Adhesive for Aluminum roof to plywood?

[Aubrey0418]

My husband and I are rebuilding a camper and are about to get to our roof install. We are doing a seamless aluminum roof which will be going over plywood. We want to avoid using any type of screws as much as possible to install this roof.
What type of adhesive would you recommend using for aluminum to plywood? 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?

[Aubrey0418]

We are building a rack using the tape. The design is hard to explain. We should have our roof and side walls up in a week and I'll show pictures

[Huntindog]

Aubrey0418 wrote:
Okay guys I'm really sorry for the late response we have been very busy on the build! I think everyone has agreed no plywood under the roof which helped me come up with an even better solution than screws. We really wanted to avoid screws because the original camper had water leaks all around where they screwed the roof. We have actually built a metal framing for the camper (added only about 100 pounds more than what the wood framing was) now we did this because we wanted a strong roof that could support our solar panels. Because our frame is metal and our roof is metal this allows to to use VHB tape. I have done a lot of research on this tape and man is it STRONG. They are starting to build some campers with it so it has been tested and has worked very well.

So here's our plan. We will be using vhb tape to attach the roof to the steel frame members, this will allow the roof to expand and contract just like screws. We will leave a lip on the roof to hammer over the edges of the aluminum siding. The "lip" will be hammered onto a vhb tape attaching it to the siding, hence avoiding even more screws. So our roof will be COMPLETELY SEAMLESS and with absolutely no holes..we are putting our fantastic fan in the back side of the camper not on the roof. I know it's unconventional but again I don't want holes in the roof. honestly I think it's time for a change for RVs and travel trailers..I mean how long is it going to take them to solve these water leak issues. Solutions are out there it's just extra money up front but worth it in the long run. I will definitely keep everyone up to date once the build is complete and after traveling, we'll see how it holds 🙂

How are you going to mount the solar panels?

[Aubrey0418]

Okay guys I'm really sorry for the late response we have been very busy on the build! I think everyone has agreed no plywood under the roof which helped me come up with an even better solution than screws. We really wanted to avoid screws because the original camper had water leaks all around where they screwed the roof. We have actually built a metal framing for the camper (added only about 100 pounds more than what the wood framing was) now we did this because we wanted a strong roof that could support our solar panels. Because our frame is metal and our roof is metal this allows to to use VHB tape. I have done a lot of research on this tape and man is it STRONG. They are starting to build some campers with it so it has been tested and has worked very well.

So here's our plan. We will be using vhb tape to attach the roof to the steel frame members, this will allow the roof to expand and contract just like screws. We will leave a lip on the roof to hammer over the edges of the aluminum siding. The "lip" will be hammered onto a vhb tape attaching it to the siding, hence avoiding even more screws. So our roof will be COMPLETELY SEAMLESS and with absolutely no holes..we are putting our fantastic fan in the back side of the camper not on the roof. I know it's unconventional but again I don't want holes in the roof. honestly I think it's time for a change for RVs and travel trailers..I mean how long is it going to take them to solve these water leak issues. Solutions are out there it's just extra money up front but worth it in the long run. I will definitely keep everyone up to date once the build is complete and after traveling, we'll see how it holds 🙂

[westend]

As was stated, no need to glue the entire aluminum covering. My seamed aluminum roof is still waterproof after many years. There is some type of coating on it and I have painted it with white elastomeric paint. It is attached at the walls and around vents with screws. Before I painted it, I sealed all of the through holes with Eternabond tape.

[JIMNLIN]

Having worked for 6 years in mobilhome mfg and then owned my own mobilehome/rv repair business and specializing in structures and exteriors for a while just about all roofs we saw and worked on had a fiber board of varius brands or luan type of plywood of various brand names across the roof ribs. This was some years back.
Now we did find some older cheap brand rv's that was just aluminum roofing over roof ribs. Fiber boards and luan was shot down with staples and aluminum roofing was glue down to help prevent roof rumble. We still see some older mobiles with old tires laying around the roof... for that reason.
Roof rumble did two things .

The worst was noise on windy days and especially nites the aluminum actually flapped in the center if not glued down. This is where a fast setting glue is used. Never add screws on a roof covering except around roof fixtures and roof jacks and in molding around the edges. The less holes up there the less chance of a leak down the road.

The second is like others have said aluminum constantly expands/contracts and if not glued down works the sealant till it isn't bonded anymore. Wind does this on a mobilehome. Same principle as the rv is pulled down the road at highway speeds.

Another thing we found is aluminum roofing gets brittle with age (20+ years). Especially if the unit was left outside in the sun.

[Huntindog]

theoldwizard1 wrote:
You are GENEROUS in predicting 10-15 years. MAYBE if you wash it a couple times each year, apply a UV protectant every time it is washed and store it out of the sun.

I am in Phoenix AZ. About as bad as it gets sun wise in the U.S.
I am on my second TT with over 10 years on the roof. Never washed it, never treated it, always in the Sun. No failures, no leaks.

My first used TT with an aluminum roof, had numerous leaks. All from sealant failures.

About the only advantage I can see for aluminum is it may hold up to tree branchs better, if one has the tendancy to rub the TT against them.

[NRALIFR]

What in the effin’ bloody heII is wrong with you Gdetrailer? You need to calm down. I don’t know what possessed you to think I was challenging what you wrote, but I assure you, I wasn’t. I believe it for cripes sake, why wouldn’t I? I was simply describing how mine is constructed, and since it sounds similar to the OP’s, how I would install the roof aluminum. How that managed to make you go off the rails so thoroughly is a mystery to me.

I honestly don’t understand why you felt it necessary to respond in such a hateful and belligerent way. If my posts are going to set you off so easily, why don’t you do yourself a favor and block me?

