How many brackets for RV roof mount?

GuardianZX9

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DAMMIT. Somehow I never thought of this.
I would probably use carbon reinforced filament, but that is purely my opinion.
Please put that up on thingaverse so it's easy to find!
I will see what I can do.

FYI, these are printed in ASA as a test, I have another set printed with HIPS and ABS just to see how they hold up over time. ABS would be the cheapest, and no need for high infill or expensive filament, they are VERY thick, just use 3-5 perimeter shells for extra strength.
 

GuardianZX9

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Original is on PinShape


Alternate versions on Thingiverse
 

eXodus

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I am using these, 3D printed, super strong, very lightweight and cheap to print if you are able.
what filament are you using?

I'd read that many are not very UV resistant and will get brittle over time. Did you paint yours?
 

GuardianZX9

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what filament are you using?

I'd read that many are not very UV resistant and will get brittle over time. Did you paint yours?
The first set I printed I used ASA(UV resistant) I plan to print a few more copies with HIPS, ABS and PLA just to see how they hold up over time. I did not paint, I used white ASA filament.
 

helloterran

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Feb 28, 2022
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It seems we're using the same panels, and I used 8 brackets. The trusses on my roof are 15 inches apart, so I ended up drilling new holes on the panel frame to ensure at least 3 brackets on each side get attached to the trusses.

Otherwise the plywood sandwich really offers next to none holding power --- using renogy self-tapping screws, I was only able to get finger tight. Even the lowest torque setting on my drill would strip it. With on-trusse screws I was at least able to get to setting 3-5 out of ten.
 
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Paul_R

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My panels are also 58x26. I used 6 brackets per panel, three #14 screws per bracket with the center screw in an aluminum joist. Brackets are 4" long and mounted with Eternabond tape followed by Dicor lap sealant all around and over the screws. Also slathered the screws with Dicor prior to driving them in. I used self tapping screws, not self drilling. The roof is rubber with 3/8 plywood over the roof joists.
 

Doug Wall

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I have just browsed through this topic, so I may have missed some things. One thing that struck me was the thought of screwing structural support screws (for panels) into skin aluminum/styrofoam/1/4 luan. For me, this would be a no-go! I would bolt through with 1/4” stainless, with fender washers on the inside, and thread locker on all nuts. Better safe!
 

acdoctor

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How? A piece of foam insulation sandwiched between two pieces of thin plywood doesn't seem all that strong to me. I did look this up before my prior post. I thought for sure that I would find something that said it was not a walkable roof, but that was not the case at all. I was surprised, given your description of the roof.
It’s all glued together making a truss like. Similar to a hallow core door.
 

Doug Wall

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It’s all glued together making a truss like. Similar to a hallow core door.
Glued together doesn't make that much difference! I'm talking about fastener pull through. 1/4" plywood doesn't take much to pull a screw out, and styrofoam takes nothing. What are the RV manufacturers specs for mounting heavy objects on the roof?
 

acdoctor

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Glued together doesn't make that much difference! I'm talking about fastener pull through. 1/4" plywood doesn't take much to pull a screw out, and styrofoam takes nothing. What are the RV manufacturers specs for mounting heavy objects on the roof?
I was referring to the walking on aspects.
I think there are some designs that are just not suitable for roof mounted panels with out heavy modifications.
I have 3/4 plywood roof and I still located and anchored into the 1/8 thick steel frame beneath.
 

12VoltInstalls

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What are the RV manufacturers specs for mounting heavy objects on the roof?
A brand new one that came in to a place I worked said in the manual, “Roof mounted accessories are not recommended. Accessories should be installed by a qualified dealer using professional methods.”
The roof was membrane over what was basically cardboard, and the “trusses” looked like wood strapping and scrap plywood were used to build them.

It’s a scary thing, imho. Camper roofs.
 

Hedges

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Peel and stick panels would seem an option for the roofs without strong attach points.

Do the edges have suitable material in them? Similar concept to a roof rack clamping on gutters, if you screwed into the sticks or frame there, and had panel rails spanning width of roof?

Composite structures are amazingly strong; you'd be surprised at what they are used to carry. But transition to hard points has to be designed into the structure.
Just bolting a roof rack through two layers of sheetmetal on my pickup roof, I used large washers but felt care was required.
 

Paul_R

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As long as the roof is flat or only very slightly curved, I've had great success with Scotch VHB tape on aluminum roofs. It should work on fiberglass as well but it's just not an option on a rubber roof. I do use eternabond tape under the mounts on my rubber roof but just for additional sealing.PXL_20220518_183338354.jpgPXL_20220518_190811518.jpgPXL_20220619_153949829.jpg
 
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12VoltInstalls

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Scotch VHB tape
I’m not going to run with it but there’s no way I’d trust other people’s lives with that. There’s tons of trailers sheathed with that stuff. I’ve fixed a few. Mechanical fastening is sure.
 
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