SPF: Polyurethane Insulation and Foam Roofing

SPF Shields Michigan Home

Sprayed polyurethane foam is unique in that it is manufactured on-site. There are countless compositions for this plastic based product all based on the various intended applications. The type of compositions used for foam roofing or for SPF foam insulation are both very similar in density, composition, and in R-value performance. An R-Value is a benchmark for measuring the effectiveness of any insulator, with a baseline where 1 inch of wood has an R-value of about one. As an example, an R-Value of 1″ of low density foam might be 8, which represents 8″ of wood.

polyurethane foam insulation
An applicator sprays polyurethane foam to create a monolithic barrier that conforms to the shape of the home, effectively insulating and trapping vapors.

Polyurethane Foam Based on Two Components

Generally, to create sprayed polyurethane foam there are two components, the base plastics and an activator that helps form the millions of closed cells and allows the foam to self-flash to a substrate. Sprayed polyurethane foam amazingly versatile and can conform to any shape which makes it ideal as an insulator, especially in residential or commercial construction applications.

The two components are kept in a heated hose to ensure the elements stay at proper temperatures for optimal results. Sprayed polyurethane foam is also ideal as an external insulator, where there may not be existing internal space to add insulation to a structure. Eichler homes or cargo bin style homes are two examples of structures which have no internal space for insulation, so insulation products must be added to the exterior (e.g. foam roofing).

Polyurethane Foam is High Tech

Sprayed polyurethane foam was originally discovered as an ideal insulator, designed to protect space shuttle fuel tanks. Further adaptation allowed polyurethane foam to be used in production of plastic vehicle moldings, and for refrigeration applications, especially for walk-in freezers and refrigerators. In extremely harsh climates, such as those found in North Michigan, polyurethane foam is used as an insulator, to shield homes from the harsh external climates.

SPF Foam Conforms to Any Surface

Since SPF foam can mold to any surface, it works great in applications where traditional fiberglass or cellulose insulation fail due to space and size constraints. And SPF has even more unique qualities; SPF foam has extremely high R-values (often 3-4 times more than fiberglass or cellulose) and closed cell foam blocks air infiltration. Aside from all that, traditional materials such as cellulose or fiberglass have major performance degradation in extreme heat or cold.

SPF Foam Performs Beyond Just R-Value

In other words, in laboratory tests, traditional insulation performs as low as 20% of their stated R-values, while polyurethane foam usually performs at 70% or more of the stated R-values. In other words, in extreme cold or hot conditions, polyurethane foam is a even more superior to traditional insulation products. This is why SPF has risen in popularity in many applications, including foam roofing an insulation.

Sprayed Polyurethane Foam (SPF) Insulation

Case Study: 7,000 Square Foot North Michigan Home

Although Tony Harfert, founder of Harfert Builders won the contract to SPF insulate a 7,000 square foot residence in Northwest Michigan, he felt no relief. This was due to the fact that his team would be required to install the insulation in the dead of winter, in biting cold conditions. The homes position between lake superior and lake Huron meant exposure to sometimes 50 mph plus winds, putting the thermometer to negative 37 degrees Fahrenheit (and often well below negative 50 degress Fahrenheit with wind chill factor included).

Harfert Builders Background

45 year old Tony Harfert had 12 years experience as a general contractor, and three years of SPF experience (for a total of 15 years experience) before starting the North Michigan custom home project. Three years before building the Michigan custom home, Harfert Builders saw that sprayed polyurethane foam (SPF) was quickly becoming a standard in the frigid climes of the Northern United States.

polyurethane foam insulation
Excess polyurethane foam is shaved down, creating a seamless insulation barrier that perfectly conforms to the shape of joists, rafters, and other application surfaces.

Harfert Builders Used Demilec Foam

This led to the decision for Harfert to become a certified distributor for Demilec. This included 4-days of school in Texas, as well as a quality assurance program called Inseal-Right. This program allows Demilec to randomly inspect applicants projects during the first 6 months. Demilec credits this quality control program as primary reason for 11 years of no call backs or warranty issues for their SPF products (used in foam roofing, insulation, and other applications).

