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| Any experience/opinions using aluminum insulation over existing insulation in attic? We were quoted at $1.75 per sq ft (around $2400 before tax rebate) and is suppose to reduce utility bills 30%. Specifically it is 2 faced perforated aluminum insulation. |
Follow-Up Postings:
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- Posted by sierraeast (My Page) on Thu, Jan 21, 10 at 10:29
| Are you referring to radiant barrier? Some are foil faced with a kraft paper backing and fiberous mesh inbetween, others are foil faced both sides, and some are perforated while others aren't. |
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| Radient barriers work well, but roofing materials have to be suitable for their use. The barriers make the roof a lot hotter and can degrade asphalt shingles much more quickly. |
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- Posted by sierraeast (My Page) on Thu, Jan 21, 10 at 17:50
| Hi Handy, That's true when using techshield plywood as sheathing, but installed properly on the underside of the rafters with a continous run ridgeventing/soffitventing allows the heated air to escape on out the ridge. The radiant barrier traps the heated air between the roof sheathing and the space below the rafters,( in the rafter cavatie). As long as their is an avenue of escape for the heated air, it wont effect the shingles. I believe what the o.p. is referring to as far as installation, is laying the radiant down horizontally over the insulation/joists, which is another install method. Some radiant barrier outfits will tell you the latter install method is ineffective due to dusts building up on the product, while others state that dusts have no effect whatsoever. |
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| Correct, the barrier would be placed horizontally on top of the ceiling joists and above the existing batt insulation. The ultimate question is whether it makes sense to pay $2400 for the radiant barrier or spend the same amount or less on more typical (blown in) insulation? The attic is approx 1300 sqft. What would give the most bang for the buck? Thanks for the feedback. |
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- Posted by sierraeast (My Page) on Thu, Jan 21, 10 at 21:26
| Are you fairly handy as this is a pretty straight forward install concerning radiant barrier or blown in cellulose. With blown in, many places will let you use the blower if you buy the cellulose from them, or you can rent the blower. The radiant barrier typically comes in 50" width rolls where you overlap 2" for a 16" on center layout. The amount of rolls dependent on sq.footage of the project. You could save the labor doing either project d.i.y. as long as you still qualify for the tax rebate going this route. |
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- Posted by energy_rater_la (My Page) on Fri, Jan 22, 10 at 0:07
| radiant barriers raise temps 2 to 3 degrees not enough to shorten shingle life or void warrenty. the correct install is to install rb on the undersides of when laid on attic flooring the reflectivity is reduced by dust buildup and within a very few years becomes useless. by placing the foil on the attic floor you are allowing there is no 30% savings.. visit www.buildingscience.com and search for radiant barrier info I diy'd my radiant barrier..about 9 hours to do best of luck. |
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| This is actually for my parents in Iowa. Primary reason is to reduce heating bills. Sounds like the double sided perferated aluminum foil helps mainly in summer months, but may not help as much keeping the house warm during winter? |
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- Posted by energy_rater_la (My Page) on Fri, Jan 22, 10 at 20:44
| http://www.fsec.ucf.edu/en/publications/html/FSEC-EN-15/index.htm#payb
ack there are better efficiency upgrades for your parent's location. this isn't one of them. these rb pkgs are often sold to older people who buy into the ease of saving from the link: Can't I just roll the material out on top of the insulation? Will heat build up in the roof and damage my shingles? best of luck |
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