This past winter we got hit with wind gusts up to 80 mph, the wind was strong enough it broke a neighbor's glass patio table. I inspected my system and didn't note any changes but it got me thinking about my wind uplift design loads. So I took a closer look at everything and not that content with the numbers I'm seeing.
My system as installed: https://imgur.com/gallery/aDSbsJC
More details below on my system and roof after my questions if anything is confusing.
I'm considering adding SnapNrack Metal Roof Bases to the ends of my arrays in addition to my S-5-N standing seam clamps. I'd likely have to get in the attic and block the trusses for every mount using a 4"x4" but it seems feasible.
MY QUESTIONS
1. Does anyone have any advise on products I should consider?
2. Do you think mixing mounting types would cause any problems?
3. Can I add these additional mounts down the same trusses or should I attempt to stagger them knowing the center truss will likely be blocked for both.
4. On the metal roof panel is it better to be closer to each panels nail strip?
5. Does anyone ever put additional boots over the mounts for waterproofing/water diversion?
Thank you for any help and advise,
DETAILS ON MY SYSTEM
I thought I was doing everything right in my solar install. I DIY'd and used a local DIY company from which I bought a stamped engineer letter and a set of plans for my 38 module SolarEdge install. I have a concealed nailstrip 29 guage 16" standing seam metal roof which I used S-5-N clamps with SnapnRack rails. The 16" metal roof is secured every 17" with wood screws through 7/16" OSB. I have 2 roofs both are east and west facing: SOUTH - gabled roof with scissor truss built with 2"x6" with 16 modules on the east and 16 modules on the west and NORTH - gabled roof with common trusses built with 2"x4" with 6 modules on the east. Both roofs are about 27 degrees and modules are flush mounted about 5" high. All modules are 4' or more up from the eve. The modules on the West roof are all 3' from the roof's rake and ridge. The North Roof on the east has an array 18" from the ridge and 18" from the rake and the South roof on the east has an array 18" from the rack (4' drop to north roof). The local company and AHJ had said was fine and approved. My house is on a hillside and the West slope is wind exposure C with the East slope exposure B and a roof height of around 30-35 ft high. The plans I bought called for clamps on every 3 seam (48"); I upped the frequency to every other seam during installation trying to be conservative and because it just made sense. So as installed:
6 clamps per 162" rail; 12 clamps per row; 5 clamps per 122" rail; 10 clamps per row; 3 clamps per 81" rail; 5 clamps per row
My rough numbers are uplift looking into uplift forces are 20 lbs/sq ft seems like a reasonable design number. If so a row of 4 modules is about 1,400 lbs of uplift or an array of 2 rows of 4 modules is about 2,800 lbs. Mass of 8 panels 350 lbs so 2450 lbs uplift to resit. OSB has a pull out strength of 173 lbs/in with #10 wood screws so 75 lbs per screw. If you assume every clamp will distribute to at least 2 screws then the 8 modules has 48 screws or 75 lbs*48= 3,600 lbs of resistance. This should be about a 1.5 safety factor but it doesn't make me that happy and I'd like to reinforce the system.
At the start of the project I was worried about putting holes in my metal roof worrying about leaks, I didn't see how I would manage to connect to the trusses, and S-5 clamps seemed so elegant and simple. Now I'm more worried about he West arrays popping off the roof. After reading posts I should have used a clamp on every seam. I have added some S-5 clamps to the seam of the top and bottom rails of my arrays as it wasn't hard to retrofit. However, the middle rails are a very difficult to access. This is why I'm considering adding the Metal Roof bases at the end of the arrarys. Using 4'x4' blocks horizontally connecting trusses with 5/16" lags has a pullout of 300 lbs/in so 300*3.5" = 1,050 lbs per lag. 8 lag bolts is then 8,400 lbs of uplift. Those are some over design safety factor numbers I like better.
My system as installed: https://imgur.com/gallery/aDSbsJC
More details below on my system and roof after my questions if anything is confusing.
I'm considering adding SnapNrack Metal Roof Bases to the ends of my arrays in addition to my S-5-N standing seam clamps. I'd likely have to get in the attic and block the trusses for every mount using a 4"x4" but it seems feasible.
MY QUESTIONS
1. Does anyone have any advise on products I should consider?
2. Do you think mixing mounting types would cause any problems?
3. Can I add these additional mounts down the same trusses or should I attempt to stagger them knowing the center truss will likely be blocked for both.
4. On the metal roof panel is it better to be closer to each panels nail strip?
5. Does anyone ever put additional boots over the mounts for waterproofing/water diversion?
Thank you for any help and advise,
DETAILS ON MY SYSTEM
I thought I was doing everything right in my solar install. I DIY'd and used a local DIY company from which I bought a stamped engineer letter and a set of plans for my 38 module SolarEdge install. I have a concealed nailstrip 29 guage 16" standing seam metal roof which I used S-5-N clamps with SnapnRack rails. The 16" metal roof is secured every 17" with wood screws through 7/16" OSB. I have 2 roofs both are east and west facing: SOUTH - gabled roof with scissor truss built with 2"x6" with 16 modules on the east and 16 modules on the west and NORTH - gabled roof with common trusses built with 2"x4" with 6 modules on the east. Both roofs are about 27 degrees and modules are flush mounted about 5" high. All modules are 4' or more up from the eve. The modules on the West roof are all 3' from the roof's rake and ridge. The North Roof on the east has an array 18" from the ridge and 18" from the rake and the South roof on the east has an array 18" from the rack (4' drop to north roof). The local company and AHJ had said was fine and approved. My house is on a hillside and the West slope is wind exposure C with the East slope exposure B and a roof height of around 30-35 ft high. The plans I bought called for clamps on every 3 seam (48"); I upped the frequency to every other seam during installation trying to be conservative and because it just made sense. So as installed:
6 clamps per 162" rail; 12 clamps per row; 5 clamps per 122" rail; 10 clamps per row; 3 clamps per 81" rail; 5 clamps per row
My rough numbers are uplift looking into uplift forces are 20 lbs/sq ft seems like a reasonable design number. If so a row of 4 modules is about 1,400 lbs of uplift or an array of 2 rows of 4 modules is about 2,800 lbs. Mass of 8 panels 350 lbs so 2450 lbs uplift to resit. OSB has a pull out strength of 173 lbs/in with #10 wood screws so 75 lbs per screw. If you assume every clamp will distribute to at least 2 screws then the 8 modules has 48 screws or 75 lbs*48= 3,600 lbs of resistance. This should be about a 1.5 safety factor but it doesn't make me that happy and I'd like to reinforce the system.
At the start of the project I was worried about putting holes in my metal roof worrying about leaks, I didn't see how I would manage to connect to the trusses, and S-5 clamps seemed so elegant and simple. Now I'm more worried about he West arrays popping off the roof. After reading posts I should have used a clamp on every seam. I have added some S-5 clamps to the seam of the top and bottom rails of my arrays as it wasn't hard to retrofit. However, the middle rails are a very difficult to access. This is why I'm considering adding the Metal Roof bases at the end of the arrarys. Using 4'x4' blocks horizontally connecting trusses with 5/16" lags has a pullout of 300 lbs/in so 300*3.5" = 1,050 lbs per lag. 8 lag bolts is then 8,400 lbs of uplift. Those are some over design safety factor numbers I like better.
Comment