Extreme Weather Makes Deadlines Difficult

In order to complete the prominent physician’s home on-budget and on-time, Harfert and his SPF crew would face the challenge of insulating and protecting the home before extreme weather conditions could do any damage (such as causing the poured concrete basement walls and floors to buckle before curing). The main floors of the home would be wood, so only the basement floor had this potential issue.

Propane Heaters Prevent Buckling

A few propane powered construction heaters (300,000 BTU “Mr. Heater”) kept things warm in the basement to ensure proper cement curing, while an ES laser thermometer was used to assure temperatures remained in a safe control range. One inch of 2lb closed cell polyurehtane foam (Demilec LLC “Heatlok”) was applied to the basement walls (closed cell foam is also used in foam roofing).

This would allow the heaters to more effectively keep the in-progress basement walls and floors from buckling. Otherwise, the 30F below zero outside temperatures would wreak havok on the incomplete home. For the next step, the construction team framed the basement with 2x4s. After the electricians finished their work, the walls between the studs were sprayed with demilec selection 500 (1/2lb open-cell foam; this is very different from the closed cell foam used in foam roofing).

Caulk Insulates Seams to Prevent Air Infiltration

As the construction workers finished each section, Harfert Builders contuned to insulate each section, including the roof system which included over 58 valleys, hips, and ridges. Sherwin-Williams’950 acrylic caulk was applied directly into any seams to prevent direct air migration. Overall, the design of the home would have prevented it from being properly insulated against air infiltration with cellulose or fiberglass. Before the project was even complete, 50mph and 60mph winds could not be heard from inside the home–due to the complete prevention of air infiltration.

A Job Well Done

While inside the home, the effects frigid winds outside whipping across the great lakes could be seen–in stark contrast to the quiet peaceful environment inside the home. The Sprayed Polyurethane Foam (SPF) insulation truly sealed the home from the elements, creating a temperate pleasant indoor environment.

5 thoughts on “SPF Shields Michigan Home”

  1. Polyurethane foam is really a great invention. Now that I am more informed about SPF foam I think I would use it on my home for insulation, especially if I ever moved to a cold northern area. I am guessing the doctor saved a lot of money by getting polyurethane spray foam insulation during construction. Filling the walls afterwards would probably require a lot of tearing down and rebuilding type work. I’ve heard icynene foam (icynene sounds like a spin-off of theoretical ice-9 solid water sci fi name maybe?) can be poured. I’ve heard some contractors just poke a hole in hard to reach places and fill the walls with icynene foam. I think I’ve heard icynene foam is based on castor oil. This is truly even more strange than soy-based foam. I suppose being even greener doesnt hurt as long as these types of foam don’t cost a lot of extra money.

  2. Why can’t I find anything about whether you can use this material for roofing where there are heavy snow loads. I am interested in lightening the roof load.

  3. I am looking for how to reduce load on a Colorado roof I can’t find anything about snow loads with this material

  4. Regarding snow load, the closed cell spray polyurethane foam we use in roofing applications is rated to support 40 psi. In other words, the foam roof system will support a snow load of up to 5760 psf! Even Antarctic conditions do not have snow loads anywhere close to this high. For example, 100 psf is a very high snow load. In any case, beams and deck boards will fail under an unusually heavy snow load long before the roof material. Thus, you have no need to worry about snow loads as far as foam roofing materials are concerned.

    I’m aware of RIM “Roof Ice Melt” systems which are installed at the perimeter of sloped roofs. A manufacturer of this product may be able to recommend a system for melting snow over more expansive roof areas where you want to reduce snow load.

  5. I am also interested in insulating a roof in a cold climate, but the limited research I have done so far says you can’t use SPF at 50 psf or higher snow loads – that you need a vented roof. The justification I saw was that the insulation of the deeper snow on the roof with these higher snow loads is more prone to cause ice damming.

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