Roof Material

[mmmc101]

What is everyone's thoughts on roof material: Alum vs rubber. I don't intend to be walking on the roof except for possibly A/C or antenna maint. Would appreciate your input.
MMM

[GENECARP]

I have fiberglass, I like it, G

[Bob86ZZ4]

I think mines aluminum. No maintenance. I think those rubber membrane roofs require some maint. don't they?

[volvoman]

we had a corrugated metal roof on our shop. rusted and started leaking. had a roofing company frame around edges and in to 8' wide sections. they put 4' x 8' x 2" thick insulation down to cover steel. then glued down rubber roofing material. its lasted about 8 years now with no maintenance. its a black material. he told me they make it in white also. i'm going to put white on my motorhome when i get that far. he said he would sell me material at cost had help me at no cost. 102" wide and 31' long would be about $500.00.

[Bob86ZZ4]

I don't know. Do any of the t/c builders use rubber membrane roofs? I'd try to talk to some of the builders and see what they use? Hawk Engineering is a frequent poster here, maybe he'll chime in.

[GENECARP]

I think some may still use rubber, we use rubber in certain residential and more commonly in commercial settings..Rubber is a good material but I don't think it will hold up as well as fiberglass or aluminum. UV seems to break down the integrity of rubber quicker than other choices. That being said rubber is easy to work with, and can be reconditioned easily....G

[Dragonslayer140]

I work in the commercial modular building industry, and we use EPDM rubber membrane roofing on a large number of buildings. It comes 45 mil. and 60 mil thicknesses, in both white and black. properly installed on a commercial building it can come with a 20 year warranty. I replaced the factory roof on my aging motor home with the 45 mil. white about 6 years ago, and have had no leaks or damage even with small branches falling on the roof during the winter. When i finally get around to building my T/C I will use the 60 mil for some extra thickness as i won't have to worry about the extra weight. I do carry a scrap piece of roofing about 2 feet square and some eternabond roofing tape in case of any roof damage on a trip. The eternabond patch can be applied on a cold wet roof if needed.

[mmmc101]

I decided to visit as many RV repair centers that were reasonably close to obtain their input. I posed the same question to all of them: If you were building your own RV which roof material would you use,rubber or alum? ( I did not mention fiberglass as I break out everytime I work with it)

Of the five places I visited, three said alum,two rubber. Most thought the alum would be more durable and less likely to be damaged by tree limbs. Two of the locations were in the process of of replacing rubber roofs on RV's.One had lost it's bond to the roof and was floping in the breeze,the other had a 3' rip from a tree limb ( new RV). One site said they had installed a rubber roof on top of an alum one at the custmer's request. They didn't know why since the roof was not leaking.(customer is always right)
Installation is pretty much the same.The surface needs to be clean,dry and smooth. Most warned not to use treated plywood or plwood sheathing.Both still contain moisture or chemicals that could prevent a good bonding. They reccomended kiln dryed plywood with one side sanded.(no knots or imperfections)
Cost for alum was only slightly higher than rubber.For my application 102" X 144" the alum is just over $500 (.040).The rubber was $386 for 63 mil.
The alum can be obtained in .024 much cheaper but I think thats to thin.
Given all the input I think I will use alum for my application since I am familiar with that and I have never worked with the rubber before.

Thanks everyone for your input! I learn something new everyday.
MMM

[HawkEng]

Yep, ALUMINUM! We have repaired lots of the rubber roofs for guys. We have used 024 and thicker depending on customer.

[JACC0811]

Sorry for bringing up an old post, but I couldn't find an answer to a question I had. Anyhow, what is the typical thickness of the plywood substrate when using the rubber? And also, would you use the same for an aluminum roof, or just attach the aluminum to your framing?

[mmmc101]

Somewhere on here is a thread discussing that very subject, I just can't find it. If I remember correctly, the consenus was 3/4" plywood for substrate. I suppose you could get away without it using alum. as many converted commercial trailers do not have any. Since I am mounting the A/C,vents and TV satelitte on the roof,I felt 3/4" was the way to go. It also adds some insulation value. Just my opinion. MMM

[dgorila1]

When a roof cover is made with aluminum sheet, is it made from one continuous length of sheet so there are no seams? How is it secured (i.e. adhesive, screws)?

[mmmc101]

Those that I have looked at are one continuous sheet of either .024 or .030 alum. They used no adhesive. It was secured with alum trim and screws around the perimeter. I think I am going to use some adhesive as well just to make me feel better.
MMM

[hot rod]

I have had a number of race car trailers with similar construction on the roof to a TC. My favorite had 3/4" plywood under the aluminum which made for a nice walk on roof, but a bit heavy of course. I would suspect you could easily get away with 1/2" as well. Current trailer just has .030 aluminum with nothing underneath. If you work on top you have to step carefully from rafter to rafter. I took a can of spray paint up there and marked the rafter locations so I could walk around easier. Also, having wood underneath makes everything a whole lot more solid when adding things to the roof like tank vents, refrigerator vent, tv antenna, etc.. In all cases the aluminum is one piece, it comes a standard width in a roll and you buy it by the foot. In a perfect world the top aluminum is folded over the edge, then the trim covers that and the screws run in from side so there are no holes in the top, and then a bead of sealer between the aluminum and the trim. I just spent a whole day resealing the roof on my Pace trailer last weekend (10 years old, it was overdue) and I was surprised to find that the roof metal on that one did not overlap the edge, it just lays flat, and had the trim screwed down from the top. They just used a wide band of sealer to cover the joint and screw heads. Would not be my first choice, but it seemed to work well enough until the sealer got older and started to crack. I have never had the roof glued down on any of my trailers, I don't know if that is a good idea or not. I know my roof really expands a lot on a hot day where it is noticeably warped looking as opposed to nice and flat on a cool day. Perhaps the metal needs to be able to move around a bit for expansion. Just thinking out loud there. I do think it would be quieter while moving in a TC, aluminum rattling around is surprisingly loud when you are driving, I always use some silicone behind a piece of aluminum before I screw it down to keep it quiet.

I would not even consider building one without insulation in the roof. The more the merrier. I've had trailers with and without and the ones without insulation are ovens in the summertime even with the doors open. The ones that were insulated were always nice and cool inside. This Pace has wood strips on the bottom of the roof square tubing to space the ceiling down an extra inch leaving about 3" for fiberglass insulation. But I don't really think you can have too much.

[mmmc101]

HotRod,
You make a good point on the expansion/contraction of the alum. Had not thought about that. Adhesive could very well create a problem. I am using 3/4 plywood on the roof and 7/16 plywood liner inside. With 2 inch framing the walls/ceiling,filled with foam,should be fairly well insulated. MMM