MCI rooftop layout

[dtcerrato]

If you decide to use Rivnuts,, then be sure to measure thru the drilled holes to determine the TOTAL THICKNES OF ALL PANELS.. A rivnut has to have the correct "gip length" to hold properly..>>>Dan

Just like a rivet...

[Utahclaimjumper]

Just like a pulled rivet.>>>Dan

[windtrader]

OK, looks like the rivet nut is the winner. I like how you have a threaded hole to bolt stuff into the rivnut and very easy to remove.


At quick glance, it seems there are different products sold as rivnut. Which brand do you recommend? Also, which style rivet installer, looks like different styles.


thanks

[richard5933]

Can't speak to the different brands, but I can speak to one point - when you use the install tool you've got to practice to get the required pressure down. Too much pressure on the install tool and the threads distort. Too little and the rivnut wiggles in the hole or pulls out.

Explore different ways to seal the rivnut as well, as the ones I've found don't have any built-in seals to make them water tight. Usually I use a neoprene washer against the rivnut, then a thin flat washer, and then whatever I'm trying to mount.

[dtcerrato]

The best mechanical means to weather proof a riv-nut fastener penetration is with slight conical neoprene bonded SS washers. There are also SS neoprene "well nuts" that work similar to a riv-nut but are a neoprene barrel instead of a metal barrel which expands underneath the surface & have tremendous holding power & a tight seal. Our whole bus barn which is constructed of corrugated FRP siding on structural metal framing has thousands of these well nuts including on the almost flat roof line. It was a fastener of the trade in industrial cooling tower construction where forced water flow was kept inside of the structure. They are the ultimate & free in my case...

[windtrader]

Any thoughts on spacing and placement of the rivnuts along the unistrut. Some say not to mount the railing flush to the surface to allow water to flow under the railing. What I'm thinking is to use a piece of aluminum plate maybe 4" long, 1/8" thick, put a hole so rivnut can go through. That would provide a strong stable platform for the unitstrut to lay against.

[luvrbus]

Are you framing the 14x14 cut out with Unistrut ? the big guys with 5 or 6 roof tops use no rivet's or nuts only strips of metal with the 3m 5200.There are 2 strips of 1/8 metal with a 14 inch spacing bonded to the roof from front to rear between the roof bows.ac units with the 90 to 100 lb weight spread out has very little per square inch weight   

[Dave5Cs]

Nope he is installing his Solar panels full length
https://www.youtube.com/watch?v=WpATnkmKzYI

[luvrbus]

Nope he is installing his Solar panels full length
https://www.youtube.com/watch?v=WpATnkmKzYI

So he is leaving the Unistrut exsposed on the roof 

[chessie4905]

Yes, just like rivets and pop rivets.

[luvrbus]

I wouldn't attach or drill holes in the lap seam they are bad enough about leaking to began with ,when the membrane gets old and brittle   

[windtrader]

Many styles of Rivet nuts to choose from. I'm pretty impressed how strong some are. One video shows a guy who keeps cranking a machine bolt down wondering how tight it will go. Kept turning until the he twisted the head of the bolt. Not an ad so, I'm assuming it was not an altered bolt.


I'm feeling a lot better that this will hold up fine. Thinking I will cut four inch lengths of aluminum flat stock for a riser to keep the strut off the surface of the rooftop. Then 3 rivet nuts going through the strut, plate, and rooftop material will hold them fine. Place one every 16" or so. without any calculations or bench testl hard to know how much force the rails will hold but a lot more than what I tried earlier. LOL

[windtrader]

I wouldn't attach or drill holes in the lap seam they are bad enough about leaking to began with ,when the membrane gets old and brittle   

I'll have to think about that since the tradeoff is there is double roof material and also potential for drilling into the cross-member for maximum strength.

I'll need to go look at how the lap is done but one would hope just like shingles they would have put the upper lap over the lower one as it curves over the side minimizing leakage if that is the concern.
Well, that was quick. The overlapped areas are cross ways, the bulk of where the strut will be mounted is single layer so no concern on leaking from lapped material. At those junction. I could not place any rivet nut there.

[luvrbus]

You need  to make some calculations on runs that long,if you over do it attaching the Unistrut and don't allow for expansion and contraction you could end up with a mess like some of the schoolie crowd did   

[Utahclaimjumper]

It would be easy to do that run in several sections with 1/2 inch gaps at the section ends..>>>Dan