VanDweller Community Forums

Full Version: What side polysio goes against van roof?
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
I have GAF polysio this. . . http://www.homedepot.com/p/GAF-0-75-in-x.../204322724

It has a bilaminate (aluminum and kraft) faces bonded to a core of polyiso foam.

Should the aluminum side be against the van roof?

Thanks
A SEEKER
If you want to keep the heat out them it should face the roof. If you want to keep heat in it should face in.
But, if you face it up against the roof without an air gap it won't be very effective as heat will conduct through the metal roof into the Polyisio. I did that with Reflectix myself but failed to leave an air gap.
How do you plan to attach it? The reason for asking is because when I used it, the facing tended to peel away from the Polyiso. I decided to metal tape the edges to make the facing more resistant to peeling. Also found using good quality double sided sticky tape worked well for keeping in in place. There's a good assortment at Home Depot.
Luisafernandes I thought polysio did not need air gap and could be placed directly on roof. My main concern is stopping condensation drips in the winter from propane heat. maybe I could make spacers and small air gap.

freenez2 not sure what will attach with. I looked at double sided tape and all I found was only rated to 105 degree and thought it may not stick in summer heat. So may still use combination of tape, permatex and wood strips.
Any other advice would be much appreciated as I want to install now.
Thanks
A SEEKER
(10-21-2014, 11:14 AM)A SEEKER Wrote: [ -> ]Luisafernandes I thought polysio did not need air gap and could be placed directly on roof. My main concern is stopping condensation drips in the winter from propane heat. maybe I could make spacers and small air gap.

freenez2 not sure what will attach with. I looked at double sided tape and all I found was only rated to 105 degree and thought it may not stick in summer heat. So may still use combination of tape, permatex and wood strips.
Any other advice would be much appreciated as I want to install now.
Thanks
A SEEKER

I believe if you place the foil side up against the roof it will conduct heat. Almost any material in contact with a heat source will absorb heat. The van metal roof can get pretty warm in the summer.
I wish I had followed in the advise I'm giving you. Not that I've had much of a problem yet. In the summer the van got pretty warm at times, but after opening the windows and/or doors for a while it was very bearably to sleep in it.
If I was doing it again I would cut little pieces of the pink foam I used and used them as spacers for the Reflectix. I guess you could do the same with Polyisio.
3m makes high temp vhb double sided tape. I forget what the rating was but I think it was around 300 degrees. btw if you use that it would give you a small air gap. highdesertranger
If you go to the Home Depot page you linked to, Scroll down until you find the Product Overview. To the right of thst you will find a box that says "Info & Guides". Inside that box, like on most product pages on Home Depot's website, you will find installaion instructions (pdf download).

Radiant barriers and reflective insulation systems work by reducing radiant heat gain. To be effective, the reflective surface must face an air space. If you insist on it facing the metal skin of your vehicle, then you need to allow at least a 1/8" air space (best provided by a layer of bubblewrap packing material). For mobile applications, I would suggest that you face the barrier towards your living space. Use an adhesive made specifically for "foamboard" (you can find it in the Paint Dept at Home Depot). Other adhesives will dissolve the foamboard. And then it falls off the wall or ceiling, usually at the worst possible time.
highdesertranger, I just watched a lot of videos about the 3M VHB tape. That is some very good tape. It has high strength and can even be used instead of rivets. It's being used in so many applications . . . like holding the outside panels on cargo trailers.

Great find hope its not too expensive.
Thanks
A SEEKER
I bought mine from Outwater.com but Amazon has it too. Watch the shipping charges.

Back when I bought mine, it was a little hard to find. Clean surfaces with rubbing alcohol before sticking and make sure it is exactly where you want it, otherwise you will need to change your mind as to where you want it. I put Reflectix backed vinyl up on our pop-up camper walls using the VHB tape to secure the reflectix to the walls.