Which one?

[txstangnut]

Foam or Radient barrier for the attic?

[STRONGNUFF]

I heard that the radiant barrier is not as efficent as they claim. Now foam on the other hand I can tell you when they were building some new homes the next block over, my wife and I walked them as they were still being built.

They used the foam in the attics and in all the outside walls and the attic was roughly 10* cooler than the outside temp of mid 90's which I was amazed with considering that none of the sheetrock had been put up yet. We plan on getting our attic's done with foam and will post up before and after pics and results when done.

[8mpg]

Foam is good stuff. Saw a couple demo setups at Kelidoscope of Homes this year and it was a good 10* different.

[KBScobravert]

Are they just using 4'x8' sheets of 1/4" foam?

I have a huge f'ing roof line and would love to do a partial inclose of the attic above the garage. It won't be complete if it is 100*+ up there in the dead of summer.

[STRONGNUFF]

Are they just using 4'x8' sheets of 1/4" foam?

I have a huge f'ing roof line and would love to do a partial inclose of the attic above the garage. It won't be complete if it is 100*+ up there in the dead of summer.

They actually blow in the foam, its the kind that expands on contact to fill all the nooks etc. Roughly 10"-12" thick on attic roof

[bard]

New construction or retrofit? If new and you can swing it, enclosing the entire home in spray foam is pretty cool. I toured this home a few years ago that used it and the attic temp wasn't much warmer than the living area. Of course there isn't any insulation between the attic and the living space so there shouldn't be. My only concerns are about roof leaks. How does this stuff deal with water and how much damage will be done before you realize there is a leak? Spray foam doesn't have a high R factor, so it's main purpose is sealing the gaps to stop air infiltration. Radiant barrier backed roof decking works quite well and will be your best choice in my opinion for a retrofit. I have it in my home with just passive ventilation and it's much cooler up there than my previous home which had the RB paint applied. The paint helps, but not as well as the RB decking.

[Chili]

Yeah, from watching all of the diy and home improvement shows the spray in foam is the best.. Not sure about the difference in price points though.

[KBScobravert]

They actually blow in the foam, its the kind that expands on contact to fill all the nooks etc. Roughly 10"-12" thick on attic roof

thanks Andre, oh and the $100 fridge is still kicking in the garage as a great beer cooler.

I am not going to go through the expense of spray in but I do something this time home if I have the time

[KBScobravert]

New construction or retrofit? If new and you can swing it, enclosing the entire home in spray foam is pretty cool. I toured this home a few years ago that used it and the attic temp wasn't much warmer than the living area. Of course there isn't any insulation between the attic and the living space so there shouldn't be. My only concerns are about roof leaks. How does this stuff deal with water and how much damage will be done before you realize there is a leak? Spray foam doesn't have a high R factor, so it's main purpose is sealing the gaps to stop air infiltration. Radiant barrier backed roof decking works quite well and will be your best choice in my opinion for a retrofit. I have it in my home with just passive ventilation and it's much cooler up there than my previous home which had the RB paint applied. The paint helps, but not as well as the RB decking.

I was talking it over with some folks at work (bored) and they were saying that if I insulated the roof decking it would not breath and defeat the soffet vents. I am no roofing expert but it did make sense. I would also be worried about water damage too. How long would it go on before you realized it.

[Alvarado GT]

Are they just using 4'x8' sheets of 1/4" foam?

I have a huge f'ing roof line and would love to do a partial inclose of the attic above the garage. It won't be complete if it is 100*+ up there in the dead of summer.

Has anyone done this? You would think that it would help out, just not sure how much. It should be an easy install too. I would think that you could just cut it to fit between the trusses and stick it to the roofing nails that come through the roof, maybe a little liquid nails on the backside

[STRONGNUFF]

thanks Andre, oh and the $100 fridge is still kicking in the garage as a great beer cooler.

I am not going to go through the expense of spray in but I do something this time home if I have the time

Glad to hear about the Fridge, didnt recognize the s/n here

[bard]

I was talking it over with some folks at work (bored) and they were saying that if I insulated the roof decking it would not breath and defeat the soffet vents. I am no roofing expert but it did make sense. I would also be worried about water damage too. How long would it go on before you realized it.

The way they did it at the Bannister house (link I posted earlier), they draped Tyvek type sheeting and let it hang low between the rafters. That provided the gap for air flow.

[txstangnut]

mine would be a retro fit. I kinda had the same concerns about water and air flow.

[BlackSnake]

I dont know anything about the foam, but most of the Radient Barriers are nothing more than snake oil. A good radiant barrier is actually a two part. The silver is like a powder and you add the activator to it. This really works, but dont expect a 100 dollar a month change. The stuff the paint stores and Home Depot sell is crap.