Hey nail pounders and insulation guys - The Hull Truth

baitkiller · 11-07-2007, 02:56 PM

Easy question I hope.

You may remember answering a question some months back regarding joist placement on an addition I'm building.

Well its insulation time and I am here, hat in hand to pose yet more questions.

I don't really need a PHD on insulation but a primer would be helpful.

Here are the particulars:

First, blown in is not an option.........trust me.

Ok stick built 2 story on one end sloping down with rafter to the other. Think right triangle.

The areas I have to insulate are as follows:

6" stud walls
8" stud walls
10" floor joists on 16" centers.....(can I use Tyvek for a vapor barrier over the insulation under the joists?)
12' timber rafters on 20" centers
200 sq.' common truss ceiling.

I need a shopping list. ie: # R19 for X" wall, code #XYZ for 16" spacing etc. Capice?

Thanks,
Your pal,
Spanky

Cat-a-holic · 11-07-2007, 03:04 PM

Is squirted in foam an option?

I just filled the walls of my house with a polyurethane (non-expanding formula) foam which fills the cavity. When applied it has a consistency about like shaving cream, but quickly sets up sort of like styrofoam.

May not be possible if you have constraints that will not allow blown in, but I thought I would mention it.

There is also a sprayed on foam (expanding) which can be used in open areas, and seems to be superior in some ways to fiberglass.

RSV · 11-07-2007, 05:59 PM

Why not call an insulation subcontractor? They can usually provide labor and materials for what you can buy the insulation.
6" is R-19, 8" is R19 (it does no good to shove R30 in 8" wall), 10" is R30, 12" is R38
I don't think Tyvek is vapor barrier but a wind barrier. You can use a 6 mil or 8 mil poly (clear plastic). It comes in sheets and staple to studs. Don't use kraft backed insul and the poly. Vapor barrier always toward conditioned spaces (in floor joists you should not see paper)

boatommy · 11-07-2007, 06:34 PM

Ditto what RSV said. You'll make better wages picking up pop bottles than putting in your own insulation!
thom

Garett · 11-07-2007, 08:51 PM

Quote:

baitkiller - 11/7/2007 4:56 AM

Easy question I hope.

6" stud walls
8" stud walls
10" floor joists on 16" centers.....(can I use Tyvek for a vapor barrier over the insulation under the joists?)
12' timber rafters on 20" centers
200 sq.' common truss ceiling.

Spanky it is not as easy as you'd hope. IMO your comments strike 20 other questions.

For starters, poly always goes on the warm side of the insulation! If one is insulating a floor between two warm floors, no poly is used.

Tyvek to my understanding is not a vapor barrier, Tyvek is a wind and air barrier. Poly is a moisture barrier.

Let’s cut to the chance here with insulation........polyurethane spray foam insulation is the best. Yes it may break the bank, but it will out perform all others hands down! Not only will it be your best R value for any give wall thickness, but it will also act as your wind, air, vapor and sound barrier! If all of that isn’t enough, it will also glue your dwelling together like it had on continuous hurricane strap around it! If you are after the best insulating factors and the best protection for you and your family polyurethane spray foam insulation is the only way to go!