Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > Insulation

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Search this Thread Display Modes
Old 01-30-2013, 04:59 PM   #1
Newbie
 
Join Date: Jun 2012
Location: Texas Gulf Coast
Posts: 21
Share |
Default

Can I Use Foam Board Beneath My Radiant Barrier On Rafters


I want to apply a radiant barrier to a 70`s ranch style with a conventional built roof frame...(no trusses). I live on the Gulf Coast area 2 and it is 30-100 here at times of the year. It is very humid about 8 months a year and from past reading I have learned that insulation between the ceiling joists is recommended to be installed without backing. So okay.

The roof was originally wood shingles. This means on top of the rafters there are 1x4 purlins about every 12" on center. I had my roof reshingled several years ago and at that time the wood shingles were removed, the purlins left in place and decking applied before asphalt shingles were laid down. My attic is fairly easy to access except to about 3' from the eaves but I can get there.

What I would like to do is apply the radiant barrier in strips between the 2x6 rafters, then say leaving a couple inches between the radiant and a foam board insulation, I would like to apply foam board between the rafters. Does anyone have an idea whether I will substantially reduce heat coming through to the attic if I do this? I have a roof vent that runs along the peak all the way across the roof so ventilation won`t be a problem I don`t think. I don`t intend to make everthing air-tight but was thinking adding foam board will help reduce heat transfer coming from the radiant barrier to attic. Any thoughts? Thanks all for your replies.

MorknMindy

MorknMindy is offline   Reply With Quote
Old 01-30-2013, 06:17 PM   #2
Member
 
Join Date: Nov 2011
Location: Hartfield VA
Posts: 25,743
Default

Can I Use Foam Board Beneath My Radiant Barrier On Rafters


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?...sulation_table

joecaption is offline   Reply With Quote
Old 02-01-2013, 06:37 PM   #3
Newbie
 
Join Date: Jun 2012
Location: Texas Gulf Coast
Posts: 21
Default

Can I Use Foam Board Beneath My Radiant Barrier On Rafters


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.
MorknMindy is offline   Reply With Quote
Old 02-03-2013, 09:33 PM   #4
Registered User
 
Join Date: Mar 2009
Posts: 9,968
Default

Can I Use Foam Board Beneath My Radiant Barrier On Rafters


Radiant would work for your location.

Is the HVAC in the attic?

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

Gary
__________________
If any ads are present in my answer above, I do not condone/support/use the product or services listed, they are there against my permission.
Gary in WA is offline   Reply With Quote
Old 02-14-2013, 01:17 PM   #5
Newbie
 
Join Date: Jun 2012
Location: Texas Gulf Coast
Posts: 21
Default

Can I Use Foam Board Beneath My Radiant Barrier On Rafters


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.
MorknMindy is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Thermal barrier for XPS foam board diyatx Insulation 6 12-10-2012 07:55 AM
Moisture Barrier Behind AND on Top of Cement Board JasonCA Remodeling 0 04-07-2012 01:31 PM
Foam board over old 4in thick fiber board roofing panels Rebob40 Roofing/Siding 2 03-05-2012 09:24 AM
Best adheasive for foam board to concrete BlueBSH Building & Construction 1 08-05-2011 03:06 PM
Installing deck ledger board over foam board? RickT Building & Construction 5 11-06-2006 10:50 PM




Top of Page | View New Posts

Copyright © 2003-2014 Escalate Media. All Rights Reserved.