Why You Can Trust Skylights

The most effective way to improve the atmosphere and indoor ambiance of your home is also the way that’s most likely to cause fear and hesitation. And the crazy thing is, the realities behind this fear and hesitation are more than 30 years out of date.

Skylights are my single favourite feature to see upgraded in home renovations, and the best can add beautiful light and plenty of fresh air to most rooms. So why aren’t there more skylights in Canadian homes?

The problem is that many people still don’t trust them to keep rain out. Not complete trust, anyway. Everyone’s heard stories about someone, somewhere, who installed a skylight in 1972, and how perennial leaking has happened ever since. And while these stories may have a basis in a 40-year-old reality, it’s important not to deny yourself the joy of light and air today just because of something that hasn’t been true for decades.

Yes, some brands of cheap skylights leaked years ago. Yes, some cheap brands of skylights might even leak today. But the fact is, you can bet your life that decent, modern skylights won’t leak. At least not any more often than the rest of a good roof. Trouble is few people ever see why first-hand.

Modern Skylights: Leak-Free By Design

I was reminded of all this as I installed a set of four. Standing on a 2×10 plank, 15 feet off the ground on a roof sloped 45º, tied to a neighbouring oak tree in my climbing harness, I realized why tales of bad skylight experiences persist. Besides the human tendency to remember horror stories, it’s also simply a matter of physical accessibility. Climbing roofs is dangerous and scary. Few homeowners have ever seen a modern skylight installed, so few appreciate the reliable designs at work.

Attitudes would be entirely different if more people could see how proper skylight flashing goes down; interwoven with neighbouring roof shingles over top of a self-sticking, waterproof barrier. Everything is kept secure and dry without resorting to caulking or roofing tar or anything else that’s destined to fail over time. In fact, in the case of the Velux skylights I was installing most recently, there are actually three layers of security at work all at once, even when one layer alone would do the job.

Today’s Best Skylights: 3 Layers of Rain Protection

Villum Kann Rasmussen, founder of Velux,  invented skylights in 1941, and their no-leak line of skylights is an attempt to assure homeowners right from the start that these things are reliably dry. Only time will tell how effectively this PR campaign will be at dispelling old fears. As someone who has installed different brands of skylights over the last 15 years, I know I’ve never seen anything that exceeds Velux quality. And that goes for both day-to-day function and those hidden design features that keep water out.

Layer 1: Waterproof Metal Flange

Velux Pivotting Roof Windon Skylight

The skylights I’ve been working with include a continuous, waterproof metal flange around the perimeter, with a foam gasket on the bottom that seals to the roof deck. This alone won’t keep water out, but it’s an excellent start. It also helps the skylight span small irregularities on the wooden roof deck as it’s fastened with roofing nails.

Layer 2: Self-Sticking Membrane

The second layer of waterproofing comes next. It’s more substantial than the first and involves a self-sticking membrane that overlaps the roof underlay that surrounds the skylight, before wrapping upwards on all four flanged sides of the skylight. This membrane creates a sealed, raised synthetic barrier that’s capable of keeping water out on its own.

Layer 3: Aluminum Step Flashing

The final layer in the Velux system is the most impressive of all. It involves pieces of aluminum step flashing that go down on the roof and over top of the sticky membrane. Each piece of flashing is overlapped by shingles as they’re installed, harnessing the power of gravity to keep water flowing downwards, out of your house and leak-free. The step flashing works with preformed aluminum head and base flashing on the top and bottom of the skylight keeping water running down from above.

Let In Light and Fresh Air

Most people think about skylights as a way of adding light, but it’s amazing what openable skylights can do for whole-house ventilation, too. Install a few in the highest and hottest parts of your house and it can let you reduce air conditioning use big-time during the kind of hot summers that are becoming so common.

Fear thrives best in an environment of ignorance, and skylights are a case in point. While tired stories about old designs continue to rob people of exceptionally bright, fresh and healthy indoor spaces, it’s rare that anyone sees the impressive technicalities behind today’s best installations. While there’s more involved in your decision about skylights than just reliability, rest assured that fear of leaks does not have to be on your list of concerns.

Posted on January 16th, 2013

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