# Do I Need Attic Insulation?



## Carbo (Jul 31, 2005)

The reason I ask is because I live in south Florida. Obviously, heat loss isn't the issue. And since the concern here is keeping cool, and cool air falls, what benefit does attic insulation offer?
The house is 20 years old, with existing insulation of about three to four inches of what appears to be blown in cellulose. 
What got me to thinking of all this is the pending installation of a new central AC system. I figure if I'm dropping $5K, I ought to do my best to keep the cool air where it belongs.
So, what do you think? Add some insulation up there? I've been quoted $400 by a local company for six inches of blown in fiberglass, (approx. 1,400 square foot attic). I realize it won't hurt anything, but will it help keep the house *cool*?


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## housedocs (Mar 14, 2005)

Insulation works by maintaining a climate controlled within the dwelling. Insulating the ceilings makes sense regardless of location. Certainly wouldn't need as much as someone in the midwest or northern part of the country. Here's a link that will answer all of your questions about home insulation, hope it helps.
http://www.ornl.gov/sci/roofs+walls/insulation/ins_16.html


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## Sportbilly (Jul 31, 2005)

Ever been in an attic in the summer?

There's your answer right there, even though convection doesn't aid in the heating of a room via the ceiling, the amount of heat present in an attic, generated by the sun beating on the roof deck, is huge. Some of it will end up in your living area.


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## Carbo (Jul 31, 2005)

OK. Insulation is probably a good idea, then. But that leads to a bigger question, I suppose. With attic temps hitting 130 degrees in my neck of the woods, venting it becomes an even greater issue.
I've got a new roof planned a few months down the road. Which would be the appropriate time to get an attic venting system in place. Currently, other than soffit vents, there aren't any. I see new roofs in my neighborhood, and it seems the latest rage is the ridge vents. Pros and cons?
And what about either a turbine vent, or an attic fan? I read that attic fans are actually a bad idea, because they are so effective at sucking out the air, they will go so far as to pull out the air conditioned air from the house. Any validity to this theory?
Thanks, folks!


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## Teetorbilt (Feb 7, 2004)

Carbo, I'm just north of Palm Beach. I had a new Trane system installed last year, got $1K off and 6 mos. same as cash, pretty good deal. This year I had the old dark shingles replaced with metal roofing and a radient barrier put underneath it. I have ridge/soffit vents plus gable end vents. Over the last few months, my electrical usage has gone down 36-37%, pretty good. Unfortunately, I pretty much did this all at once so I cannot tell you which one had the greatest impact.

Insulation slows heat from travelling from one place to another. More is usually better. I have the standard fiberglass mat over the ceilings and have decked over much of it for storage space. If I were to add more, I would use the blown in cellulose. Whatever you use, make sure that the soffit vents aren't covered in the process. I haven't actually taken temp. readings up there but I can assure you that it's a lot cooler than it used to be.


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## housedocs (Mar 14, 2005)

Teetorbilt said:


> Carbo, I'm just north of Palm Beach. I had a new Trane system installed last year, got $1K off and 6 mos. same as cash, pretty good deal. This year I had the old dark shingles replaced with metal roofing and a radient barrier put underneath it. I have ridge/soffit vents plus gable end vents. Over the last few months, my electrical usage has gone down 36-37%, pretty good. Unfortunately, I pretty much did this all at once so I cannot tell you which one had the greatest impact.
> 
> Insulation slows heat from travelling from one place to another. More is usually better. I have the standard fiberglass mat over the ceilings and have decked over much of it for storage space. If I were to add more, I would use the blown in cellulose. Whatever you use, make sure that the soffit vents aren't covered in the process. I haven't actually taken temp. readings up there but I can assure you that it's a lot cooler than it used to be.


Teetor,

Curiousity question, radiant barriers aren't something you see much of here in the mid-west, but many yrs ago in Tx I was doing what were called attic wraps for a sub contractor for Sears siding. This consisted of stapling a sheet over the underside of the trusses/rafters. The sheeting was like a brown paper on the one side & aluminum foil on the other, stapled the foil side towards the roof, always figured those roofs would need to be redone with a yr or two. I only worked for this guy about 2 mos before moving on, so I don't know that to be a fact. So what exactly are they putting under the roof as a radiant barrier? In these parts only thing I've ever put under a metal roof is sheet styrofoam insulation.


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## Carbo (Jul 31, 2005)

Teetorbilt said:


> Carbo, I'm just north of Palm Beach. I had a new Trane system installed last year, got $1K off and 6 mos. same as cash, pretty good deal. This year I had the old dark shingles replaced with metal roofing and a radient barrier put underneath it. I have ridge/soffit vents plus gable end vents. Over the last few months, my electrical usage has gone down 36-37%, pretty good. Unfortunately, I pretty much did this all at once so I cannot tell you which one had the greatest impact.
> 
> Insulation slows heat from travelling from one place to another. More is usually better. I have the standard fiberglass mat over the ceilings and have decked over much of it for storage space. If I were to add more, I would use the blown in cellulose. Whatever you use, make sure that the soffit vents aren't covered in the process. I haven't actually taken temp. readings up there but I can assure you that it's a lot cooler than it used to be.


Teetorbilt, thanks for the reply. I'm also looking at a Trane high efficiency system. They have the 19 SEER, and the 16. I'm not sure which I'll be going with yet, but I'm sure either will be a big improvement over the old clunker I'm running now. Just waiting for the Trane rebate program to begin anew, (September 1). $1,000 back is worth the month's wait.
As for a roof, I'm looking to do a strip and replace in the Fall. Asphalt shingle, and probably using a ridge vent. I'll ask around to get some feedback on the radient barrier you mentioned. Hadn't thought of that. It could be beneficial. What can you tell us about your's? All of that, combined with having six inches of blown in insulation put down, should make the attic a bit more comfortable.


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## Neil_K (Oct 30, 2004)

Hey Housedocs, the aluminum foil stuff reflects radiant heat. Works best with the ridge vent, as it channels the hot air between the back of the roof and the reflective material. afs-foil.com gives a better explanation. I am not endorsing their product, but have looked at products like it for my attic. You can buy the stuff at Lowes or HD and do it yourself.


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## Teetorbilt (Feb 7, 2004)

housedocs, anything that reflects heat in the south is worthwhile. Radient barriors are best placed over the roof deck, stop the heat before it can get in. Once inside, you have to get rid of it somewhere.

Carbo, Oil today was $68.00 a barre. I don't see the price growing smaller. Last year, I would have said be moderate (which is what I did). This year, I would max the wallet. I don't see any reversal coming soon. I'm also looking at downsizing some vehicles and raising certain figures, I can't be expected to bear the brunt of this.

Neil, if you happen to be in a hurricane zone you may want to reconsider ridge vents.


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## toolmanwannabe (Sep 16, 2005)

I just began laying insulation in my attic and have screwed some plywood down for storage space. the attic had a few inches of blown fluff insulation but I bought the rolled (10" thick) thinking it is more effective. Is it?

I used a broom to move the fluff insulation out of the spaces where I layed the rolled insulation. I figure if I lay rolled insulation where I'm finishing the floor (about half the attic space), I'll have a lot of fluff that I can layer up (on top of existing fluff) on the unfinished areas. Is this an effective stategy or should I buy enough rolled insulation for the whole attic space?

Also, does insulating and finishing an attic count as an energy efficient home improvement that qualifies for tax credits?


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