, ventilation, and lighting, are enough to make one feel it’s a worthy installation for their home.


SkyLight installation ideas


And when you consider that skylights can improve the resale value of your house too you can see they are a worthy investment.

Although experts recommend we hire a professional for a skylight installation project, you can also put it up yourself.

If you decide to, here are the steps to follow.


  1. Choose a skylight

Do you want the skylight only for lighting purposes, or do you require ventilation too? There is a skylight to suit every purpose. But generally, there are two types of skylights. These are;

  • Fixed skylights

These skylights do not open. They remain shut and only let in sunlight. You can use them to improve ambiance and let in additional light into an area.

Any rooms that require extra light, such as attics, kitchens, and living rooms, will benefit from a fixed skylight.

Use them to create extra living or working spaces by turning dark rooms such as attics into useful spaces like a bedroom or office.

You may also install a fixed skylight in bathrooms and other wet areas such as indoor pools, where their light can prevent mold and fungus growth.

  • Venting skylights

Venting skylights are natural light installations that you can open and shut depending on your needs. They will not only let natural light into your home but also increase aeration.

Venting skylights are an excellent way to reduce heat or increase warmth in the house.

If it’s too hot, simply open your skylight and let the warm air out. And when it’s too cold, shut it and let the sunlight stream through the glazing and heat up your house.

Once you pick a skylight, the next step to take is to choose a suitable location for it.


  1. Picking a location for your skylight

You cannot just place a skylight anywhere on your roof. The location of your skylight will determine how it functions and its benefits to you. For example, southward-facing skylights access lots of direct sunlight and heat.

The room over which you need a skylight will also determine its placement on the roof and the type of skylight you install.

Some installations will require you to locate a skylight over a room below an attic. That will require the construction of a shaft to direct the light into the intended space.

If you choose this type of installation, you must select an area where no wiring or plumbing passes through; otherwise, it will obstruct your installation.

Keep in mind that the location of your skylight will determine how much sunlight and warmth you get in your home.

If you install a skylight that gets lots of sun, you should consider how to manage heat gain to reduce cooling costs. Some solutions are skylight shades or blinds.


  1. Pick the right skylight size

Once you decide where to install your skylight, it’s time to choose the right one for the job.

Most people prefer large skylights, but that leads to increased costs of installation. However, they provide better lighting and ventilation.

Ideally, a skylight should measure 5 percent of a room’s floor size if it has many windows and 15 percent where there are few windows.

Your roof type also matters. If you have a truss roof, you must measure the space between rafters and find a skylight that fits that space.

Truss framed roofs can accommodate a 22.5-inch wide skylight because the framing between trusses measures 24 inches at the center.  But customized skylights for truss roofs can measure up to 4 feet wide.

However, if you have a stick roof,  you may pick a larger skylight measuring between 33-49 inches.

If you are stuck on size, your area building codes may help you choose a skylight that your roof can hold and one that will withstand the weather in your area.  Check them out when looking for the correct skylight size.

The slope of your roof will also determine how you mount your skylight. You may curb or deck mount it.

Curb-mounted skylights come fully assembled and sit on top of a frame. They are ideal for flat or low-pitched roofs.

Deck-mounted skylights lie flush against the roof and are easier to customize into different shapes and sizes. They are best for pitched roofs.


  1. Install the skylight

Now that you have chosen the right skylight for your home, it’s time to install it. You require tools such as a utility knife, saw, tin snips, hammer, roofing nails, and a prybar.

These materials will help you to cut into the roof and install the structural framing. They will also help you to fix the skylight over the ceiling.

Additional materials you should include are drywall, paint, and 2 by 4s or 2 by 6s for the framing.

  • How to install a skylight with a light shaft

If you must locate your skylight over a room underneath an attic, you need a light shaft. That will require 2 by 4s for the frame, flashing materials, and drywall for its interior.

Start by marking the space over which you need to install the skylight from inside. You only need to mark the area with a pencil or something visible.

Then, take time to find out if any installations such as vents, electrical wires, or plumbing lines run between this spot and the roof. If there are, you must re-route them. That will necessitate the services of a plumber and electrician.

If the space is empty, you can start installing your light shaft.

Start by cutting through your ceiling from inside. Remove any drywall or insulation you encounter on your way to the roof. Then shift to the roof and mark the space for your skylight. It should look like a square or rectangle.

Next, drive screws into each corner of the space and remove shingles from the section in between them.  Once you strip the shingles,  mark the size of the skylight using chalk. It should look like a rectangle or square.

You can then cut into three sides of the outline using a circular saw. Lastly, have someone hold the cutout from below while you cut into the fourth side to ensure it does not fall through your ceiling.

