Adhesive for Aluminum roof to plywood?

On my roof, (aluminum to wood & metal framing) they used 3M's Scotch Weld urethane adhesive. It was applied using the bead and roll method. The roof section was also 8' X 16'.

Two big issues when trying to glue metal to wood.

• Preparation. The aluminum should be "scratched" a bit (ScotchBrite) and wiped down with acetone. Light sanding on the wood and a tack cloth.
• Expansion rates of the two materials. Aluminum expands a LOT when heated (sun exposure). Wood only expands a little when it is warmed. BAD COMBINATION ! No adhesive can survive that for long periods !!

Aubrey0418 wrote:
Also it's a 16ft camper so we will have to find a way to apply adequate even pressure throughout while laying the roof down..any suggestions on that?

Lots of cinder blocks or other heavy weights.

theoldwizard1 wrote:
Two big issues when trying to glue metal to wood.

• Preparation. The aluminum should be "scratched" a bit (ScotchBrite) and wiped down with acetone. Light sanding on the wood and a tack cloth.
• Expansion rates of the two materials. Aluminum expands a LOT when heated (sun exposure). Wood only expands a little when it is warmed. BAD COMBINATION ! No adhesive can survive that for long periods !!

Aubrey0418 wrote:
Also it's a 16ft camper so we will have to find a way to apply adequate even pressure throughout while laying the roof down..any suggestions on that?

Lots of cinder blocks or other heavy weights.

So are you saying we'll have no choice but to screw it down?

theoldwizard1 wrote:
Two big issues when trying to glue metal to wood.

• Preparation. The aluminum should be "scratched" a bit (ScotchBrite) and wiped down with acetone. Light sanding on the wood and a tack cloth.
• Expansion rates of the two materials. Aluminum expands a LOT when heated (sun exposure). Wood only expands a little when it is warmed. BAD COMBINATION ! No adhesive can survive that for long periods !!

Aubrey0418 wrote:
Also it's a 16ft camper so we will have to find a way to apply adequate even pressure throughout while laying the roof down..any suggestions on that?

Lots of cinder blocks or other heavy weights.

Best solution Hex self tapping stainless sheet metal screw w/sealing washer These will hold in plywood.

Shop for similar WITHOUT the rubber washer and you can buy those cheap.

Aubrey0418 wrote:
So are you saying we'll have no choice but to screw it down?

ItsyRV wrote:
On my roof, (aluminum to wood & metal framing) they used 3M's Scotch Weld urethane adhesive. It was applied using the bead and roll method.

ItsyRV used an urethane adhesive which DOES have more flexibility than most adhesives. I assume by "bead and roll", he meant that a bead of the adhesive was applied to the wood (like where the rafters would be) instead of the entire surface (like a contact cement), the aluminum is then laid down and rolled.

I am no expert, but I think I would add the screws over the line of the adhesive. "Belts and braces !"

why not use the EPDM rubber roofing material used on most RVs. its probably not much more than aluminum in cost and probably easier to install. use Dicor self leveling sealer for any penetrations and you'll be good to go. I sure wouldn't want an aluminum roof with screws of any kind in it if I was looking for long life. Google RecPro, Dicor EPDM roofing
Jay D.

badsix wrote:
why not use the EPDM rubber roofing material used on most RVs. its probably not much more than aluminum in cost and probably easier to install. use Dicor self leveling sealer for any penetrations and you'll be good to go. I sure wouldn't want an aluminum roof with screws of any kind in it if I was looking for long life. Google RecPro, Dicor EPDM roofing
Jay D.

Because "EPDM" and any other flexible non metallic roof solution is a short lived 10yr-15yr fix.

Aluminum can often go 30yr-50yrs without being replaced which makes aluminum far cheaper but yet far superior overall. RV industry moved to using EPDM, vinyl roofing because it is cheaper than aluminum roofing, requires less skill and less labor to install which = MORE PROFITS. It was not because it was better than aluminum!

As far as the OPs question, aluminum roofing does not need glued down, it is secured via screws around the entire perimeter, the middle floats. In fact it needs to float to allow for expansion and contraction with temperature changes.

The only places that will need screws is vents to hold the vents in place.

The perimeter screws are hidden via the trim pieces at the top of the walls.

The aluminum roofing is folded down over the side walls, then the top side wall trim is installed, a bead of butyl caulking is what is used to water proof between the roofing, walls and trim.

The aluminum sheet on the roof of my TC isn’t glued to the wood at all. IIRC there is a layer of felt or closed cell foam between the aluminum and the wood, but it’s held down by the perimeter trim and screws. I don’t think I’d try to full-spread glue it.

I would also pass on the EPDM, TPO, or any other flexible membrane roofing. Nothing beats aluminum.

In other words, what he said ^ :B

:):)

No issue with adhesive, should be used, but screws are also necessary IMO.

Another option :

My Jayco has a one piece galvanized steel roof. It's almost 30 years old and no leaks.