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Community and Q&A

Radiant barrier OSB help needed

Roger_S39 | Posted in General Questions on

Hi all,

Wondering if it would be worth it to upgrade to a radiant barrier roof deck for the following scenario?

– Vented, unconditioned, attic.
– Hvac equipment located in attic (Furnace, erv, duct lines)
– Zone 4a North West Arkansas


1). Would the radiant barrier reduce attic temperatures enough to extend the life of the hvac equipment?

2). Would people prefer to have a 7/16 radiant barrier roof deck or a true 1/2″ OSB non radiant barrier roof deck – for the above scenario?

Essentially, wondering if $$$ is better spent on a thinner OSB radiant barrier roof deck or a thicker NON radiant barrier roof deck.

Thank you for the replies in advance.

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  1. Expert Member
    Dana Dorsett | | #1

    In order:

    1) NO! It would modestly improve the net efficiency, but would have very little impact on the lifecycle of the equipment.

    2) In many local jurisdictions (and maybe yours), structural roof decks required to be at least 5/8". But if you're not going thick and won't reconsider putting the equipment in vented unconditioned attic, go with the RB sheathing.

    But the real problem is the whole notion of putting the equipment outside the thermal and pressure boundary of the house, adding to the heating & cooling loads in multiple ways.

    The upgrade worth paying for is bringing the ducts & air handler inside the pressure and thermal boundary of the house, and it's much cheaper to do during the design phase than later on. It will always more comfortable and not necessarily more expensive to right-size keep it all fully indoors and right-size it by design. Most systems that get jammed into a vented attic end up with ridiculous oversizing factors that while it will heat & cool the house while provides limited comfort, and not always enough comfort to all rooms.

    How far along is this house design? Any preliminary heating & cooling load numbers?

    These pages & videos put up by Nate Adams (who works primarily on fixing problems after the fact) are worth a review as you ponder the options:

    It's much cheaper and better to get it right the first time than it is to try to make it work after the fact.

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