# Can I Use Foam Board Beneath My Radiant Barrier On Rafters



## joecaption (Nov 30, 2011)

If this a finished attic, or just an empty space?
I'd be far more concerned with air sealing, making sure there's soffit vents that are not blocked with insulation.
And enough insulation in the joist area.
http://www.energystar.gov/index.cfm?c=home_sealing.hm_improvement_insulation_table


----------



## MorknMindy (Jun 15, 2012)

Sorry joecaption I`ve been at work the past few days. Yes, it is an unfinished area. Roof peaks are almost 6' from the ceiling joists. Looking out from the inside first rafters, then purlins, then plywood deck, then tar paper and shingles. I have been putting pieces of foam board out near the eaves to prevent the insulation from blocking the eave vents to make sure I`m getting plenty of air to the ridge vent. I am doing a little at a time as the heat up there allows.

I have friends in newer homes with radiant barrier who say it is helping keep their attics a lot cooler so I am going to do that but thought the foam board between rafters would help as well.

Thanks for your reply.


----------



## Gary in WA (Mar 11, 2009)

Radiant would work for your location. 

Is the HVAC in the attic?

Is the attic floor insulated already? How/what much?

Gary


----------



## MorknMindy (Jun 15, 2012)

Gary in WA, Thanks for the reply. Yes my A/C evaporator/furnace is in the attic and the attic has insulation blown to six inch depth.

So to recap

My roof underside is unfinished and purlins are on top of rafters. Here is where I will put a radiant barrier.
6" blown insulation throughout.
Ridge vents.
A/C -furnace in attic.


I am home for a few days now and will check back. Thanks.


----------

