Attic film, reflective foil film?

[JohnB]

I just heard about some foil you can lay down on top of attic insulating and reduce the cooling costs of a home in the summer. Anyone look into this, use this, any opinions?

John

[Mr_Tom]

John,

When I first moved into my home, I had to add insulation to my attic. The previous insulation was damaged by previously stored items, and seemed to settled down. When I researched it, I found the back R required by building codes is far less than the department of energy's recommended R (if memory serves me). I went on a insulation information hunt. I found how I could install more, I choose batts of fiberglass, without a vapor barrier. Since it it was a DIY project, and I could buy one bag at a time. Over time, I got a lot of insulation in my attic. Then with rise of energy, I looked into other ways to save energy. I saw this film stuff. I found out that because I went with a 24/7 energy approach(insulation works both during heating and cooling season), I could see very-little to no return on the film product. I figured any product that relies on me to have already poor insulation, only works during one season, was not worth my money.

Tom

[NJHandyMan]

Over the insulation? Are you sure it's not in the roof rafters? Any 'film' over the normal insulation might be a trap for moisture. Once the insulation get's wet it's insulation values drop, and might lead towards a bug/vermin problem.

I'll have to look into this.

NJ Handy Man

[JohnB]

The film is said to be perforated to prevent moisture entrapment.

John

[NJHandyMan]

OK, so it's hot holes to prevent moisture entrapment. Have to say, this might sound good on paper, but in the real world any delay in water escaping the insulating can result in condensation.

Just thinking about the pros and cons of this reflective barrier material.

NJ Handy Man

[Mr_Tom]

I have a lot insulation in my attic. Something like R70. The original layer is blown in fiberglass loose fill, then an R30 batt, then another R30 batt. Adding insulation has taken time since with each batt I've removed the paper vapor barrier prior to laying down. I was told just cutting quick holes in the paper, like alternating lashes defeats the vapor barrier, but I don't trust it. Like you said, any delay in moisture trying to escape the insulation could be a condensation problem. I do not have a separate vapor barrier in my attic, no ploy film. So I've been concerned about moisture in my attic insulation.

Tom

[NJHandyMan]

So you peeled off all those vapor barriers. I"m guessing two things, you were using insulation with kraft paper and you were itching like crazy when you were done.

Attic insulation tip, try to get unkrafted insulation.

NJ Handy Man

[Mr_Tom]

Oh yeah, I was itchy. I still have a few spots I want to fix, so I will be backup into the attic soon. Weather is cooler, so attic work is easier. I go to Lowe's for many of my building materials and do it yourself solutions, so they do not have unkrafted insulation.

Oh back on to this attic film stuff, I have seen stuff that is installed under the roof sheathing. It has channels that direct heated hair from under the sheathing right up to the ridge vent. I thought that was cool, but didn't look like an easy way to retro fit an existing attic.

One more note, the weather is becoming such that working in the attic is OK. It would seem like the best time is to wait till winter, but an open attic hatch or door will allow any heating saving go right up there. So fall and spring are the best times, when you aren't using AC or heat.

Good luck, and get busy.

Tom

[mrSparkie]

Funny how this reflective foil insulation keeps coming out when ever there is a problem with oil prices going up. I have to stand with the common sense approach. If heat is going through your insulation, then you don't have enough. That is it, rather than trying to install reflective foil insulation in your attic, get some more insulation up there. This way it will work 24/7, not just in the sunny days, and it also works as a sound damping barrier to help keep the home quieter.

Mr. Sparkie