question on overlapping aluminum sheets

[bronco]

I just wanted to double check with you guys first. when installing my aluminum sheets on the roof, it's the front sheet that overlaps the back sheet correct? The other question is at the front radius i am going to have a lap there as well and i've seen pictures of other tears with a lap there too, but the lap was back over the front at that spot. Would the purpose of that be for preventing any standstill water from working its way into the seam? What would be your best suggestion.

[kennyrayandersen]

Hopefully, you can get the first sheet up to the roof where the front sheet is at least flat and then it should be on top of the aft sheet so that water doesn’t get force-fed into the tear when you are going 65-70 mph down the road in some rain. Likewise you don’t want to let standing water run into the seam. You can get 10 foot sheets most places, but it is harder, and apparently, more expensive to get the 5 wide material. If you are running the sheet crossways, then that’s a little harder to do – you may have to make some kind of judgment AND make sure you are using some really good sealant.

[Duane King]

I think what you want to do is overlap seams with water fall in mind just the same way that you put shingles on the roof of a house. The aluminum panels should overlap 2".

I re-read your question and yes, do it just the way you described for the reason you said.

On my rig I used strap clamps to hold the dry aluminum in place so I could mark and pre-drill screw holes every 3" along the seam. Then I loosened the clamps far enough that I could put a 1/4" bead of sikaflex caulking along the screw line on the back side of each panel. When I re-tightened the strap clamps the caulking squeezed out of the screw holes. This was good because as I attached the hex washer head screws the caulking was under the screw head giving me a real tight seal. It wasn't all that difficult. On any given sheet of aluminum I only worked one edge at a time. Otherwise you run the risk of trying to do too much and losing control of the project. I began at the bottom front edge of the trailer and worked my way up and over the bow towards the stern. (a little boat lingo for 'ya there. . .) On only one seam did I change the order of overlap. For the reason you said. . .

One more thing. When I put in the screw heads I began in the center and worked my way left and right towards the edges. This was to avoid the potential of creating a "wave" in the material if it shifted on me while working.

Good luck

[bbarry]

I just wanted to double check with you guys first. when installing my aluminum sheets on the roof, it's the front sheet that overlaps the back sheet correct? The other question is at the front radius i am going to have a lap there as well and i've seen pictures of other tears with a lap there too, but the lap was back over the front at that spot. Would the purpose of that be for preventing any standstill water from working its way into the seam? What would be your best suggestion.

Have you already purchased your aluminum? If not, I would give serious consideration toward finding 5x10 or 5x12 sheets. It'll be a little more expensive, but (I think) worth it not to worry about seams in my roof! I don't know what suppliers you might have around you in Oregon, but around here you can get 5x12 sheets of 0.040 for under $90.

Brad

[bronco]

Brad, unfortunately the aluminum is bought already so i'll need to use what i got.
Thanks for the tips on the overlapping, strap clamps and predrilling sheets first. Any suggestions on what kind of cleaning agent i could use to wipe the excess caulk off that would'nt harm the aluminum?

[aggie79]

I plan on using blue painters tape on the underlying sheet to both help align the overlapping sheet and to contain the sealant squeeze-out.

[planovet]

I plan on using blue painters tape on the underlying sheet to both help align the overlapping sheet and to contain the sealant squeeze-out.

[bronco]

Thanks for the blue painters tape tip. That's a great idea!!!

[Micro469]

Or you can take them to someone that has a 5' brake and have the edges bent so that you can interlock the two pieces....

[Duane King]

If you use Sikaflex 221 as your caulking, squeeze out is not a problem. Just let the stuff dry and you can trim with a knife and peel off the excess. It cleans up real nice. I mentioned the 1/4" bead on the screw line. I placed another 1/4" bead parallel to the first so that there was plenty of caulk at the edge of the uppermost panel when screwing everything tight. I let that squeeze out and trimmed it later.

It wasn't a big deal to do this at all. I got direction for how to do it from Cary @ Camp-Inn trailers. I followed his instruction very carefully and it was no big deal. I was quite happy with the results. Just think it through. Dry fit the parts. Pre-drill the screw holes. Apply caulk once you know it is going down for the final time.

Oh, one last thing I forgot. Along the edges of the aluminum panels where the roof meets the sidewalls, don't use screws. Use staples from an air-nailer. This will hold everything while the caulking sets. Later you come back with RV molding and more Sikaflex and cover over the staples and trim the whole thing out real pretty.

You can do it. Good luck.

[bronco]

Thanks Duane for the detailed help. I'll definately take your advice and think each step through. How powerful of an air nailer would i need? Would harbour freight have something cheap? It would probably be the only time i would need it so cheap is always good. thanks again!

[bbarry]

Duane's suggestion of stapling down the aluminum on the edge is a good one. If you don't have a stapler already, you could:

1) Buy one from Harbor Freight. I've actually had really good luck with their air tools under light duty use. Watch for coupons and sales. Normal price for the 3/8" crown stapler is $19.99.

2) Use small brads to accomplish the same effect. You're basically just looking to hold the edge in place and provide a smooth flat surface for the caulking and trim to bed into.

3) Use screws, but back them out before attaching trim. If you do this, make certain to get caulking down in the screwholes.

Good luck,

Brad

[bronco]

Thanks brad. I do have a cheap pin nailer from home depot. It was supposed to be used for the headliner inside the tear but the bending force on the sheets of luan wouldnt hold with the nails and they popped through. Mybe it would work for this though.

[bbarry]

Thanks brad. I do have a cheap pin nailer from home depot. It was supposed to be used for the headliner inside the tear but the bending force on the sheets of luan wouldnt hold with the nails and they popped through. Mybe it would work for this though.

I don't think that's what you want. I imagine they'd blow right through the aluminum. If I were going to use brads, I'd use ones with a head and hand-nail them.

Brad

[bronco]

That wouldnt work too bad. If i had alot of other uses for a nailer i would get a good one. Just like me buying a beefed up riding lawn mower. It would be cool to have one, but the 20-30 square feet of yard i have to mow wouldnt justify me buying one! ha!