Thin plywood above the roof braces?

[drcurran]

In my trailer, and I think I notice in others, there is thin (1/8" I think) plywood above the roof braces. Why? And my guess is it is best to just insulated on top of that thin ply. Yes? Thanks for the help.

Dan

[Stealth TDI]

It may a little to do with support. But I initially figured them to be to reduce or eliminate vibration, noise, and/or damage from chafing.

[David_L6]

Both of my trailers have that but I don't have a clue what it's there for.

[len19070]

I was told at a factory seminar once that it was to reduce potential Hail damage?????

Happy Trails

Len

[Gadget Man]

I think it's all of the above.

My trailer had lots of 1/8 inch luan up between the roof channel iron and the aluminum sheet for the roof.

I know it adds lots of strength to the outer skin. be it from hail, tree branches, or baseballs. I'm also sure it helps support the skin while traveling at 70 mph down the highway.
Either way, I'm glad it's there, I added some more from some sheets I had laying around the shop.

I did use some wooden shims to help support the sheets where they didn't quite reach.



You can sort of see the shims on the right side ceiling they go cross-ways to the roof braces. I added a few more strips close to the center.

[halfdome, Danny]

Condensation could be another reason. Danny

[elmo_4_vt]

I always assumed it was to add a little bit of bow to the roof for water run off without having to custom bend the metal.

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[BC Dave]

all of the above I beleive; gives some regidity to the 20 ga(?) galvanized rood on mine; I wish they had used something thicker 1/4 or 3/8 and wider on mine is just 4X8 but the trailer is 5X10.

Also the sheet metal is laying flaton the roof so it would sag without the extra support.

[GPW]

Wouldn’t thicker AL sheeting do the job as well , without the potential for Rot ... Sorry to be a skeptic , but we’ve had some bad experiences with unsealed plywood on recreational vehicles, even inside ...
Seems like the Best job would be to spray the metal roof (and walls ) with a good 2 part foam that would not only strengthen and insulate , but also not rot ... A process well proven in our old Kustom van conversion days...
Granted it is more expensive than a thin sheet of cheap plywood ... but if the manufacturer skimps on the metal thickness of the roof, a little plywood isn’t going to do all THAT much ...

We’ve seem many many CTs around here and some , the better constructed ones, do just fine ... the poorly made units becoming “shabbyâ€

[BC Dave]

[quote="GPW"]Wouldn’t thicker AL sheeting do the job as well , without the potential for Rot ... Sorry to be a skeptic , but we’ve had some bad experiences with unsealed plywood on recreational vehicles, even inside ...
Seems like the Best job would be to spray the metal roof (and walls ) with a good 2 part foam that would not only strengthen and insulate , but also not rot ... A process well proven in our old Kustom van conversion days...
Granted it is more expensive than a thin sheet of cheap plywood ... but if the manufacturer skimps on the metal thickness of the roof, a little plywood isn’t going to do all THAT much ...

We’ve seem many many CTs around here and some , the better constructed ones, do just fine ... the poorly made units becoming “shabbyâ€

[8ball_99]

Mine has a layer of Thermo ply between the roof and ceiling supports. I had the factory add it to reduce the heat transfer. They told me it would also make the roof stronger.. Maybe the used the luan for the same reasons.

[NathanL]

I always assumed it was to add a little bit of bow to the roof for water run off without having to custom bend the metal.

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That's what it is for in my trailer since the strip is only about 18" wide down the middle.

It also puts the top under tension just enough that it doesn't pop in and out with change in temperature etc...

[GPW]

Speaking of changes in temperature ... We’ve been studying CTs for several years now and noticed the ones made in the summer don’t wrinkle as bad as the ones made in winter ... Think of it this way ... If the skin is applied when it’s in it’s heat expanded state (summer heat) it will only get tighter when it’s cold ... If it’s applied in the winter (cold ) when it’s contracted , during the summer the Al will expand and wrinkle up ... Just an observation ... Seen many trailers that during summer turn into a wrinkly mess... some never seem to wrinkle ... all depends when they were made ... Hottest part of the summer seems like the best time to get one made ...

[BC Dave]

Speaking of changes in temperature ... We’ve been studying CTs for several years now and noticed the ones made in the summer don’t wrinkle as bad as the ones made in winter ... Think of it this way ... If the skin is applied when it’s in it’s heat expanded state (summer heat) it will only get tighter when it’s cold ... If it’s applied in the winter (cold ) when it’s contracted , during the summer the Al will expand and wrinkle up ... Just an observation ... Seen many trailers that during summer turn into a wrinkly mess... some never seem to wrinkle ... all depends when they were made ... Hottest part of the summer seems like the best time to get one made ...

lol!

your observant!

... so best to buy in the fall?