Vinyl backed insulation vs blown in

[DCarr2]

I can get vinyl backed insulation, 4x50' for around $100....

or those cubes of blown in insulation for $12 a cube...

by the way this is for my attic in my house... currently has 6" fiberglass between the ceiling joists...

I am geussing arouns 120ish cubers to do my attic... or... 16 or so of the 4x50...

yes or no?

ill double check but I think the vinyl stuff is R29

Should I even bother with that foil reflective stuff on the underside of the roof?

 

[NUTTSGT]

Watch which way you put the vapor barrier and you don't really want to double up on it. If you already have fiberglass in the ceiling joists, you can add some unfaced rolls across the joist perpendicular to them.

 

[DC73]

Should I even bother with that foil reflective stuff on the underside of the roof?

Radiant barriers are rarely cost effective if you've already properly insulated and properly air sealed. IF you can get the material for free or very low cost and IF you can do the work yourself, it might be worth it in the long run.

But, your best bang for the buck is to air seal and insulate first.

DC

 

[Firebrick43]

A big no to the vinyl backed insulation. You should only put unfaced insulation over and existing layer.

The cellulose will perform better anyways.

Are you sure cellulose is 12$ a cube?

It's less than 7$ a cube here.

 

[Bamafan]

My advice is slightly different:

1) Oak Ridge Labs did a study on radiant barriers. They can be effective in hot climates. Not where you are.

2) Use blown-in fiberglass. Cellulose insulation is very heavy (about 2x the weight of fiberglass for R30) and will compress the insulation you already have in place, rendering it much less effective. It is also much less dusty to install.

 

[Radix2]

My advice is slightly different:

1) Oak Ridge Labs did a study on radiant barriers. They can be effective in hot climates. Not where you are.

2) Use blown-in fiberglass. Cellulose insulation is very heavy (about 2x the weight of fiberglass for R30) and will compress the insulation you already have in place, rendering it much less effective. It is also much less dusty to install.

The new studies show that Fiberglas is not as effective as cellulose in cold climates due to air movement through the material. The old Fiberglas is not very effective anyway, add new cellulose sufficient to get to your R target, the air barrier of the cellulose on the Fiberglas will likely make up for any compression IMO.

Big no to the plastic wrapped stuff.

 

[DCarr2]

A big no to the vinyl backed insulation. You should only put unfaced insulation over and existing layer.

The cellulose will perform better anyways.

Are you sure cellulose is 12$ a cube?

It's less than 7$ a cube here.

http://www.homedepot.com/p/GreenFib...w-in-Insulation-19-lbs-Bag-INS541LD/100318635

If I buy $100 or more at once its $8.50 a cube. otherwise $12 a cube. While more money spreads out the cost over time into something more manageable

 

[DC73]

1) Oak Ridge Labs did a study on radiant barriers. They can be effective in hot climates. Not where you are.

Radiant barriers do work. They are rarely cost effective. The Oak Ridge study only used R13 fiberglass insulation and no air sealing. Once you get proper amounts of insulation and proper air sealing, the additional heat gain stopped by the radiant barrier is generally not cost effective, especially when paying a contractor to do it. A low cost or no cost option is generally the best way to go when installing radiant barriers.

The study should have used a properly insulated (code minimum) and air sealed attic to start with. Then, they should have compared the cost of the radiant barrier to additional insulation.

DC

 

[unlvrebel]

I put unfaced batts in my attic. BRUTAL work. Use the blown in. Much easier and just as effective.

 

[Firebrick43]

http://www.homedepot.com/p/GreenFib...w-in-Insulation-19-lbs-Bag-INS541LD/100318635

If I buy $100 or more at once its $8.50 a cube. otherwise $12 a cube. While more money spreads out the cost over time into something more manageable

Blow in insulation isn't something you do a little here or there over time. Most of the time you have to buy a certain amount to get the blower for 8 hours. Actual blow time would be only 2 or 3 hours. Breaking apart a cube and raking it out by hand does not work for anything but the smallest of spaces.

Also have an insulation contractor quote it. Many times their quotes installed are cheaper than what you can buy materials for and you don't have to fool with it.

 

[rburke65]

I figured my rolls of insulation, trips to get them home, staples, bales, rental of the machine, my time.... I called a local insulation contractor and the difference was $100. I couldn't write that check quick enough.