Racking Question - Metal Roof

[seanheinle]

I had a metal roof installed on my house and now I'm pulling my hair out trying to figure out my racking options. The previous roof on my house was shingle. The metal roof was installed by nailing 1" purlins (furring strips) horizontally 24" apart directly on top of the shingles. The metal roof is then screwed to the purlins. The purlins do not line up with where my horizontal rails need to run. I need to run the rails directly along the purlins for effective anchoring.

Here's my question. How critical are the recommended clamping zones on the panels? Is this strictly for wind and snow/ice load? I'm considering running the rails (and clamps) outside of the recommended clamp zone. Sometimes as much as six inches outside of the recommended range.

Thoughts?

 

[Freddmc]

Are the purlins 1" thick or 1" wide?
Can you mount the rails vertical rather than horizontal.

 

[fr8tdrvr]

I don't know the how the engineering #'s would work out with the metal on top of the shingles. For direct to metal...Magerack or S5. You may need to mount directly into the rafters, considering they are load bearing.

 

[seanheinle]

Are the purlins 1" thick or 1" wide?
Can you mount the rails vertical rather than horizontal.

1" thick, 3" wide. Racking them vertically is an interesting idea. I already have the rail and mounts. It would just be a matter of seeing if I have enough material. I'm sure that's an option. Something I need to sort out a bit. Thanks for the idea!

 

[seanheinle]

I don't know the how the engineering #'s would work out with the metal on top of the shingles. For direct to metal...Magerack or S5. You may need to mount directly into the rafters, considering they are load bearing.

Looks like S5 needs to be into the roof and something structural which is my whole problem. I have a question out to Magerack. It looks like the MageBracket R may work when screwed only into the metal. Thanks for the tip.

 

[Freddmc]

I have a barn that has metal over shingles on purlins and don't think you want to just fasten the rails to the metal.

 

[Bob The Builder]

Hurricane Ida hit here last month. My neighbor had a Shed with 1x6 striping over roof rafters and tin nailed to that. They attached the racking to the tin using 3 self tapping 1" long screws in each location attached to the tin only. Well all solar panels landed 400 feet away in a ditch. They are still underwater upside down in a foot of water, some traveled another 100 foot to hit a pipe fence. A solar company did this.

 

[turbo6bar]

Hurricane Ida hit here last month.

Well all solar panels landed 400 feet away in a ditch. They are still underwater upside down in a foot of water, some traveled another 100 foot to hit a pipe fence. A solar company did this.

Did anyone's solar panels survive the hurricane? It hit land with tremendous wind speed.

IIRC, S-5! ag panel mounts have been tested with Ironridge rails. I don't know why they would make mounts that fasten directly to metal roofing if they won't pass standards.

 

[AlbaCORPS]

I have a similar style roof set-up. I decided to use FastJack posts. Swapping out the 3-1/2" lags for 4", through purlins to rafters

 

[Prefersdirt]

I don't have a metal roof. When I installed my panels I used ironridge. I would call them and ask for their solution.

 

[Bob The Builder]

Did anyone's solar panels survive the hurricane? It hit land with tremendous wind speed.

IIRC, S-5! ag panel mounts have been tested with Ironridge rails. I don't know why they would make mounts that fasten directly to metal roofing if they won't pass standards.

That is the only solar panels I know of not surviving it. 6 others I know did. In fact they protect the shingles as their neighbors roofs had damage!.

 

[Bob The Builder]

Under your shingles is plywood. I'd screw into the wooden strips using a roofing screw for wood Not sheet metal with a rubber washer. At lease 2 1/2" . You may get lucky and hit a roof rafter but it's not necessary. Go in your attic and check where the screws are coming through and adjust to hit a rafter if that makes you feel better but not necessary.

 

[Kornbread]

Under your shingles is plywood. I'd screw into the wooden strips using a roofing screw for wood Not sheet metal with a rubber washer. At lease 2 1/2" . You may get lucky and hit a roof rafter but it's not necessary. Go in your attic and check where the screws are coming through and adjust to hit a rafter if that makes you feel better but not necessary.

Most houses around here use 5/8" chip board for roof decking. I can put a screw into that and pull it out with a prybar. I would not trust something as large as a solar panel, in strong winds, to stay on the roof.

 

[JoeHam]

Same here, OSB would never hold a decent array in high winds.

I put just 2 panels on my shed roof this summer and had to pull a permit.

The only thing they checked inside was that I mounted to the rafters properly and did not just screw into the sheathing.

 

[Wellbuilt]

It’s easy to just add 4x6 blocking between your beams pushed up to the bottom of your steel and lag bolt thru .
I would use polyurethane sealant that stuff dosent come off
I used iron ridge , but have shingles

 

[740GLE]

There’s a reason why each racking manufacturer says you must hit a load bearing rafter to install racks.

If this is a 200 watt single panel prob not an issue but 1000-1500 pound array things can go wrong quickly.