Green Plastics? A Review of Medium Density Sprayed Urethane Foam’s Contribution to Sustainable Design 

By: Mike Richmond -Genyk Solutions

Green is in. It is trendy to use cloth bags for your groceries, to condense and divert consumable plastics and to place your plastic bags in retail stores for recycling. Everyone is doing it. Today’s consumer has bought in and marketing dollars are flowing—so LEED, environmentally sound building strategies and making ‘green’ choices are here to stay. Generally, making climate conscious decisions feels good. But defining ‘green’ choices is still very much a formless undertaking. The use of plastics for instance. Most everyone thinks that the elimination of plastics is good for the environment. But sound environmental strategies are about making logical choices. When a product contributes to durability, superior energy efficiency and provides developmental density economies of scale, a ‘green’ designer is obligated to consider the option. Even if that product happens to be a plastic.

So how can Sprayed Polyurethane Foam (SPF), a plastic, be a prudent, environmental choice? In Southern Ontario, SPF is quickly becoming the product of choice for cavity wall applications. Similarly, the growth of SPF in the Alberta and British Columbia ICI markets is dramatic. Historically, SPF in Quebec remains the insulation/air barrier material of choice. Further, Spray Foam is realizing a significant share of the high-rise residential wall insulation market. Across Canada, SPF has experienced exponential growth in residential exterior wall, floor and attic installations. Cumulatively, according to statistics gathered by the American Chemistry Council, the SPF industry has more than quadrupled product usage since 2000. But in today’s “go green” movement, is spray foam a good fit?

Admittedly, spray foam is a plastic, and as such, being considered a “green” product is challenging. However, an investigation of SPF’s performance results lends credence to the idea of SPF’s environmental contribution and the product’s considerable rise in popularity. SPF has significantly better Thermal Resistance qualities than all other commercially available insulation materials. SPF is a CCMC-approved air barrier material and has considerably better air barrier performance than the most popular membrane materials(1) . SPF is manufactured on the jobsite, and as such, is better able to conform to design/construction incongruities. Material performance distinguishes SPF as the premier insulating material.

The thermal resistance of SPF is a significant feature. When compared to fibrous insulation materials, 25mm of spray foam can yield up to 58% better thermal resistance.

Source: Insulation Materials; Installer Site Reference Manual for Energy Efficiency, Building Performance Training Institute for Construction

Further, the in-situ performance of SPF when compared to fibrous insulations multiplies the
already disproportionate product efficiencies. Consider the Oak Ridge National Laboratory
research that demonstrates that “commonly installed” fiberglass batts lose 28% of their labelled
R-value. Additionally, according to Oak Ridge research, fiberglass insulation maintained only
46% of initial thermal resistance when subjected to low outside temperatures. In comparison,
SPF maintained up to 83% of reported R-value at low outside temperatures(2). In tests performed
by Architectural Testing Inc., the Oak Ridge research was validated.

Insulation Efficiency Comparison: Fiberglass vs. Spray Foam

SPF, then, is installed at a higher per-inch thermal resistance than fibrous insulations and
performs in-situ much more efficiently.

Further, SPF weathers much better than other insulations. SPF, especially the medium density
closed cell version, provides considerable resistance to vapour diffusion. Enough, in fact, to be
considered a vapour barrier in most applications(3). Additionally, while most cavity wall insulation and membrane systems are restricted to a six-week exposure limit by manufacturers, SPF’s exposure capacity is measured in months (minimally six depending on supplier). When considering the thermal efficiency of a structure, spray foam provides the design profession with an advanced thermally resistant product, that maintains its RSI value through cold/hot exposure, and is a superior air barrier with vapour barrier capacity. Plus, the product is able to maintain integrity during exposure—a significant factor when considering construction schedules.

