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Skylight Installation: A Step By Step Guide For Homeowners

August 9th, 2021 BY First American Roofing

How cool would it be to install a new skylight in your home? You get more natural light, some more fresh air, and they just look cool. Skylight installation might sound complicated, but a little hard work it can be done in a few steps (or sooner with the help of a professional). Regardless, we’re going to give you a step-by-step guide on how to install a skylight on your roof in just one day.

Before You Start

We know starting a DIY project can be exciting, but before you start cutting holes in your roof make sure you understand the cost, tools, and work involved.

What You’ll Need to Install Your Skylight

Before you buy all of the tools the pros use for a professional installation, we have put together a list of the necessities that will get you through this project without breaking the bank.

man installing a skylight into a roof

Cost of adding a skylight

The total cost of adding a skylight can range quite a bit depending on the type, brand, and installation method of your skylight (DIY vs pro).

A basic skylight will start around $150 and increases based on size and features. Of course there are also premium options like Velux skylights which start around $600 each. Granted, they offer a wide variety of models ranging from the basic skylights to solar skylights that remotely open and close. Once you have your skylight selected, you need to get the proper flashing or flashing kit which typically run anywhere from $100 to $400. Once you factor in the cost of various tools, shingles, and other material costs, you should expect the total cost to start from $400 and go up form there.

If you would prefer to go the professional route, installation costs can generally range between $500 and $3,000 depending on the project. Doing it yourself is a great way to save money, but it can be time consuming if you have never done it before. Regardless which method you pick, let’s break down the steps to installing a skylight to your home.

STEP 1: CUT THE ROOF OPENING

The first step will, of course, be to cut the opening to install your skylight. First, you’ll want to ensure you’ve got good weather for the day. The last thing you want to happen is for rain or wind to ruin this step.

Then determine where you want your skylight and what size you want it to be. Start from inside and mark out the dimensions of the skylight. Make sure the skylight is located between joists (if possible) and the proper header joists are added to ensure proper support of the window.

If you are planning to instal a large skylight and need to cut multiple roof rafters, make sure to call a professional as this could compromise the structural integrity of your roof or new skylight.

Once you have everything marked out drill four long deck screws through where each corner will be. Those screws will indicate on the exterior roof where to begin.

Then you will need to get on the roof to remove all the shingles at least 6 inches past each of those screw markers. Once the shingles are removed, mark four straight chalk lines as a guide to using the circular saw to cut out the rectangle shape in the roof.

man cutting an opening in a roof for skylight

STEP 2: INSTALL THE FLASHING

Next, install your flashing along the entire window sill. This creates the first barrier to prevent leaks. For proper installation, make sure to apply the self-adhesive flashing on each side, then cut to fold over the edge enough to create a barrier the width of the skylight sill. Nail the sheathing down on all sides using your roofing nailer.

roofing professional attaching flashing for skylight installation

STEP 3: PLACE THE SKYLIGHT

Once the sill has flashing securely installed, carefully get your skylight to the roof with the help of a friend or pully system. Place it in the cut-out gently in place. The skylight should have a flange edge where you can place your 1.25-inch roofing nails every few inches to secure it in place.

roofer placing skylight during installation

STEP 4: SEAL THE EDGES

Time for more sealing. Cut your self-adhesive membrane to stick to the skylight’s flange and extend past its edge a few inches. This creates a watertight seal around every edge of your skylight. You will need to do this on every side to create another barrier against leaks before you install your sill and step flashing.

roofer attaching seal and flashing for skylight installation

STEP 5: INSTALL SILL FLASHING

Your skylight came with a u-shaped piece of flashing to place on the bottom sill. This should easily slide in place, and you can secure every side using your roofing nailer. Then, the final step will be to install your shingles back in place, covering that sill flashing. Note, this is only installed on the bottom of your skylight window.

STEP 6: INSTALL STEP FLASHING

Next, each side requires step flashing to be installed. This installation will go in steps, from the bottom up. Place your first l-shaped step flashing piece near the bottom of the skylight. Nail it in place and then cover it with a shingle. Then, install your next step flashing overlapping that shingle by a few inches, secure it in place, and put your next shingle in its proper place. Continue these steps on both sides until you reach the top corners.

roofer attaching saddle flashing for skylight installation

STEP 7: COUNTERFLASHING

The counterflashing will simply click into place over where you installed your step flashing on each side. This is a key step to ensuring snow and rain don’t blow under the edge of your skylight.

STEP 8: SADDLE FLASHING

The saddle flashing is similar to the sill flashing, but it goes on the top. You will simply slide it under the shingles above your skylight and slide it in place on top. Secure it with roofing nails and re-install your shingles over the saddle flashing as you’ve done thus far, and it should be good to go.

roofer working with flashing during skylight installation

STEP 9: ENJOY!

With all of the flashing, shingles, and skylight in place, safely make your way back down off the roof and head inside. You can double-check that everything looks good from the inside, and if you have a skylight that opens, you can test that and make sure everything is in working order. Once everything is good to go, you can get started on cleaning up the interior ceiling.

finished skylight installation

These steps we’ve laid out are relatively simple but do require a certain amount of expertise. We always recommend hiring a professional when you are doing anything that requires getting up on the roof and making drastic home improvements like cutting the opening in the roof. One slip from an inexperienced homeowner can cause injury, accidents, or damage to your home. Luckily, First American Roofing offers both skylight and sun tunnel installation, so you don’t have to worry about a thing! Contact us today for a free estimate on your project.