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Home | Spray Foam Roofing | Domes in the Wilderness
Polyseal uses SWD Urethane spray foam in a dome building roofing project in Alaska.

Domes in the Wilderness

Spray foam and polyurea combine to protect two domed buildings near an Alaskan radar site

By Juan Sagarbarria

Radar bases. We know they are out there, yet we cannot pinpoint many or often any of their locations without referring to a detailed map or executing a strategic search engine query. Rightfully so, being that their ultimate purpose is to safeguard the long-range radar that monitor American skies, so they are generally not open to the public. Ergo, the bases’ location can be remote, especially if they are in the state of Alaska – but just how remote are we talking about?

Oh, just a mere 40 miles south of the Arctic circle, along the Brooke Mountain Range, which stretches 700 miles from west to east across Northern Alaska into Canada’s Yukon Territory in an area that is caressed by howling winds and the intermittently changing temperatures of the Arctic region; a location where sightings of all types of specimens from flora and fauna, including grizzly bears, are commonplace; an area that can only be accessed by a small engine plane – that is where you can find the Indian Mountain Long Range Radar Station (LRRS).

The LRRS is currently under the command of the Pacific Air Force’s 611th Air and Space Operations Center and it is part of 15 radar sites comprising the Alaska Radar System (ARS) maintained by ARCTEC Alaska, a subsidiary company of the Arctic Slope Regional Corporation that provides on-site experienced facility specialists that operate each site year-round. Near the LRRS, two domed buildings were constructed in the mid-’80s: One serves as the ARCTEC workers’ living quarters and the other houses a mechanical/power station. For safety reasons, the station, including the domes, had been built far below the actual radar dish, which was nestled in a higher location in the mountains.

Dome Trouble

When the two domes were built 30 years ago, they were designed as half-spheres of aluminum I-beams with aluminum-skinned structural insulating panels (SIP), both domes having a 100-inch diameter. Even though the aluminum structures seemed ideal due to their excellent corrosion resistance – and even after they proved to be aesthetically pleasing upon construction – there was one major issue that the builders did not take into account: The extreme Alaskan climate predominately driven by rain and snow. Due to these extreme conditions and temperatures, the domes’ metal substrate expanded and contracted, causing the adjoining seams to break, allowing water infiltration. Between the constant rains and snow melt, the domes endured costly damages.

Over the years, several methods were used in hopes of repairing the problem. Different patching materials were utilized and although they temporarily reduced the damage inflicted by the leaks, they never solved the leaking problem in its entirety. Later on, the building owners turned to insulation as the solution, a type that could bolster these structures and help them withstand the extreme temperature changes inherently occurring at the LRRS. That is when ARCTEC, in conjunction with the Air Force, contracted Polyseal Insulation LLC to install a spray-applied roofing system that could end their troubles for good. Polyseal came up with a roofing system that included spray polyurethane foam with polyurea coating to cover the entire area of the two domes, amassing 44,000 square feet.

“Ever since they were installed, the buildings have leaked like a sieve whenever it rained or snowed,” says Polyseal’s Paul Broderson. “Over time, the SIP panels had more than likely become wet and inefficient, so this roofing system is exactly what these domes needed. Not only do spray foam and polyurea stop the leaking, their combination will make a huge difference in terms of energy consumption.”

An Apt Work Area; An Ideal Surface

The six-man Polyseal crew, the materials, and equipment were all flown in to the LRRS remote location. Upon arriving on site, ARCTEC designated an 8′ x 20′ shack equipped with a 300 amp electrical panel as the Polyseal crew’s working area. The crew applied two inches of foam to the exterior walls and underside of the roof of the shack to maintain an ideal temperature inside the work area. Furthermore, they mounted an overhead heater and subsequently turned on their three machines on.

They used proportioners manufactured by Polyurethane Machinery Corporation (PMC): Two PH2 Series Hydraulic Horizontal Pump proportioners for the foam application, and one Classic PH-40 Series proportioner for the polyurea application. Then, after a thorough examination of the buildings, the crew noticed that the roofs had many variations of existing coatings on them, so adhesion on the lower part of each dome building became a cause for concern. In order to prevent the foam from becoming delaminated around these areas, the Polyseal crew mechanically fastened a woven monofilament, erosion-control mesh around the base of the domes. The mesh provided a cost-effective solution that yielded an ideal surface onto which the foam could adhere to without removing the existing coating materials, not to mention it prevented the foam from future cracking.

“The installation of the mesh was extremely important because the numerous patch jobs and previous fixes had generated a questionable surface for the foam to adhere to,” notes Broderson. “In addition, the cost to remove the existing patchwork coatings would have increased the cost of the job exponentially. Once applied, the foam would saturate the mesh and form an extremely strong bond. This also contributed to the roofing system’s durability, making it virtually indestructible even in the face of forces that could collapse the rest of the building. Basically, we wanted the building to be able to collapse underneath the foam and have the foam still stay there.”

