Spray-on expanding foam wall insulation....

rswyan · Jan 29, 2006

( 1*How can you have a 7'' depth? )
Very easily - 2 x 6 3-ply posts on their long side are 5.5" - add to that the additional 1.5" from the 2 x 6 girts that are nailed to the outside of the poles that the sheetmetal is hung on and you have a depth of 7".

( What size are your post?? )
3-ply 2 x 6

( 2*You don't want to fill the 7 '' with foam. )
I don't ? /forums/images/graemlins/grin.gif

Why's that exactly ?

Actually I'm planning on using NuWool which is not foam - it's sprayed-on cellulose ... so you are correct - I don't want to fill it with foam.

( Icynene automatically gives you an air space for wiring don't be so foolish as to fill it up with the foam. )
My wiring will all be in before the NuWool cellulose is sprayed in so that shouldn't be a problem. And for that matter I don't think that sprayed-on cellulose poses quite the problem that foam does.

( 3.5 inches is all you need to fill. )
Here's my take on that:

The difference in cost between filling the cavity to 3.5" versus 7" is probably minimal when compared to the cost of just having the crew out there doing it. IOW, I don't think that it's going to cost me all that much more to fill the cavity to it's full depth, rather than just to 3.5".

Secondly, failure to fill the cavity to it's full depth does two things:

A. It gives moist air a place to go within the wall cavity (whereas if it was filled to it's full depth there would be no place for the air to infiltrate to.)

B. Leaving it not completely filled creates the potential for convection loops within the wall cavity.

bebster · Jan 30, 2006

Good points on simplifying it for a single step. My problem is that Icynene is a franchised product and there seems to be just one dealer in my area that carries it and installs it. He doesn't want to give me a quote until I'm farther along. So I guess I really don't have a full handle on the cost. I wonder if anyone who has used it can give me some comparable costs for Icynene installation?

Bruin4 · Feb 11, 2006

USE IT !

The new spray foams are amazing. Although more expensive than fiberglass, they actually work to air seal your home. I just did a "blower door" test on homes in the north east, the results were astounding - the homes that were air sealed with the spray foam performed 100 times better than ones insulated with fiberglass.

I am a contractor and will never install another piece of fiberglass again!

A great resource for DIY spray foam ( less $ than the Tiger website as well) is Loyola Enterprises http://store.yahoo.com/loyola-1/

I have not purchased from them yet but am placing an order today.

Also there is some talk in the industry that fiberglass batt insulation will soon be out lawed, the Tiger foam appears to be environmentally friendly - there are also other similar products are actually made out of soybeans - Great for us if they are locally grown!

good luck

Bruin

guyrj33 · Feb 14, 2006

I took a look at the Loyloa site. They show a 600 board foot package for &630: that's $1.05 per bf.
A 2x4 cavity on 16" centers is 4 bf per linear foot. I used 3.5*12*14 to estimate.
With the foam running 1.05 bf a linear foot of wall cavity would be $4.20 to insulate. $4.20 per foot!

scesnick · Feb 14, 2006

I have used the spray foam in the small cans for various cracks around my windows and whatever. It seems to break down frter a year or two and if you just touch it it will turn to a dust. I wonder what the life of this stuff would be ona full blown insulation job? I don't think i would want to re insulate after a few years, especially at that price!

goaliedad · Feb 14, 2006

not sure about this, but I think the can stuff breaks down when exposed to UV- inside the wall cavity should not be an issue.

midlf · Feb 15, 2006

If you paint the foam it does not break down. As stated it's a UV/sunlight thing.

Alan L. · Apr 26, 2006

I am in the process of planning a new house and have researched the foam insulation products in depth.

I plan to use an open cell foam called Sealection 500, which is similar to Icynene. It produces an R factor of only 3.8 per inch, not much better than fiberglass; however everything I read says forget about R factor because it eliminates the movement of air which is the number one cause for heat loss.

Here in Texas they recommend R38 in a cathedral ceiling, but the manufacturer of Sealection 500 says 5.5 inches (about R20) will outperform R38 fiberglass by a wide margin.
The also have a closed cell product that rates about R7 per inch, but don't recommend it be used in roofs because it does not allow moisture through, thus a leak could go undetected thus rotting out the rafters and decking material.

I have a rough quote of $1.30 per square foot of wall space to fill a 2 x 4 wall (installed professionally). The same amount of fiberglass is about $.40 a foot, so its about 3 times as expensive. He said 5.5 inches in a 2 by 6 rafter would be about $1.60 per foot, but he would have to see the job before giving a quote.

I plan to do a "hot roof" installation, which means all of my insulation will be sprayed up against the roof decking, with no insulation in the ceiling. There will be no attic ventilation, in fact the attic will be a conditioned space, supposedly within 7 degrees of the living space. Ice dams are not a problem here in Texas, and I will be installing a metal roof, which is not damaged by the heat of a nonventilated attic.

The manufacturer rep said that the installers don't just spray the foam, they also caulk every joint between framing material, that is where two pieces come together such as double studs, top plate etc. All of those seams are caulked before they spray in the product to be sure and get a perfect seal.

He also recommended using a radiant heat barrier on the outside of the OSB of the wall, with an air space between that and the brick or rock facing. He say Tyvek has a new radiant barrier that should be considered instead. He said there was no need to use a radiant barrier on the roof since there is no air space.

The manufacturer in Arlington, TX says the product is absolutely safe, water based, no formaldihyde, and nontoxic in a fire.

SCDolphin · Apr 26, 2006

My brother lives in Montana. He built a 28-3000 sq ft house and foamed ceiling walls etc. There house is on a bluff with very high winds in the winter. They rareley ever turn on the gas heat; they only run a little wood stove.

The foam seals the place, makes it ultra quiet and adds increase structural rigidity. If anyone would like t email him let me know. He built his house about 8 years ago