To skin with 1/8" ply before AL or not

[mark Holbrook]

Hi,
I am getting close to applying the aluminum top on my tear and wanted to discuss the pros and cons of applying 1/8 ply first.

Pros seem like: smoother roof once done, extra strength

Cons: More work, heavier trailer, more oil canning

I am following the Kuffel guide and am leaning towards just using the aluminum.

Thanks for you thoughts!
Mark

[aggie79]

I used 1/8" plywood under my 5' x 10' x 4' teardrop before adding the aluminum. I didn't keep track, but I think I used around 7 sheets for the sidewalls, roof, front wall, and hatch. At 11 pounds per sheet, that added about 80 pounds to my build.

The use of plywood has no effect on oil-canning if you live somewhere that has temperature extremes. I have some slight oil-canning when the temps get above 85-90 degrees, but it isn't noticeable unless you push on the aluminum, and it goes away when it gets cooler.

If you use .040 aluminum or thicker, you probably don't need the plywood skin. The main reason I used it was to minimize rock dings, and, because the plywood was coated with epoxy, it helps provide another barrier against moisture intrusion.

Take care,
Tom

[mark Holbrook]

Thanks for your input Tom. I really admire your build so your comments go a long way. Now I'm leaning towards using the ply.

[electronicx]

I'm close to the point in my build where I can put the roof on. I cant find any 1/8 inch plywood without ordering a large quantity. So I'm going without and the aluminum will go right on top of the ribs. I did put the ribs a little closer together than some do. I might use .05 aluminum but I want to compare in person before I choose.

[Danny]

Hello, I used 28 gauge galvanized steel over plywood on my first build. considering just using metal over ribs on my next build..Has anyone used steel over ribs before? I was thinking doug hodder has done this before?..P.S., I think Madjack just skins over the ribs on his gator tear,also, 1/8 masonite will work and, it bends real well.. Danny

[madjack]

...yep, no ply here for the roof...I put my spars on 8" centers and used .040AL directly over 'em...going on 4yrs and no problems...it is the only way I would do it...if I did it again............
madjack

p.s. I used 3/4ply for the walls, epoxied the edges...used a couple orso staples to locate the AL and predrilled all holes when applying the RV style insert molding, squirting a bit o' caulk in each hole before screwing it down with SS#8x1" pan head screws..............mj

[Danny]

...yep, no ply here for the roof...I put my spars on 8" centers and used .040AL directly over 'em...going on 4yrs and no problems...it is the only way I would do it...if I did it again............
madjack

p.s. I used 3/4ply for the walls, epoxied the edges...used a couple orso staples to locate the AL and predrilled all holes when applying the RV style insert molding, squirting a bit o' caulk in each hole before screwing it down with SS#8x1" pan head screws..............mj

Good job MJ! If aluminum has held for 4 years, 28 gauge steel should do very well..We do get large hail on the great plains, thus, steel makes good sense.. Danny

[planovet]

I put down a layer of 1/8 ply before my aluminum but as MJ has said, you don't have to. It's all up to what you want to do.

[doug hodder]

.Has anyone used steel over ribs before? I was thinking doug hodder has done this before?Danny

Nope...wasn't me. I put ply under all my aluminum skinned trailers. I camp up in big trees and have them at home. The ply helps keep it from getting too dented from dropping pine cones and other stuff. Out here, never camp under a sugar pine when they are dropping cones. A sugar pine cone can run 15" long and if it's green...it's like a meteorite dropping!

I think it's worth it, and it really doesn't add that much weight, compared to the repairs that may have to be done if it's punctured. Doug

[J.Heyboer]

I am going with no ply and .040" aluminum on the roof as MJ suggested.

My walls are stick built and I am considering attaching the aluminum directly to the 1x4 framing with no outer layer of ply.

I just don't think its needed. Has anyone else done this on the side walls?

[grant whipp]

FWIW, I'm a firm believer if using a 1/8" underlayment before skinning with aluminum (even steel). Even though I float my roofs, the plywood (or even masonite) adds an extra layer of strength and backing should any part of the roof receive a severe impact (I recently received a nasty impact from a "flying" steel-framed lawn chair on the front of my personal trailer ... if it weren't for the 1/8" plywood backing, I'd have a big hole in my aluminum instead of a sizable "I can live with that" dent ... ...!). It also helps minimize the damage in case of a severe hail storm.

As far as the sides go, gluing to a plywood substrate will give you a smooth flat surface with no "patterning through" of the inside framing.

Good Luck, and as always ...

CHEERS!

Grant

[asianflava]

I put 2 layers of 1/8in luan on the roof then covered it with Aluminum. In retrospect, only needed 1 layer.