Yes, there is a larger investment, but we have found that most of our customers are paid back the difference over a 3 to 5 year period through energy savings.
Yes. Spray foam has more density than fiberglass and its physical properties attenuate sound more effectively. Note: It is very difficult to specify how much sound will be reduced unless a specific sound wall assembly is designed (i.e. staggered stud, etc.).
You would spray foam at the same time as traditional fiberglass insulation, after passing mechanical and framing inspections and before hanging sheetrock.
No. Spray foam insulation is applied to the underside of the roof deck, raising the insulation plane from the ceiling to the roof deck. This creates a conditioned space in the attic area with typical temperatures in the 80° - 90° range instead of the normal 150°.
Both open-cell and closed-cell foam are great insulators. Both provide an excellent thermal barrier and air barrier. How they differ is that closed-cell foam is waterproof and will not let water move through it. Open-cell foam will allow water to move through it and dry. Insulation should not stop water. Roof, wall, and crawlspace assemblies are designed to keep water out. If water somehow does get into those assemblies, it needs to be able to dry out, especially in wood structures.
Spray foam insulation's air sealing properties are the primary reason for its superiority over fiberglass. Fiberglass, no matter how well it is installed, does not provide an air barrier and allows air to move through it. This allows the two climates (inside, conditioned air and outside, unconditioned air) to combine and create potential condensation inside walls and building assemblies;