# SoCal attic insulation recommendations



## 1psadler (Jan 3, 2016)

I hope this is not too long, but this is my first post here and wanted to give some background. My home is an Orange County, Souther California 1950s, raised foundation, stucco, hip roof, two bed, one bath, 900 sq ft. For cooling I temporarily install a window air conditioner in the summer. The floor furnace does not work. The disintegrating burner can’t hold a flame, so we use oil filled space heaters. Not the best solution but it works for now. Summers can be very hot for a few weeks and winters are generally mild, rarely freezing. Our preference is to install radiant floor heating at some point in the future, and further develop passive cooling solutions.

But first on our list is insulating the attic. The are a few soffits at the eaves, small gables at either end of the attic and a turbin fan at the center of the roof. We would like to remove the old batting and clean out the attic prior to new insulation. Solar gain from the roof is a concern. 

My current thinking is to install a foil radiant barrier on the attic ceiling and two layers of fiberglass batting on the attic floor. But then I read all the pros and cons of foil radiant barriers, versus the wonders of closed cell foam and it all gets blurry. What is the preferred plan for insulating this particular attic?


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## ddawg16 (Aug 15, 2011)

Your house sounds just like mine.

You have blown-in insulation in the ceiling and NOTHING in the walls. All the houses built around that time were the same. I'm betting your floor heater is sandwiched between the 'living room' and hallway....

Solid oak floors? 

Insulation is no fun. And to be honest, you don't save a lot of money doing it yourself.

I just had my floor insulated last week. 1027 sq ft....R19 between the floor joists....cost me $792. Best $792 dollar check I wrote. Made a big difference. 

If I may suggest....call and get some estimates. Personally, I like KBH Insulation out of El Segundo. They did my addition and my floor. I referred them to friends who were also happy. 

This is one of those tasks where it is just easier to farm out.

On your walls.....ask....they may have an option.

But also look at your windows.

And while you are at it....consider going with a forced air heater in the attic. I have a 60K BTU system and it does a fine job of heating my whole house (including addition). Because I'm well insulated, even with the cold nights and the setback at 62 deg, the heat does not come on...only once have I gotten to 62. At 6am it comes on for 20 min.....then about a 10 min pause, and then about 10 min more to stabilize the temp at 70. Then it might come on one more time until it sets back to 62 at 8am.


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## 1psadler (Jan 3, 2016)

Hey ddawg16. Your house does sound like mine for sure, down to the oak flooring and old furnace. I've already changed all the windows and I'm designing on a bath remodel. What type of insulation did you install? It sounds like it has been very effective.


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## ddawg16 (Aug 15, 2011)

On the floor, unfaced batts between the joists.

Attic....faced batts. 

I'd let the insulation company suggest what is best.

Is your bathroom by any chance a bathtub with a separate shower?


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## Gary in WA (Mar 11, 2009)

Welcome to the forum!

Glad the attic is first on your list. As you are here at DIY, we presume you want to do it yourself... much better job can be had if you pay attention to the details. R-19 is the least effective insulation for attic/walls because it is a "low-density" insulation inherent with convective loops after even a perfect installation because of the air moving through it removing your heat; http://www.diychatroom.com/f98/biggest-loser-fiberglass-insulation-90438/

R-13 is a medium density- 0.76# per cubic foot, R-15= 1.41# (high density), R-19=0.44 (low density). Because of the wood joists exposed to attic temps, they act as thermal bridges, though not as bad as steel does; http://buildingscience.com/documents/insights/bsi-005-a-bridge-too-far?searchterm=steel+studs 

Then the colder incoming attic air permeates (top few inches) of the low density junk to drop the temps there to outside air temps, bringing the proximity of the delta even closer because now the thickness of your thermal barrier is reduced-- you get the picture. At least cover the batts with a layer of cellulose (or a house wrap) or even fiberglass blown-in to cover the thermal losses of using batts in an attic in the first place; Photo 2; http://buildingscience.com/documents/insights/bsi-060-joe-south-assemblies

Air seal the attic after removing existing insulation, add the radiant barrier (good for your location), increase the attic ventilation to a 50/50 of high/low vents, wrap/VB any ducting to get moneys worth. Have links if needed...

Gary


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## 1psadler (Jan 3, 2016)

Thanks for the detailed reply Gary. When you say air seal the attic I think you mean the attic floor and any air leakage around light boxes, and the like? I think a layers of R-15 between the joists, and a cross layer on top of the joist would be effective on the attic floor reducing the thermal bridge noted.

The bath was originally an alcove tub/shower. It was made into a large shower. I'm returning to the tub/shower combo.


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## Gary in WA (Mar 11, 2009)

Yes, all holes from wires/pipes, chases around flues, drop-ceilings, with the appropriate rated foam/metal; http://www.google.com/url?sa=t&source=web&cd=23&ved=0CCUQFjACOBQ&url=http%3A%2F%2Fapps1.eere.energy.gov%2Fbuildings%2Fpublications%2Fpdfs%2Fbuilding_america%2Fba_airsealing_report.pdf&rct=j&q=foam%20board%20in%20attic%20require%20thermal%20barrier%20with%20drywall%20already%20installed%20on%20other%20side%20of%20kneewall&ei=IvqWTveuIKW0sQK3zPzwBA&usg=AFQjCNHwd56o0AxLi8-V03E5cMUmwWATQw&cad=rja

Then, to relax your legs from carefully walking the joists, air seal the crawlspace of any holes in the floor above to stop the stack effect; http://www.wag-aic.org/1999/WAG_99_baker.pdf
Sounds good R-15 twice, only better would be a layer of cellulose or SPF $$$$$, lol.http://www.ecologices.com/savings-e...s-thermal-bridging-through-studs-and-rafters/ The cellulose or housewrap stops the c- loops.

Gary


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