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Full Version: Polysio strips for air gap. Might this work?
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I finally received my 3m VHD tape. I cut out these strips of Polysio and taped to the roof. I am going to start with 1/2 inch Polysio with foil side up as in the photo. Then I will add another layer of 3/4 Polysio to that with foil side facing inside.

Do you think this is good way to do it? It creates a lot of air space maybe too much. Advice please.
A SEEKER
I would use plain old packing bubble wrap as a spacer. It would provide continous supportand maintain the space consistently.
I don't think you need any air gap with polyiso or styrofoam. It's not reflectix which requires the air gap.

I just flush mounted the sheets of insulation against the sheet metal of the vehicle and sealed it with Nashaua foil tape.

The results were better than I had hoped and I noticed a large reduction in the amount of heat that could pass the sides of the van.

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Right, Polyiso doesn't need an air space. It doesn't hurt, and it might even help very slightly, but it isn't necessary.
Bob
HEAT BARRIERS (you know, that shiny metallic looking stuff on particular types of polyiso and on Reflectix) requires an air space to work right. So with an air space next to the skin, you can put the heat barrier (shiny side) towards the skin/air space. Without the airspace, you need to face the heat barrier (shiny side) towards the interior living space.
Guess I will still use the spacer strips of polysio on the roof as it evens out the roof making the first layer anchor better. That is unless I find too much loss of head space by the time I add the other layers.

66788, What is the shiny layer on your wall? Something covering your insulation? Which Nashua tape did you use? The cold weather?

Compassrose, I will be incorporating some bubble wrap also but want some stronger anchor points too because of fear bubble wrap may let go with age.

highdesertranger, Thanks for the info about the 3M VHB tape. I ended up with the 4991 and it has amazing hold although expensive. it's rated for short term up to 250 degrees and long term to 200.

Bob, Thanks for response and quick email last night.
A SEEKER
you are very welcome. I have used it to stick various things and if you want to remove what ever you installed you might destroy it. higdesertranger
Anchor points for the ceiling? You could try what I did. Furring strips carefully screwed into the roof beams. Then double sided tape on the strips.
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(11-09-2014, 11:10 PM)compassrose Wrote: [ -> ]HEAT BARRIERS (you know, that shiny metallic looking stuff on particular types of polyiso and on Reflectix) requires an air space to work right. So with an air space next to the skin, you can put the heat barrier (shiny side) towards the skin/air space. Without the airspace, you need to face the heat barrier (shiny side) towards the interior living space.

This PDF backs up the air space benefit for a foil sided rigid insulation (with foil facing to the air space). It adds about R-3 to 1in thick sheet (R4.3 to R7.2).
thanks adi for that link. highdesertranger