:):)

[theoldwizard1]

Gdetrailer wrote:

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.

You are GENEROUS in predicting 10-15 years. MAYBE if you wash it a couple times each year, apply a UV protectant every time it is washed and store it out of the sun.

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

You might convince me of TPO if it is installed by RV Roof Install. They give a 20 year warranty.

[badsix]

well it looks like the picture shows the insulation between the aluminum and the roof truss and top of the wall where it should be. also it should on the metal not only for heat purpose but to stop condensation. that's the proper way, it make no difference what you use felt, fiberglass or what ever. there needs to be something there to stop the condensation from getting the wood wet.
Jay D.

[Gdetrailer]

NRALIFR wrote:

Well, no offense intended, as all I know are the three TC’s I’ve owned. The 19 year old Lance In my sig, and two Jayco TC’s before that. All had a seamless aluminum roof, and there was definitely more than just the aluminum up there. Probably because TC’s don’t sit on a steel frame like a trailer, and their roofs are usually intended to be walked on. But, the construction of the trailer they’re rebuilding sounds very similar.

The only TC I’ve had to open up the roof on is the Lance, and there is a layer of some type of insulation between the aluminum roof, and the layer of plywood or luan that’s on top of the ribs. The voids between the ribs are filled with more insulation, then the ceiling plywood is on the inside.

The OP’s trailer that they are rebuilding also has plywood over the roof ribs, whether by their design or the OEM. If it were my camper, I wouldn’t try to adhere the aluminum to the plywood, but would put a thin (~1/8”) layer of some type of felt or foam insulation between. Mainly because I believe it will help quiet the roof when it rains, but it may also have some benefit in preventing condensation.

:):)

You don't believe me?

OK, how about some PROOF?

Put you money where your keyboard is and POST a pix?

I will start and end the argument with REAL proof of what I say.

The following is a photo I took of my first TT, a 1981 20ft trailer..



That is a pix of the side wall AND partial pix of the ROOF after I removed the interior paneling and fiberglass insulation.

There was NO, NOTHING, NADA between the aluminum and wall studs or aluminum roof and roof truss cross members. There was NOTHING, NADA, ZIP between the aluminum and the wood or insulation.

This same design was also used on my 1983 TT.

THAT IS STANDARD RV DESIGN AND WAY IT IS DONE, PERIOD.

Your "TC" could have been done differently if it had say an "Artic Package" but for most RVs the pix I posted above IS the "Gold Standard" of how it is done and yours would be the "exception" to that rule.

[ItsyRV]

theoldwizard1 wrote:
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 !"

The uncovered roof surface was metal framing along the sides, leading and trailing edges. Two additional metal ribs were placed at the air conditioner. Some of the bridging was also metal. The remainder of the ribs, bridging and attachment supports were wood. Between all this was the standard rock solid foam with a thin wood top surface.

The two part urethane adhesive was applied to the metal framing in a thick bead. The reminder of the surfaces had another type of thing lightly sprayed over it. I have no idea what that was. The aluminum was attached at leading edge with screws through the transition. As it was being laid down, a heavy floor roller was used to ensure contact and to make sure it was tight with no ripples, bulges or indentations. The edges of the roof (front, back, sides, and around the a/c opening, were screwed down through the transition and edge pieces. I did not get to see everything they used or did but was able to see enough.

Years later you can walk on the roof with no flexing at all. It's as if its one solid roof. There is no separation between the aluminum and the surface underneath. I belive they actually used three different adhesives; wood to wood, wood to metal, metal to metal. As a way of clarification, this was not done at an RV place but by those who service those emergency command type vehicles and trailers.

[GrandpaKip]

There are thousands of screws in the metal roof of my house. Never had a leak.
There are lots of screws in the roof of my camper. No leaks.
Every boat I’ve owned has had screws or bolts in the decks and coach roof.
Properly installed and maintained, screws are not really a problem.
Unless y’all aren’t going to have anything go through the roof, I wouldn’t worry about it.

[wing_zealot]

There are literally millions of metal roofs screwed down to wood substrates. You use specialty screws designed for that purpose and install them properly. Why re-invent the wheel. Follow the manufacturer's directions.

[NRALIFR]

Gdetrailer wrote:

badsix wrote:

NRALIFR wrote:
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

:):)

yes you will want the felt or some kind of insulation that aluminum is going to sweat not a good situation.
Jay D.

RV and Mobil home manufacturers NEVER put anything under an aluminum roof. Yes, I HAVE worked on mobile homes and I HAVE delt with RVs with aluminum roofs, there is NOTHING THERE, not even plywood.

The aluminum just lays over top the roof ribs..

Not saying it is the best way, just saying that IS what has been done.

You are always free to do what you think is best..

Well, no offense intended, as all I know are the three TC’s I’ve owned. The 19 year old Lance In my sig, and two Jayco TC’s before that. All had a seamless aluminum roof, and there was definitely more than just the aluminum up there. Probably because TC’s don’t sit on a steel frame like a trailer, and their roofs are usually intended to be walked on. But, the construction of the trailer they’re rebuilding sounds very similar.

The only TC I’ve had to open up the roof on is the Lance, and there is a layer of some type of insulation between the aluminum roof, and the layer of plywood or luan that’s on top of the ribs. The voids between the ribs are filled with more insulation, then the ceiling plywood is on the inside.

The OP’s trailer that they are rebuilding also has plywood over the roof ribs, whether by their design or the OEM. If it were my camper, I wouldn’t try to adhere the aluminum to the plywood, but would put a thin (~1/8”) layer of some type of felt or foam insulation between. Mainly because I believe it will help quiet the roof when it rains, but it may also have some benefit in preventing condensation.

:):)