Hot Roof in the Icy Cold: A Residential SPF Project
During a Minnesota Winter

By: Claire Trageser.

Photos Courtesy of Brendan Koop
 

When Brendan Koop began to plan his dream home, he hoped it would be a lot more than just a place to live.

“Our faith is of primary importance to us as Catholics, and so the home has been designed to include a chapel for use in family and personal prayer as part of a future addition” he said. “We also home school our children, and so the home has a dedicated school room and a library.”
Koop’s home, which is scheduled to be completed this month, will also house his growing family.

“We have lots of reasons for building our home, but they all center on wanting a home that really enhanced the way we live as a family,” he said. “We currently have two boys and two girls, ages 2 to 7, and are expecting another child this July, so the house has been designed to accommodate an expanding family with a bedroom for boys and a bedroom for girls—for however many of each we end up having—along with a nursery by the master bedroom.”

Since he plans to use his home—which he calls “Ecclesia Domestica,” or “Domestic Church”—to store such valuable commodities, it makes sense that Koop would want his roof and walls to supply the best possible protection. To accomplish this fortification, he turned to his architect brother to design the home and spray foam contractor Dan Holthaus to help create a unique combination of structural insulated panels (SIP) and spray polyurethane foam (SPF) insulation.

“With the size increase of the house over our previous house, we really didn't want to start paying lots of extra heating and cooling costs per month,” Koop said. “Also, as an engineer, I simply can’t stand inefficiency in design, and the thought of energy needlessly seeping out the home to the outdoors would drive me crazy. “

Koop’s home sits in an idyllic location on 2.6 acres (10,521.8 m2) of land in Ham Lake, Minn., which will be convenient for him and his family.

“The lot was chosen for its great scenery, and we wanted to build in Ham Lake because it is the best place for our family to be near our parish church and because it’s relatively close to my workplace,” Koop said.
However, the spot also raised a few potential issues for Holthaus and his 14-year-old spray foam insulation company, Minnesota Insealators, Inc. The spray foam application process was scheduled for Janaury 18 to 20, 2010—some of the coldest days in the already frigid Minnesota winter. On the first day of spraying, the temperature dropped to 12° F (-11 °C), which would make the air too cold to apply most spray foams.
Fortunately, Holthaus had a solution.


“We use Icynene spray foam, and one of the big reasons we use it is because it can be sprayed down in much colder temperatures than harder polyurethane foams,” he said. “You don’t have to worry about shrinkage and cracking over time.”

The house’s design called for a combination of SIPs and SPF to maximize insulation potential, but minimize Koop’s construction budget.

“We originally planned to use structural insulated panels for the entire home construction, but after our bidding process with our prospective builders, it was clear that we were going to need to cut some costs in order to make the project fit with our budget,” Koop said. “The builder we selected was very open to suggestions on how to save money, and even though they specialize in SIP homes he suggested that we could save some significant money by changing the roof construction to parallel chord trusses with spray-foam insulation.

“This would still give us nearly the same insulation value, since the SIPs were still going to need some solid structural beams in the roof that would conduct some heat out of the home, and this would also give us the vaulted ceilings were planning in the upper floor. It was also always the plan to use spray foam insulation around all of our windows and in other places where we could have thermal leaks or air leaks.”
Another aspect of the house’s design also called for a little creativity.


“They wanted a certain reveal with the house, and that reveal did not allow them to have soffits around the perimeter,” Holthaus said. “The contractor didn’t leave soffits for ventilation, so the only choice was to spray the whole assembly as a ‘Hot Roof.’”

The plan was also for the crew to spray foam on the underside of the roof’s sheathing, creating the “Hot Roof” assembly, but it hit a snag.

“We did have complications with the inspector in regard to using spray foam insulation in our roof design, due to the inspector’s unfamiliarity with the technology in this application,” Koop said.
Fortunately, the general contractor was able to work things out with the building inspector, who then gave the spraying a green flag.

With the insulation plan finalized, Holthaus’s  Minnesota Insealators was ready for action. Using a Gusmer H2035, a Graco Fusion gun, and 250 feet (76.2 m) of hose, the two-man crew sprayed 12 inches (30.5 cm) of Icynene’s open-cell foam over about 1,600 square feet (148.6 m2), producing an R-value of 40.
The crew wore fresh air intake respirators when working inside and cartridge respirators when they were outdoors, Tyvek suits, gloves, and safety goggles. An additional aspect of the job also required other safety protection.

“The stairways where we were spraying the roof assembly from inside were very high, but we had to get up close to the roof deck,” Holthaus said.  “Bottom to top it was probably 24 or 25 feet.”
To reach these heights, the crew used full harnesses and a little imagination.

“There was no place to put any scaffolding, so we had to make our own scaffolding to get up close,” Holthaus said. “It was only a 4-foot (1.2 m) area, so it wasn’t anything major, but when our guys went in and looked at it, their eyes went real wide.

“They said, ‘How are we going to do this?’ We figured it out, but we had to think about it.”
Including time for prepping the SIPs and working with the scaffolding and ladders, the job took three days. It went off without a hitch.

The house is scheduled to be finished in March, and Koop said he and his family plan to be there a long time.

“We’ll be there forever,” he said. “This was designed from the start as our final house. As great as this process has been—three and a half years in design, planning, and construction—we only want to do this once!”

Thanks to Holthaus’s crew and Icynene’s cold-weather foam, it looks like a repeat won’t be necessary.

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