Insulation value of laminated XPS

[kstills]

Will there be any change in the R value of the XPS once it's sealed with either PMF or Expoxy-Glass? I would think there would be, however I'm sure there's folks here more knowledgeable than I on the subject.

[linuxmanxxx]

Every item has some type of r value so it slightly raises it. We have some extreme heat in Texas and even 3/4"is quite effective in smaller spaces compared to solid wood walls and the same thickness.
Steve

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[kstills]

Every item has some type of r value so it slightly raises it. We have some extreme heat in Texas and even 3/4"is quite effective in smaller spaces compared to solid wood walls and the same thickness.
Steve

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My concern is that by sealing the foam you would lower the R value, since you won't be allowing an exchange of air. I get that there will be 'some' exchange, however what I don't know is how much you need in order to hit the R value that the foam is rated for.

[linuxmanxxx]

As long as you limit pass thru things say like metal or wood things that have inside and outside surfaces with no foam between would lower it. If only outer or inner things exist it doesn't lower.

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[tony.latham]

...since you won't be allowing an exchange of air.

That's one reason insulation works. You want to stop conduction and convection. Moving air is convection.

Tony

[QueticoBill]

Generally, all insulation works better when tightly enclosed and no room ( as little as 1/8") for air to move.