Now you have space for a light shaft,  and you can fix your skylight.


Curb-mounting your skylight

Is your skylight curb mounted? In that case, you need to secure it to the edges of the light shaft opening  from the top with four, 2 by 6s. These will create the curb over which you set your skylight.

Nail these four 2x6s together in the shape of your intended skylight, ensuring they are correctly measured to fit the opening.

You will come up with a box frame that you must secure over the roof opening by toenailing. That means you need to drive the nails in using an angle that will connect the frame to the roof.

Next, lower your skylight over the curb sills and nail sill flashing to the sides of the curb. Once you are done, replace the shingles over the edge of the curb sill and add some more to cover any exposed edges of the sill flashing.

You can then move forward by adding step flashing to the sides, and overlapping the shingles you’ve used to cover the sill flashing over them. Continue overlapping the shingles and step flashing all round until you properly secure the skylight.

Once you’ve finished step flashing, cover the area with head flashing on all four sides to prevent wind-blown snow or rain from damaging your skylight.

Lastly, cover the step flashing with saddle flashing by nailing it beneath the layer of shingles around your skylight. Ensure you cover the saddle flashing with more shingles leaving only 10 cms exposed. Your skylight is now in place.


Deck mounting your skylight

If your skylight is deck-mounted, it will likely have a frame with sheathing you can fit beneath your skylight to prevent water infiltration. Nail this sheathing down around the opening of the light shaft using roofing nails.

You can then attach self-adhesive weatherproofing along the bottom of the opening, ensuring you fold one inch of it over the edge into the roof opening.

Next, lower your skylight over the roof, starting with the bottom edge first and slowly lay it onto the rest of the opening. You can then drive screws into the skylight frame to secure it in place over the roof.

Once the skylight is secure over the roof opening, seal the area all around the skylight using roofing felt paper for underlayment. You may also add a silicone sealant membrane over it to add another layer of protection that will prevent leaks.

Next, nail the roof shingles you removed back over the sealed area and follow that with U-shaped sill flashing that extends to the bottom of the skylight.

You must further secure the skylight using step flashing, continuous flashing, and head flashing to prevent leaks, following the directions you used with curb mounting. That will complete your installation.


How do you install the light shaft?

You’ve now set up your curb mounted, or deck mounted skylight. It’s time to finish the light shaft. That is the hole you cut leading straight through to the room under the attic.

Since you already have holes cut on both sides, start by cutting 2x4s for the light shaft frame. These pieces of wood should fit between the skylight and ceiling to form a tight tunnel. Also, add some beams measuring 16 inches to act as drywall studs.

Next, nail insulation around the outside of the light shaft and cover the inside of it with drywall. Once finished, you can paint the interior the same color as your ceiling.


Installing a skylight directly over a room

You may only require to install a skylight directly over the room that requires lighting. That will not require a light shaft. You only have to cut into the roof and install the skylight over the room.

Start by measuring and outlining the space over which you need the skylight. You can then strip the shingles 7 inches beyond that space.

Using a circular saw, cut through the sheaths to create a space for the skylight. You may ask someone to lower the cut-off roof section for you.

Next, underlay the bottom edge of the cut opening using weatherproof roofing paper. Then, lower the skylight unit over the opening and secure its flanges into the roof using galvanized roofing nails.

Once the skylight is secured to the roof, seal the area 6 inches around it with more weatherproof roofing paper. You should extend the paper to cover the skylight frame, the flanges, and any area 6 inches past the skylight.

Now you can nail shingles over the flanges, ensuring you cover the nails used to seal the area around it. Once you’ve covered the flanges, install U-shaped sill flashing on top of them, ensuring you cover the bottom end of the skylight and any exposed skylight sides with shingles.

You can then cover the shingles that have sill flashing with step flashing and follow that up with shingles too. Lastly, counter flash the step flashing all around the rim of the skylight.

To finish the job, install the saddle flashing securing it against the skylight with nails at the corners. You can then cover the saddle flashing with more shingles, only leaving four inches of it exposed to complete the installation.



That’s how to install a curb mounted, and deck mounted skylight over a room beneath an attic using a light shaft. We also give you tips on how to install a skylight directly on to a room without a light shaft.

Note that, while skylights are easy to install, doing it requires you to cut into your roof, which may cause unnecessary damage. If your skylight is too large, it’s best to hire a professional who will help you to lower, position and secure it onto a roof.

It’s maybe better to hire a roofing expert for the installation to preserve the integrity of your roof and ensure you do not void your product or roofing warranty due to a wrongful installation.

Remember to get a permit for your skylight installation and follow the necessary building codes. Also, ensure the skylight you choose comes with an installation and product warranty to ensure it lasts for a long time.



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