Mounting system for metal roof that that screws down to the battern

BjornMolin

Hi, all. I have a costumer who have a new trapezoidal metal roof, in this situation I would normaly sugest a standard mounting system that only needs screws mounted in the actual metall sheet. Like renusol, novotegra, k2 and Schletter all have standard solutions for. but the costumer says i wouldent be able to sleep if the panels are not fastend in the underconstruction. To mount with stock screw/ hangebolt is not an option becouse the rafters are only 45 mm thick. I would like to have verical rails that can be screwed down in to the batterns ( witch are 60 cm apart) for horizontaly placed panels. Anyone who knows such mounting system in Europe? I am based in Sweden by the way

MichaelK

In my own case, I'm constructing a unistrut solar frame for a metal roof. My solution is to mount 30cm unistrut sections directly onto the metal surface, held to the roof with at least 4 roofing screws. A machine bolt per section is bolted to the actual frame. So, the short sections allow 4 times as many screws per position than actually directly screwing the frame itself to the roof.

I came up with this design because of the high winds my cabin is subjected to. In the past, the metal roofing has been ripped off, simply peeling the metal away, leaving the screws imbedded in the sheathing wood.

Ampster

https://forum.solar-electric.com/discussion/comment/395630#Comment_395630

Are you using Aluminum Unistrut? If not I would provide some insulation between dissimilar metals to reduce galvanic corrosion.

MichaelK

I am unaware that they even made unistruts out of aluminum. All I've ever seen are ones made of plain steel or galvanized. For my own frames, I've used galvanized, which were carefully washed with degreaser, before painting. The frames on ground mounts already have had a couple of years of trouble-free service.

BTW, if you want to weld galvanized, you must be very careful not to breath any of the welding fumes (well you shouldn't anyway), because inhailed zinc vapor is very toxic.

Ampster

I don't know if it is technically Unistrut but I bought some aluminum and stainless steel strut from McMaster-Carr. It is the same shape and the fasteners fit.

mcgivor

Aluminum and stainless are available from Unistrut, usually special order,, I've used stainless in a salt water aquaculture facility, it's not cheap.though.

https://www.unistrutohio.com/stainless-steel-unistrut