Spray Polyurethane Foam (SPF) is a manufactured-on-site form of building insulation that has gained some acceptance in recent years. SPF is typically composed of two chemical components that, when combined in prescribed ratios by a properly trained and protected installer, can be an effective insulator. SPF is also available in two varieties — open cell and closed cell — each with specific installation requirements and/or performance attributes that make them more or less suitable for home applications. Due to its lower price point, open cell Spray Polyurethane Foam is used much more frequently than closed cell, although installed prices for both variants are substantially higher than that of fiberglass insulation - making the return on investment much more difficult to obtain.
FIBER GLASS v. SPRAY FOAM: THERMAL PERFORMANCE
Fiberglass insulation – in both blanket and blown-in, or loose fill form, is manufactured in plants under controlled conditions, following established quality protocols and continuously tested to verify thermal performance.
Foam insulation – as the product of two components which must be mixed at the point of installation, it is essentially manufactured” at the job site. Thus its’ in-place performance is affected by ambient conditions (humidity and temperature), equipment operating efficiency and installer knowledge and experience. Any or all of the above factors, individually or in combination, can lead to inconsistencies in product density or incomplete filling of cavity spaces.
FIBER GLASS v. SPRAY FOAM: AIR INFILTRATION
A comprehensive field study of four insulation types (fiber glass batts, blown-in fiber glass, spray foam and wet-spray cellulose), conducted on standard, production homes, concluded there was little difference with regard to air leakage. The study states, “The individual air-sealing practices of the builders and their insulators often had a greater impact on air leakage than did the insulation products themselves”.
FIBER GLASS v. SPRAY FOAM: MOISTURE CONTROL
Most spray foams meet only the minimum qualifications as a vapor retarder. In addition open cell foams will absorb water both in liquid and vapor form. Therefore it is necessary to provide an approved vapor retarder, when required by code.
FIBER GLASS v. SPRAY FOAM: HEALTH & SAFETY
While appropriate Personal Protective Equipment should always be worn by installers of any insulation type, the requirements for spray foams are much stronger (fully enclosed suit with oxygen supplied), and the risks of exposure much more severe, including compromising the immune system. The health risks associated with Spray Polyurethane Foam chemical exposure require that other trades vacate the job site during installation and for up to 24 hours after.Drywall installers often must spend additional time removing overspray from framing prior to drywall installation.
Spray foams are highly flammable at the time of application.
Before You Pay More for Spray Foam Insulation, Consider These 5 Facts:
1. Spray Polyurethane Foam (SPF) is manufactured on site and its performance is highly dependent on properly trained installers.
2. SPF creates the potential for moisture buildup, a common cause of wood-based building failures.
3. SPF cannot provide a complete air-sealing solution and does not seal the top or bottom plate.
4. SPF lengthens the build cycle due to increased health risks for other trades during installation.
5. SPF costs more to install with no performance increase over other air-sealing and insulation systems.