Waterproofing solar projects on tile rooftops

In this special edition of Contractor’s Cornermounting manufacturer K2 Systems dispels the myth of “flashing-free” solar rooftop mounts and covers the latest in installing solar on tile roofs. K2 Systems is a global mounting provider, and Johan Alfsen, senior director of training, talks through the company’s latest innovation in flashing technology — butyl.

Below is a portion of the company’s Solar Spotlight podcast with Solar Power World, but be sure to listen to the full episode here or on your favorite podcast app.

What’s required to waterproof tile roofs?

There’s actually a little bit of confusion on this question and answer because different jurisdictions have different requirements based on what’s called, I’d say, “best practices” listed by organizations like the Tile Roofing Institute. The reason why I say it’s kind of confusing is because not all AHJs will mandate this. They’re OK with just sealant over bolts, which is the bare minimum. But some installers take it upon themselves to do it the most thorough way, or doing what’s called three coursing with roofing cement, where they tar in around a metal flashing to flash that in at the underlayment level and they add a layer of mesh and another layer of tar. So, it’s extremely time-consuming, and I can understand why some installers don’t want to do it or are begging for better ways, but not all jurisdictions mandate this.

How is installation on tile roofs different than others like comp shingle?

Tile roofs are a little more complicated because they have two waterproofing systems of the roof. Technically, comp shingle roofs have underlayment as well underneath the asphalt shingles, but you’re not coming anywhere near it. You’re penetrating through it, but you’re not reinforcing that waterproofing, it’s just another layer under the singles. While with tiles, there’s a big gap between the felt paper underlayment and the tile. So, the heart of a tile roofing system is at the underlayment level, whereas on comp shingle, as long as you waterproof on the surface level, you’re good to go. But tile has a little bit more complexity to it because it has the underlayment that is a little more fragile but also a very important part of the roof, and then you have the top tile level as well.

What are “flash-less” roof attachments?

the word “flash-less” is actually the wrong word to use that the industry is adopting with these flash-less products. What they’re referring to is these comp shingle roof mounting systems — for example, our Splice Foot — it’s a product that doesn’t have a metal flashing, it has a butyl flashing. And the reason why I say flash-less is the wrong term to use is because these products do have a flashing but they’re in a different form. Some of them call it a flexible flashing, some call it a pad flashing. It just depends on the product.

What is the benefit of using butyl vs. metal flashes?

In the case of comp shingle, a metal flashing is designed to be slipped between the shingle coursing, and in some cases where the shingles are so hot or so baked down, like in really hot climates like Las Vegas or Arizona where it gets over 100 °F and the roof just gets so cooked that you can’t pry a metal flashing between the shingles and you end up tearing up the shingles and causing more harm than good.

A flexible flashing or butyl flashing ends up being a better solution because you can stick it right down on top and it self-seals itself as you drive the screws through the butyl. It’s just an easier install, and it’s obviously regionally based, or installer based, with what they prefer. It has a lot of benefits and we do some videos as a comparison between metal flashings and non-metal flashings.

What products does K2 offer for tile mounting?

we always had tile hooks, we have all kinds of different tile hooks series for the different types of tiles, like flat tile or “S” tile or “W” tile. But we recently incorporated the same butyl that’s a part of our Splice Foot. We call that seal the EverSeal. That means the product has been tested thoroughly for water intrusion, wind-driven rain, submersion tests and heat and thaw. It’s getting put onto our tile hook series, so now we’re having tile hooks with butyl and what is going to provide is a much easier solution for installers who do want to seal the penetrations into the tile roof into the underlayment, and not want to bring up big buckets of tar and do the three coursing. They can use the butyl that self-seals into the roof. Our new hooks will be available with butyl as a part of the EverSeal series.

This podcast is sponsored by K2 Systems

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