Radiant Barrier in Townhouses

I am a Home Inspector in Phoenix Arizona and have noticed on several, if not all my Townhouse or Condominium Inspections, where the roof sheathing contains the Radiant Barrier, there are always sections that are missing the Radiant Barrier. It’s always in attics that have a firewall or separation between adjoining units above the common wall between the units. I have looked through the building standards and of course the internet and cannot find a reasoning for this. I was hoping someone could shed some light on this.

OK! Please frame you question corrector…
What is your question?

What is the purpose or reason behind the missing radiant barrier, I’ve been told by more than one builder that it is suppose to be that way, but no other reasoning.

Likely the sheathing isn’t rated (listed and labeled) as an approved 2 hour fire separation at the intersection of adjoining attic spaces.

I’d think along with Dominic…if I had to guess. :smile:

Unusual narrative. Radiant Barrie on sheathing. New to me.

Sorry for the edit everyone.

Fire wall/common wall above,between and below the roof decking material, covering and attic space.
Roof deck sheathing requirements.

Dominic is right. What you’re seeing is not radiant barrier, it is fireproofed roof decking. See R302.2.2 in the IRC.

In simple terms: Most roof decking that have the Radiant Barrier (RB) factory installed, is OSB, I’m also going to bet that the decking you see that is exposed is Plywood. I would also say that it would be correct (energy wise) to install an FSK rated Radiant Barrier manually to the Plywood parts at the jobsite or after it is installed…But I’ll bet that the Building/Code Inspector would ball and moan that they could not visually see that Plywood was used for that section of the roof…So that portion is left without the RB and thus wasting energy.

Bryan, are you talking about radiant barrier sheathing (RBS) with the foil barrier bonded to the underside of the sheathing panel?


Based on the original McDowell Owens study. I read the same information from them when it first came out. This may not answer your questions, but it may make you think about what you want to say when you see this product during an inspection.

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