Panel Mounting on Corrugated Metal Roof

[ianb]

Hi all, I was wondering about experiences involving corrugated metal roof mounting.

The problem is that most systems going in around my location will be on agricultural buildings or large sheds with corrugated metal roofs. In most cases the roof truss' are on 4 foot centres and the 2x4 strapping on 2 foot centres perpendicular to truss'. The system being installed uses L-Feet and unirac rails. With the roof structure being the way it is L-Feet should only be mounted over strapping over the truss, this ends up leaving a 71/2 inch gap vertically between the 4 rows of panels. Preferably I would like to have a 1 inch gap but unless L-Feet are moved closer together this cannot happen. With juggling the panel overhang over the perlin I can get a 1 inch gap between rows 1,2 and 3,4 but in between row 2,3 will have a 14 inch gap. The only remedy I can think of is to insert pieces of 2x4 parallel to the truss in between the existing strapping as to not crush the metal when tightening down lags.

The next problem lies when a corrugated rib lines directy up with the truss. In the case where L-Feet are attached over strapping over truss they can simply be moved left or right off of the truss and still catch 2x4 strapping. In the case where extra pieces are cut and inserted parallel to the truss if you move left or right of that you will not be over strapping and only into sheet metal and air. The only remedy for this I could think would be to insert and scab in place 4 foot long 2x4's perpendicular over two truss' where the L-Foot would go.

As you can see to make the system look very pretty with 1" gaps horizontally and vertically is very difficult. Personally I like the idea of a 14" gap in the middle of the array as an access for service as well as the L-Feet being over strapping over truss. However the customer would like to see only 1" gaps if possible. Any ideas or input on how to make this happen without adding all kinds of boards would be greatly appreciated.

[dwh]

I can't say how well it would work for PV mounting, but I've seen all sorts of gizmos, widgets and doohickeys welded to corrugated metal buildings - including the roofs.

[icarus]

There are mounting clips available for standing seam steel roofing, amongst others I'm sure"http://www.sunwize.com/info_center/pdf/S5_Universal-PV-Anchor_5-08.pdf

Tony

[Cariboocoot]

Be advised that welding to galvanized roof panels will ruin them; the zinc is gone, the rust begins.
Simplest solution is to add structural members underneath as needed to distribute the load.

[Dave Sparks]

You probably do not want problems with the whole structure coming apart. $500 for an engineer to calculate loads and advice might be the way to go.

Marine primers and paint will stop the rust or at least slow it for a few decades. Love DuPont!

[realdeal]

We just mounted 420 roof brackets to a corrugated metal roof on a barn, we have had some of the same questions and issues. We had a structural report done on the building. There recommendation was useing an anchor bolt, basically a half lag/half threaded bolt. We used a high end sealent, then mounted the L-feet and unirac rail. The only problem that i ran into was, consistently hitting the truss, and the trusses not being square to the roof, leaving the rails running less than square to the roof. We also left the space in between rows. Ill try and update with how the final product turns out.

[mvrck]

You may have also tried the CorruBracket from S-5!

http://www.s-5.com/clamps/index_1032.cfm

We have used the VersaBracket with good success.

http://www.s-5.com/clamps/index_71.cfm

Good Luck!