Minnesota Cold

Insulated-Panel Construction Keeps Farmer, Equipment Warm on Frigid Days

Dan Miller
By  Dan Miller , Progressive Farmer Senior Editor
Insulated-panel construction keeps Steve Carlson and equipment warm on frigid days. (Progressive Farmer photo by Linnae Carlson)

Steve Carlson built his new shop for Minnesota winters. It was a cold winter this past year, even by Minnesota standards. Temperatures dropped outside to minus-20 degrees Fahrenheit, yet Carlson worked on equipment in 58-degree comfort.

Key to this shop's wintertime warmth is the energy-efficient envelope afforded his 4,900-square-foot building by a Structural Insulated Panel (SIP) wall system. Each interlocking panel (no standard lumber is used) is made of two 3/4-inch sheets of plywood that sandwich 8 inches of rigid foam plastic insulation. The panels are 4 feet wide and give the 18-foot walls a high R-value of 33. The shop ceiling has 14 inches of insulation.

The panels for Carlson's shop are manufactured by Energy Panel Structures (EPS), Graettinger, Iowa. EPS designs the building package, and the panels are numbered at the factory to speed construction. EPS says its insulated panel walls are up to 15 times more airtight than stud walls and two times as strong. The company points to research from Oak Ridge National Laboratory that shows SIP walls perform at 97% of their stated R-value. Stud-construction walls can lose up to 30% of their R-value rating. R-value is a measure of resistance to heat flow.

FLEXIBLE DESIGN

SIP walls offer design flexibility in buildings, such as a farm shop. They make possible larger clear spans and higher ceilings. These walls can accommodate electric wiring and, in some applications, plumbing -- although plumbing is not typically installed along outside walls no matter the construction technique. Wires are pulled through precut channels called chases. The chases are created during the manufacturing process.

The interior walls of Carlson's shop are finished with a factory-installed, light-gray glass board. It's a wall covering often found in dairy barns. No fasteners are exposed, making it easy to clean the walls. A pressure washer with a bit of soap does the trick, Carlson says.

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The fiberglass-reinforced plastic glass board is highly reflective of the light produced by the T8 fixtures hanging above the shop floor. The building exterior is screwed-on steel.

"I priced a pole building, and this one was a little more expensive," Carlson says. "But the energy savings made it worth [the extra expense]." The building is so tight that when Carlson opens the service door with the two roof-mounted vents running, the suction they create nearly pulls the handle out of his hand.

Carlson's shop sits just outside Welch, Minn., southeast of the Twin Cities and just off two-lane Minnesota state highway 19. The new shop was intentionally located adjacent to Carlson's large grain bin and dryer facility. It made logistical sense to have the facilities both in the same yard and with access to the state-maintained (and snow-plowed) artery, he says.

HEATED FLOOR

His quest for energy efficiency extends beyond the walls and ceiling. There are 2 inches of rigid insulation under the floor and 2 inches of insulation running 4 feet down along the foundation walls to the footings. The floor is heated by a propane-fueled Buderus boiler. It heats a water-based solution circulating through loops under the floor; each loop is 18 inches apart from the next. The boiler is more than 90% efficient, Carlson says.

With the exception of space for a workbench, office/lunchroom and utility room, the 64- by 76-foot shop was intentionally left wide open. The building is accessed by two overhead doors. One is 14 by 14 feet, large enough for a semi-truck and trailer. The other is 16 by 24 feet. The larger of the two doors has enough clearance for tractors, a combine with an 8-row head and a 16-row planter. Carlson added that he could bring a 24-row planter into the shop and unfold it.

REPAIR HUB

"The building isn't really for storage. It's more for bringing equipment in, working on it and backing it out," Carlson explained. He has cold storage elsewhere for his equipment.

The smaller overhead door opens to an interior wash rack. Hot and cold water is plumbed to an area close enough to the door that Carlson can also wash equipment outside on the concrete apron.

Wash water drains through a narrow, 1-inch slot in the floor and is collected by a surface drainage system called U-Drain, manufactured by Norstar Industries, out of Manitoba, Canada. Carlson's drain is made from 10-foot sections of U-Drain bolted together. Each section is pre-sloped to move wastewater out of the shop.

Compressed air is delivered through copper lines by way of a 5-hp, two-stage, 80-gallon compressor. The shop has an ample number of 110-volt outlets (four across the back and one by each door, in addition to those mounted over the workbench) and a pair of 220-volt outlets. Carlson ran his wiring through conduit and mounted it to the walls. Stereo sound is delivered around the shop through four Yamaha speakers.

HEAVY-DUTY CRANE

Carlson installed a jib crane with a 180-degree arc of reach. A concrete-filled, 16-inch irrigation pipe set into 5 feet of concrete supports the I-beam and a 2-ton Milwaukee hoist. The irrigation pipe does double-duty, serving as support for the storage loft directly behind the crane and running the length of the shop from front to back. Mounted near the larger overhead door, the crane is available to move supplies, equipment or mechanical components. The crane also swings over to a pair of half doors that open onto the loft.

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Dan Miller