The ideal deck mounted skylight, to prevent leaking, would have a flange that extended down from the roof ridge and to each side eve! That not being practical or possible, installers need to use special techniques and materials to prevent water from getting under the top and sides of the frame. Gravity usually prevents water intrusion at the bottom.
Different skylight manufacturers have various design ideas to prevent water from getting through the actual skylight. They also have suggestions on how to prevent water from intruding under the top and sides. Some methods are easier than others.
SIG Skylights Makes the Flashing Job Easy
At SIG Skylights, we make the flashing job as foolproof and easy as possible. Our frames are made with a heavy aluminum extrusion that is welded at the corners – thus resulting in a solid metal skylight frame. We designed the shape of the extrusion to use the largest extrusion die available. This way we have a solid metal 4 5/8” flange.
To “extend” the flange further, we want the installers to use a self-sealing, pliable membrane around the hole, then up the sides and then across the top of the skylight. The “gooey” side of these materials adhere to the side and top flanges and help extend them further out from the opening in the roof and seal against water intrusion. For roof pitches of 4:12 and greater you can use 18” width material. We recommend using it full width, 36”, on lower sloped roofs. You can download our installation instructions or watch an installation video on our website.
For contractors who do not need to buy an entire roll of self-sealing membrane, we have Grace Ice and Water Shield® available for purchase by the foot. We also sell it by the roll. It is a very sticky product that has nail gripping properties and is good for installation down to 40ºF.
The added cost of the proper material is much less expensive than dealing with a customer that has a leaking skylight!