Preparation is Key

Broderson reveals that a general safety plan was implemented specifically for this project, one that contained four categories: Fall Arrest, Personal Safety, Respiratory Safety, and Hazard Analysis.

Height was a considerable factor throughout this project. The Polyseal crew constructed 16-foot scaffolding to facilitate the application of the materials onto each dome at varying heights. The crew made sure to be protected while working on the scaffoldings, so they outfitted themselves with a 10 mm rope system for fall protection. When doing vertical work on the top of the domes, the sprayers used a two-rope system. Even though OSHA fall protection requirements stipulate that only a one-rope system is required, Polyseal was adamant about being as safe as possible in case one rope failed. The crewmembers were equipped with a Petzl B71ALU ASAP Lock Mobile Fall Arrester hooked to a safety harness while they worked.

“We utilized a tension rope for holding, ascending, and descending,” said Broderson. “The second rope was used for fall arrest only, and we were hooked on to our ASAP devices for extra protection.”

For the majority of the application, the crew used fresh air respirators to guard themselves from chemical inhalation. Notwithstanding, some forest fires in the area generated smoke that found its way into their fresh air machines, contaminating the air supply. To handle this problem, the Polyseal crew simply switched to Allegro full-face mask respirators whenever smoke became a problem. They also wore G.I. Polypropylene suits, Tyvek suits, gloves, and steel-toed boots during the material application.

Given the remote location of the site, overspray damage wasn’t an issue. However, the Polyseal crew didn’t throw caution to the Alaskan wind. They monitored the site to ensure that all vehicles were moved as far away as possible and continually communicated with ARCTEC by two-way radio so they’d be made aware in case they needed to stop spraying for any given reason.

Retrofit: Engaged

During this project, Polyseal collaborated hand-in- hand with spray foam and coatings manufacturer SWD Urethane, who supplied the materials constituting the roofing system. In three lifts, they applied four inches of Quik-Shield 125, a 2.5 lb. closed-cell spray foam formulated by SWD Urethane. In total, 52.5 sets of foam were installed throughout the project. The applicators monitored and adjusted spray patterns to ensure that the foam was applied smoothly and uniformly. First, the crew installed a two-inch layer, followed by two one-inch layers. Moreover, after the second lift, the Polyseal crew allowed the foam to cure for 15 minutes before applying the third 1.5-inch lift. Then, a light, half-inch pass was applied.

Broderson explains the strategy behind this method, “Creating a smooth surface with the spray foam is extremely important in roofing jobs because it allows for even distribution of the coating. That’s why, after the third lift, a very light pass of half an inch was done in order to have a nice surface for the polyurea UV coating to stick to.”

And, quite successfully, the polyurea stuck. The Polyseal crew topped off the foam with two coats totaling 80 mils of SWD Urethane’s tan-colored Quik-Shield 952, a UV-resistant, elastomeric polyurea coating. The first coat was applied at 40 mils in one direction and the second 40-mil coat was applied at a 90-degree angle from the first. According to Broderson, this was done to ensure proper coverage in case there were any uneven spots on the foam surface. Now in place, the spray foam roofing system effectively seals the roof from water infiltration, provides wind-uplift resistance, insulates the building, and eliminates expansions and contractions that caused the roof to leak in the first place.

Benefits Delivered in a Timely Fashion

According to Broderson, the benefits are evident. “The biggest benefit of the new spray foam roofing system is that the roof no longer leaks,” he notes. “Spray foam has exceptionally high dimensional stability and insulating properties, which is important in an area where the temperature can plunge down to -68 degrees F. Due to the dimensional stability of the spray foam system, there will be an efficient monolithic seal over the two roofs. This resolves the issues of flexing, cracking, and leaking, and there is no longer a need for constant patch jobs or any kind of repairs. The increased durability from the spray foam solution is much more sustainable for maintaining the buildings over a long period of time.”

Foresight – on Polyseal’s part – was the name of the game during this project. That’s how they were able to finish the application in a timely manner. This was accomplished, in part, via the never-ending Alaskan day; that is to say, the Polyseal crew got through their day without witnessing a setting sun in 24 hours. Due to the additional daylight hours, the Polyseal crew managed to move through the project faster.

“We could work continuously without limitation, until we felt we got to a comfortable stopping point,” says Broderson. “We would be surprised when we would discover it was 10 p.m. and we were still spraying.”

Broderson also noted that the spray application is going to allow the buildings to heat more effectively and reduce energy bills. Considering the proximity to the Arctic, that is more than a benefit – it is a blessing for the LRRS operators and ARCTEC residents alike.

“The facility is heated by waste heat from the generators that power the radar,” points out Broderson. “Thanks to the spray foam, LRRS doesn’t have to generate extra heat beyond what the generators produce. This saves fuel, which is vital in such a remote area, since everything the ARCTEC crew needs must be flown in.”

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