Because of the product’s versatility, both design professionals and constructors are realizing the
product’s cost efficiency. Given SPF’s greater thermal resistance, designers are able to get more
‘RSI’ value in less space. That is, the exterior stud members of a high-rise condominium project
can be either reduced in size or the thermal resistance can be improved. The cost savings of
reducing stud size members is often comparable to the revenue generated by the additional area
created by decreasing stud wall cavities around the perimeter of the building—hence the rise in
SPF high-rise popularity. From an energy efficiency standpoint, with SPF, 150 mm stud cavities
can achieve RSI values of up to RSI 7.0 (R40)—nearly twice the thermal resistance of mineral or
glass fibre products which provide insulation value by trapping air.
The same concept applies to cavity wall construction.

SPF as part of the rain-screen assembly is a natural fit. Spray foam’s significant resistance to vapour diffusion and air infiltration allows the design professional to specify one single material as the vapour retarder, air barrier and thermal insulation. Material and labour costs are reduced, single application productivity gains are achieved, and from a thermal resistance perspective, the designer is able to achieve considerable gains in thermal performance—all without changing the conventional dimensions of the wall assembly.

Residential housing construction is also realizing the benefits of SPF. Spray foam to the walls and
ceilings of custom homes is becoming commonplace. Again, builders are able to offer more
thermal resistance, a product that inhibits water vapour transmission, and a material that
provides superior protection from air infiltration. All in the traditional framed space. A 150mm
stud wall can now offer the energy conscious consumer with a 58% increase in thermal
resistance when compared to the historical mineral or glass fibre products. And not only is the
cost of the extraneous air barrier and vapour barrier materials recovered with the use of SPF,
protection from reverse vapour drive caused by sun-driven moisture and air-conditioned
environments is enhanced by a product able to retard moisture throughout the thermal gradient.

But it is not just material performance that distinguishes SPF. There is more to SPF than
statistical advantages. Rim joists, garage ceilings and cathedral ceilings are just some areas
where the discord between design and construction occur in residential construction. The result
of poorly fitted insulation and air/vapour barrier materials is often customer complaints and costly
warranty claims. Because SPF is manufactured on the jobsite, the product lends itself to unique
situations. Given that excessive air infiltration and exfiltration leads to significant losses in
energy, and impairs comfort, the use of SPF in critical assembly spaces is now commonplace.
SPF is an energy solution, from thermal resistance to ease of application. In short, SPF is an
energy saver, and thus, the use of SPF a responsible energy design decision.

But SPF is still a plastic, right? Cumulatively, one can make a case for the contribution spray
foam makes to an enhanced energy efficient design. As the demand for energy efficiency grows
– either by building owners who want to conserve energy or by regulatory agencies that what to
reduce CO2 emissions, spray foam’s ability to provide greater thermal resistance and superior air
barrier performance will ensure increased use of the product. But is that enough for spray foam
to be considered a green building product? Probably; afterall, all insulation materials save more
energy than the use during manufacture. However, SPF remains a plastic. Energy efficiency is
only part of the equation in appropriate environmental design. There is also the issue of material
impact. Off-gassing, VOC emissions, non-degradable waste, and design durability are equally
important. And here, one might suspect that SPF would fail.

When considering recent product developments in the SPF industry, the answer becomes
obvious. To comply with the Montreal Protocol, the spray foam industry was forced to find safer,
environmentally friendly material components. The research and product development is now
complete—at present, SPF materials are a Zero Ozone Depleting Substance (Zero ODP). Further,
the recent introduction of a new generation of blowing agent, Hydrofluoroolefin, has had a

profound impact on the spray foam market. Closed cell, medium density spray foam products
now have minimal Global Warming Potential – an industry-wide GWP of less than five.
The SPF industry has become committed to environmentally responsible products. Spray foam
raw materials are currently produced with a higher content of rapidly renewable substances –
lavender oils, vegetable oils and rainwater. SPF products have significantly reduced the use of
virgin raw materials and replaced those components with elements made from recycled plastics
(PET) and plant-based oils. The commitment to recycled content is significant. The discerning
designer can now readily locate spray foam products that make a contribution to certified ‘Green’
building strategies (especially LEED).

