How To Install A Skylight

Ever wondered why some skylights brighten a room for years with no leaks, while some become a headache? Installing a skylight can sound risky, but with the right tools and a clear plan, it’s simpler than you think. This guide walks you through each step, making it easy to bring natural light into your home without worry. Whether you’re new to DIY or just want to avoid common mistakes, follow along and see how a little preparation leads to a leak-free skylight that changes how your space feels.

Tools and Materials for Skylight Installation

Before cutting into your roof, gather every tool and material you need. You will need:

A circular saw
Utility knife
Hammer, drill
Tape measure
Chalk line

Safety equipment :

Gloves
Goggles
A sturdy ladder

For materials, prepare these because a high-quality underlayment prevents leaks.

The skylight kit
Roofing nails
Flashing
Roofing felt
Sealant

Make sure to pick a clear day to work because moisture can ruin the process. Also make sure to check local codes and obtain any permit before starting. Planning ensures smooth installation and avoids costly mistakes later.

Measure twice to prevent cutting errors. Mark all areas carefully with chalk. By prepping your tools and materials first, you set the stage for a leak-free, durable skylight that brightens your home.

8 Sure-Shot Steps for Installing a Skylight

Step 1: Mark and Cut the Skylight Opening

Start by picking the exact spot for your skylight, ideally between two roof rafters to avoid extra framing work. Use a tape measure to double-check your measurements, then outline the opening with chalk. Drill a starter hole inside your marked lines. From the roof, use a circular saw to carefully cut along the outline, working slowly to avoid splintering. Remove the shingles and roof sheathing inside the outline, keeping the cut edges clean, straight and square for a tight, proper fit.

Step 2: Prep and Waterproof the Opening

After cutting, inspect the opening for any rough spots and clean up the edges to ensure a perfect fit for the skylight. Next, add a waterproof membrane or roofing felt around the opening, slipping it under the roof shingles if needed. Press it down flat so it bonds with the roof surface and blocks out moisture. Take your time with this step, since a clean, sealed base is the first line of defense against leaks and future water damage.

Step 3: Place and Secure the Skylight

Carefully lower the skylight into the cutout opening, making sure the edges are flush with the roof. Use the brackets or flange included in your skylight kit to screw the frame securely to the roof deck. Tighten the fasteners, but don’t overtighten to avoid cracking the skylight or damaging the roof. Once in place, run a bead of roofing sealant under the flange or mounting hardware for added protection.

Step 4: Add A Flashing Base

Slide a layer of waterproof roofing felt or membrane under the skylight’s bottom and sides, pressing it tightly against the frame and roof. Overlap the layers so water always runs over, not under, the barriers. Use a roller or your hands to push out any air bubbles and smooth the material flat. Double-check that every edge is covered for complete protection against moisture intrusion, then get ready for the flashing.

Step 5: Install the Flashing Components

Start with the bottom (sill) flashing, sliding it under the skylight’s bottom edge and securing it with roofing nails. Next, install the side flashing pieces, overlapping each one as you move up the skylight’s sides. Finish by adding the top flashing, tucking it under the shingles above the skylight. Double-check that each layer overlaps correctly and lies flat. This layered system forces water to flow away from the roof and keeps your skylight leak-free.

Step 6: Seal All Edges for Leak Protection

Once the flashing is in place, use roofing sealant to create a watertight seal along every edge. Run a continuous bead of sealant along the seams where flashing meets the roof and skylight. Press down on the flashing gently to help the sealant bond. Make sure there are no gaps or open edges where water could sneak in. Go slowly and inspect every seam like it is your last line of defense against leaks and ensure your installation stands up to weather year after year.

With flashing and sealant set, replace the roof shingles around the skylight, tucking each shingle over the flashing’s exposed edges for complete coverage. Nail them down gently to avoid damaging the new flashing and membrane Pay extra attention to corners and edges. Shingles should sit flush and lock out water. If needed, trim shingles for a perfect fit. Double-check that all nail heads are covered by overlapping shingles and finish by brushing away debris to keep your new skylight area looking neat and professional.

Ensure the skylight sits flush with the roof. Use a garden hose to run water over the skylight, checking for any leaks or drips inside. If you see a problem, dry the area and reseal where needed. Once satisfied, clear away tools and leftover materials. Inspect the roof for loose nails or debris. Your new skylight is now ready to fill your space with natural light, brightening your home for years.

Even the best skylights installation needs upkeep. Check the flashing once a year, especially after heavy storms. Clear leaves and debris that trap moisture. It’s best recommended to wash the glass with mild soap to keep it clear. Check for condensation inside because it shows you need to change your seal. If caulking cracks, make sure to reseal it. Also keep gutters clear so water drains freely. Regular care keeps your skylight bright and leak-free for years.

Conclusion

A skylight changes how a room feels. Installing one may seem complex, but with these steps, you can do it with confidence. Let this blog remind you that good preparation, proper flashing and routine care make all the difference. If you ever feel unsure, call a pro to guarantee watertight results. When done right, your skylight will flood your space with light and add value to your home for many years to come.

Rooflights and Skylights UK is your trusted choice for high-quality skylight solutions across the UK. Whether you’re planning a new installation or upgrading an existing roof window, our team is here to help. You can contact us to discuss your project, or if you prefer, our skylights are designed for easy installation by a qualified tradesperson.