Rigid Roof Insulation Weight

[Boiler106]

ASCE states that rigid roof insulation weighs 1.5 psf per inch of thickness, whereas, polyiso insulation, like Thermax, is < 0.25psf per inch.

Is there a reason why ASCE might be so much heavier? Is it assuming some sort of saturation?

 

[spieng89]

ASCE tabulated weight values are known to be conservative, if you can justify a lesser weight with documentation and you need that extra weight savings then feel free to do so

 

[SlideRuleEra]

ASCE is probably referring to older wood fiberboard roof insulation.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[dik]

or just a catch all for any rigid roof insulation.

Dik

 

[XR250]

Maybe once the membrane is shot, they assume it absorbs water :>

 

[P205]

I'm looking into this at the moment and stumbled across this thread.

I have no problem using the catch-all value for normal gravity design, my issue is with the wind uplift, you would want to use a more accurate value.

 

[IRstuff]

Wood shake roofing comes in around 4 psf wet, and 1.5 psf dry.

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[DETstru]

The ASCE number is way off compared to what is typically used for rigid insulation. Use a value based on whatever product they're specifying.

 

[Ron]

The 1.5 psf/in is consistent with lightweight insulating concrete. Rigid board insulation is much lighter.