RetroFoam, Closed Cell and Open Cell Spray Foam

Summary of foam attributes and misnomers…

A. RetroFoam R4.6 per inch thick or R16 in a 3.5″ wall cavity, R18.4 in an older home with 4″ stud INJECTION PRESSURIZED CAVITY
B. Open Cell foam 3.7 per inch thick or R13 in a 3.5″ wall cavity after it is shaved SPRAY APPLICATION OPEN CAVITY
C. Closed Cell foam 6.6 per inch thick or R13.2 when sprayed at 2″ thickness normally SPRAY APPLICATION OPEN CAVITY

Sound Attenuation:
A. RetroFoam has the highest at STC 40 to 50 and adding 3” sound attenuation blankets above drop ceilings helps
B. Open Cell is still good with an STC39 rating for ASTM-E90
C. Closed Cell is not good for sound attenuation and can actually be detrimental to such

Air, vapor and water sealing characteristics:
A. RetroFoam can shrink up to 3% and allow minimal air flow through walls, will not absorb moisture itself nor is it a moisture barrier
B. Open Cell .5lb foam is considered an air barrier, but is neither a water or vapor barrier
C. Closed Cell 2lb foam is an air, moisture and vapor barrier, is normally used in residential as moisture resistant but not for water proofing. Heavier density does not mean better waterproofing. Specialized spray foam for waterproofing is in a separate class. Coatings over foam creates waterproofing.

Misnomers of each foam can be a fairly open ended conversation depending on application.
A. RetroFoam normally should only be used in a pressurized wall cavity installation, some exceptions can apply
B. Closed Cell directly on a shingled roof eliminates all ventilation to roof deck
C. Open Cell directly on a roof deck reduces air ventilation and is commonly installed on ceilings OR roof decking depending on roof pitch and space use
D. Most all building inspectors, from our experience, cannot agree on comparisons of foam to fiberglass R-value benefits or requirements.

Job site conditions required for each foam
A. RetroFoam requires relatively low humidity home environment during and immediately after install for proper curing
B. Spray foam has significant off gassing / harmful ordo until it cures, occupants should stay away for a day
C. Spray foam is nasty and can go everywhere if not contained, therefore prepping job site is important
D. Prep, plastic and site management, working space, are critical to a successful and profitable foam job

From our calls from commercial clients, facing sound issues in recent construction, few architects are up to date on sound attenuation. Most architects are still specifying sound attenuation blankets in commercial office spaces, who then turn around and call us to RetroFoam. Stucco / Efis is replacing foam in block in some specs.