Spray Foam Insulation Melting wires?

[DavidL]

I wouldn't say it defeats the purpose.

Sprayfoam has higher R per inch. Sprayfoam provides an intrusion barrier and adds structural rigidity that cellulose and fiberglass do not (as much).

If the goal was R19, then he is not defeating the purpose, but accomplishing it.

What might be suspect is paying for 2x6 walls if that sized wall is not being required for weight bearing or other dimensional purpose other than a larger insulation cavity.

I blended foam block walls, 2x6 cellulose, 2x4 foam filled and 2x12 cellulose rafters to accomplish the multiple goals for my home. I have walls of windows that the foam was excellent for (fixed windows) as it really tightned up the bank.

What was my mistake, was using low density foam for the non fixed windows as many are now in need of clearancing.

It is a PITA to run wires post install thru foam. I provisioned for this using different wire channel strategies dependent on where in the home (including wire chases in the ceilings).

Our new house just got foamed today. The secret is to use closed cell foam and only 2-3 inches thick on a 2x6 wall. I have 3-4 inches
of dead air space between wallboard and insulation to run future wiring or whatever. My walls are about R19 or so with 2.5 ish inches.

That's more than enough. 80% of heat loss is through ceiling and about 15% through walls.

That defeats the purpose of spay foam.

You can use Carlon products for flexible raceways and low voltage rings.

Carlon products

 

[86turbodsl]

Our new house just got foamed today. The secret is to use closed cell foam and only 2-3 inches thick on a 2x6 wall. I have 3-4 inches
of dead air space between wallboard and insulation to run future wiring or whatever. My walls are about R19 or so with 2.5 ish inches.

That's more than enough. 80% of heat loss is through ceiling and about 15% through walls.

That defeats the purpose of spay foam.

You can use Carlon products for flexible raceways and low voltage rings.

Carlon products

No the purpose of foam is to seal the wall from infiltration and provide a high r-value per inch.
I suppose conduit would be a good way to go, but I never found a good system that didn't cost
a fortune to accomplish that. I used Arlington LV boxes.

Back to the insulation. Infiltration is a Very big source of heat loss. Stop that, and you've already accomplished most of
what the purpose of insulation is. Cellulose on top of the foam WOULD have increased the insulative value of the walls,
but as I stated earlier, wall insulation has a very small impact on overall energy efficiency.

I preferred to spend my my extra money on geothermal and radiant heat over incremental R value.

 

[sic0048]

Most houses have 2x4 construction, so it would make sense that 2x6 construction would allow a gap between the wall board (the inside drywall) and the foam. The gap he mentioned is the same difference between using 2x4 and 2x6 construction.

I'm not sure how an installer could spray foam and leave a uniform 1-2" gap, but that is a different story.