Another in my "curiosity" series of questions for those who are more experienced. Does anyone have a sense of how much rain, if any, makes it to the underlay during a typical storm event? In looking at the roof, it looks like everything channels down to the gutter, but I don't really have any visibility into what's under the tiles in that gap. Tempted to stick a remote camera ih through the vent, but figure someone already may have done that, or know the answer without resorting to that. Does all the rain stay topside? Does it flow staright down the glass and/or in the channels where the tiles meet? Does any significant portion hit the underlay? I know some will during backups, ice dams, snow, etc., but curious as to the design. As always, thanks for any thoughts.
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Rain and the Solar Roof
- Thread starter dhquigley
- Start date
Rainwater definitely gets below glass tiles. Most water flows down the glass tiles, but some small amount gets below the tiles. The system is designed to support this with vent/drains all along the bottom edging. Interesting question about ice buildup. It snows one day every 20 years hear, so no experience with it. The system was designed and tested in Buffalo, NY, so you would think snow and ice would have been design considerations.
It's something I've wondered, but I have not done anything to try and figure out myself. It doesn't seem like it would be too much - at least the amount of water I can see pouring off the roof into the gutters seems to be as high as I used to see (if anything, I think the roof + gutter replacement seems to catch more water than what I had in terms of downspout outflow - don't know what that means was happening before.) In any case, I expect (and do assume they tested to be sure) it should not be enough to cause any significant issues with ice buildup, but since you are in an area that is just a bit cooler than me, you will probably discover any problems first, so let me know.
I am not sure how much water will actually get under the tiles. Here is a link to an album of some videos I made with the rain on the tiles. This was made just after it rained and there was very little water draining under the tiles down to the vented edge by the gutter. This is even though the top row+ of the tiles were not yet installed.
Thanks very much for posting. Good to know I'm not the only one thinking about these things. These are fascinating. I am struck by a few things. First, how quickly water beads down. Second, how little seems to go between the tiles. I was convinced the gap between tiles would convey a lot more water. I saw a few beads in the last video, but not nearly as much as I expected. Third, I am glad you posted the video looking back up so we can see the window. For a minute, I thought you were walking around on wet Firestone, which we all know would not be ideal. Thanks again. Really helpful.
It has been reported here by a V2 or V3 owner that '90% of the rain flows above the tiles and less than 10% flows underneath the tiles'. That was after the owner asked the Tesla installer what they thought. The product has been designed to leak or allow the water underneath and force the underlayment to make the whole system waterproof. Therefore the roof is kept watertight by the underlayment. The underlayment was not designed or rated for that purpose. So the system is listed at UL as SR60T1 and must conform to agreements with UL and others. UL requires their family of products to list their characteristics and specs. The Firestone underlayment was designed to be installed as 1 layer and resist the elements for 120 days, not 25 years. There are also drains on the bottom of the eve flashings and the panels system has not been designed to be waterproof as every over roofing product has. For decades houses were kept waterproof with only a single layer of tar paper on valleys and eves with the rest of the decking only covered with 3tab shingles.
The major issue with this is the fasteners are normal roofing nails fired from a conventional shingle nailer. V1 had a wood framed base that is above the underlayment. When the elements (air, wind,water,uv) are exposed to the metal fastener it will rust and the wood frame will rot or stuff will grow on it.
Here is the best source of V3 info I've ever found it even includes the formerly secret Tesla V3 manual. Note the safety stuff and how they specify to install the 2 layers of Firestone.
https://www.arlingtonma.gov/home/showdocument?id=52776
The major issue with this is the fasteners are normal roofing nails fired from a conventional shingle nailer. V1 had a wood framed base that is above the underlayment. When the elements (air, wind,water,uv) are exposed to the metal fastener it will rust and the wood frame will rot or stuff will grow on it.
Here is the best source of V3 info I've ever found it even includes the formerly secret Tesla V3 manual. Note the safety stuff and how they specify to install the 2 layers of Firestone.
https://www.arlingtonma.gov/home/showdocument?id=52776
to close the loop on this, I had to talk with my installers today (changed internet router in the house and they need to update the equipment), so I asked about the intent of the system in this regard. He said, in line with others above, 85-90% will sheet off the glass with 10-15% hitting the underlay. They rely on the underlay to be water proof. Said it is akin to a concrete/metal roof in that regard. Still seems like unnecessary stress on the underlay, but there you have it.
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