The insulation industry in general, and the foam insulation market in particular, received ‘the
guilt-by-association’ effect of the urea formaldehyde (UFFI) ban. UFFI’s possible ‘off-gassing’ was
determined to create a potential health risk. And even though most of today’s data would
indicate an overreaction occurred, the effects of the UFFI ban linger on for foam insulations(4)
SPF is formaldehyde-free and has never experienced ‘offgassing’. Within 24 hours of site
manufacturer, the SPF is 1/100 of the allowable limit for Volatile Organic Compounds (VOCs).
Only during the application process does one need to be concerned about VOCs, and even then,
at distances of greater than ten metres, the effects are negligible. SPF, when installed by
trained, certified and licensed installers,(5) is a safe and environmentally friendly product. In fact,
SPF can be a contributor to LEED’s ‘Low-Emitting Materials’ credit when used as a Sealant
(conforms to SCAQMD Rule #1168).

So, SPF contributes to several LEED credits – Energy & Atmosphere (energy performance),
Materials & Resources (recycled content), and Indoor Environmental Quality (low-emitting
materials). But what about the undeniable fact that SPF is a plastic product and that plastics are
not biodegradable? SPF, when discarded lays inert with other non-biodegradable products for
relative eternity—true and undeniable. However, consider that the SPF application, by definition,
is customized at the jobsite. The actual waste generated is considerably less than factory
manufactured insulation products that are cut to fit at the jobsite. Here is where most
environmentalists agree that choosing the benefits of an energy efficient product that solves a
multitude of efficiency design situations, outweighs the minimal downside of the product.
And the product’s endless longevity is consistent with another cornerstone of environmental
design – durability. For the same reasons that SPF does not deteriorate in the landfill, the
product remains constant in the wall assembly, outlasting even the most ambitious design
projections. SPF’s moisture management is the key. First, the product resists moisture
migration. Second, any moisture that does penetrate the insulation dries within typical
temperature cycles exclusive of any deterioration of SPF’s thermal resistance(6).

In short, SPF can provide the water resistive barrier, the air barrier, the thermal barrier and the
vapour barrier functions all in one easy and single application to the building envelope,
eliminating the need for a multi-layer application

Can a plastic considered a green building product? If the product contributes to elevated energy
conservation, is a zero ozone depleting substance, has a minimal GWP, and is manufactured with
a high recycled content, it is worth considering the benefits. Further, more efficiency in less
space contributes to developmental density. SPF’s superior resistance to vapour diffusion
contributes to combating the effects of making a building tight; and, the multi-faceted properties
of SPF (insulation/air barrier/vapour retarder) produce obvious economies of scale and allow the
design professional the opportunity to participate in elevated energy efficiency design. Today the
public is ‘consumered’ with the idea of ‘going green’— SPF is a real option in making momentum
reality.

Mike Richmond, [email protected]
Mike Richmond is employed by Genyk Polyurethanes as a Building Science Specialist. He is a LEED
Accredited Professional and a Building Science Specialist of Ontario as sanctioned by the Ontario Building Envelope Council.

(1). The most popular air barrier membrane has achieved a rating of 0.005 L/s.m2 air leakage when tested using ASTM E283. Under the same conditions, SPF achieved an average 0.00014 L/s.m2 rating.

(2). SPF Outperforms Fiberglas in Attic Insulation Performance Tests at Oak Ridge National Laboratories,
July 2005.

(3). G.Finch, & Dr. J. Straube, “Field Performance of Spray Polyurethane Foam: The Role of Vapour
Diffusion Control”, April 2007.

(4).Subsequent studies and failed court cases have established the overreaction to UFFI.

(5). Spray foam installers are obligated to conform to the conditions of a stringent Quality Assurance Program.
Obligations include Installer training, inspection and certification as well as random and mandatory 3rd
party inspections.

(6). G.Finch, & Dr. J. Straube, “Field Performance of Spray Polyurethane Foam: The Role of Vapour
Diffusion Control”, April 2007.