Builders using SIPs

A study conducted by the RS Means unit of Reed Construction Data shows that residential builders can reduce their framing labor needs by as much as 55 percent by using structural insulated panels (SIPs) instead of conventional “stick-building” methods.

The study was conducted on a two-story, three bedroom, Cape style home in Tilton, New Hampshire. Engineers from RS Means observed the construction of the home and compared the workers’ productivity with a benchmark home built using 2×6 construction and fiberglass batt insulation.

SIP Panels cut labor and installation time The SIP installation crew spent 130 fewer hours framing the exterior walls and roof of the home by eliminating many time-consuming steps from the construction process.

Used for walls, roofs, floors, and foundations, a structural insulated panel sandwiches a rigid foam insulating core between two structural skins usually made of wood. The seamless, closed-cell rigid foam core reduces air leakage and thermal bridging through the panels by providing a continuous span of insulation. In a large, single component, SIPs perform structural, insulating, and air sealing functions, and install quickly saving builders time and money.

The Tilton home used energy-efficient SIPs for all exterior walls, the roof, and two window dormers. Complex and hard to insulate dormers are easily pre-assembled using SIPs and hoisted into place with a crane. Installation of the SIPs dormers was found to be 25 percent faster than the benchmark home.

By using precut channels, or “chases” in the foam core of the panels, electricians were able to wire the Tilton home with 11 percent fewer hours than its 2×6-framed counterpart, according to the study.

Building with SIPs also reduces waste since they arrive at the jobsite prefabricated and require less measuring, cutting and framing. The study noted a 93 percent material utilization rate that sharply reduces the cost of jobsite debris disposal.

SIPs create a well-insulated and airtight building envelope, and SIP-built homes repeatedly demonstrate annual energy savings of 50-60 percent when combined with other energy saving techniques. For example, SIP test homes monitored by the Department of Energy’s Oak Ridge National Laboratory (ORNL) show heating and cooling costs as low as 32 cents per day. Airtight construction also provides better indoor air quality for occupants.

Due to the airtight qualities of SIP construction, the EPA waived its blower door test requirements for any SIP homes qualifying for the Energy Star program, thereby reducing the cost of an Energy Star home inspection. Coupled with federal and state tax incentives available for energy-efficient home construction, SIPs offer builders another money saving option.

Labor Case Studies

Study 1 Project:

Labor time estimate for setting R-Control SIP wall panels used to build the structural and insulated envelope of a 3978 square foot duplex.

R-Control SIPs:

Panels were supplied from factory: Cut to length and width. Spline and plate pockets were factory cut.

Scope of work – Walls:

  • 312 lineal feet of 8 ft. high walls – installing 2X plate material in factory cut openings and header openings, top plate.
  • Bottom sill plate over conventional floor system, as in SIP-105.
  • R-Control SIP was set over sill plate, as in SIP-105.
  • Panel to panel connection was done using surface spline, as in SIP-102 and SIP-102d.
  • Corner connection was done, as in SIP-103.
  • Door, window openings field plated, as in SIP-114 and SIP-115.
  • 4 man crew was used to hand set panels and execute details with assistance of crane.

Results – Walls

  • 4 men spent 9 hours 45 minutes or 39 man hours to set 312 lineal feet of wall.
  • 8 lineal feet of installed R-Control SIP per man hour.
  • 64 square feet of installed R-Control SIP per man hour.

Study 2 Project:

Labor time estimate for installing R-Control SIP wall panels used to build the structural and insulated envelope of a 3652 square foot single story home.

R-Control SIPs:

Panels were supplied from factory: Cut to length, width, and gable configuration. Door and window openings were cut. Spline and plate pockets were factory cut.

Scope of work – Walls

  • 348 lineal feet of 8 ft. high walls – installing 2X plate material in 14 factory cut openings and 9 header openings, top plate.
  • Treated plywood with bottom sill plate, as in SIP-104a.
  • R-Control SIP was set over sill plate, as in SIP-104a.
  • Panel to panel connection was done using surface spline, as in SIP-102.
  • Corner connection was done, as in SIP-103. (16 corners)
  • Door, window openings field plated, as in SIP-114, SIP-115 and SIP-112c.
  • 4 man crew was used to hand set panels and execute details.

Results – Walls

  • 4 men spent 12 hours or 48 man hours to set 348 lineal feet of wall.
  • 7.3 lineal feet of installed R-Control SIP per man hour.
  • 65 square feet of installed R-Control SIP per man hour.

Study 3 Project – Walls:

Labor time estimate for the setting of R-Control SIPs for wall and roof panels used to build the structural and insulated envelope of a 28’ x 22’ structure.

R-Control SIPs:

Panels were supplied from factory: Cut to length, width, and gable configuration. Door and window openings were cut. Spline and plate pockets were factory cut.

Scope of work – Walls:

  • Treated lumber at top of concrete for capillary break, as in SIP-104.

  • Sill plate was installed top of treated plate, as in SIP-104.
  • R-Control SIP was set over sill plate, as in SIP-104.
  • Panel to panel connection was done using block spline, as in SIP-102g.
  • Corner connection was done, as in SIP-103.
  • Door, window openings field plated, as in SIP-114 and SIP-115.
  • 4 man crew was used to hand set panels and execute details.

Results – Walls

  • 4 men spent 3 hours or 12 man hours to set 100 lineal feet of wall.
  • 8.33 lineal feet of installed R-Control SIP per man hour.
  • 84 square feet of installed R-Control SIP per man hour.

Study 3 Project Con’t… – Roof:

Labor time estimate for the setting of R-Control SIPs for wall and roof panels used to build the structural and insulated envelope of a 28’ x 22’ structure.

R-Control SIPs:

Panels were supplied from factory: Cut to length, width, and gable configuration. Door and window openings were cut. Spline and plate pockets were factory cut.

Scope of work – Roof:

  • Preparation of R-Control SIP roof panels on ground, block spline male side installed, as in SIP-102g.
  • Attachment at eave wall, as in SIP-102g.
  • Attachment at gable wall, as in SIP-122c.
  • Attachment at ridge, as in SIP-121a.
  • Eave and gable edge plating, as in SIP-119b and SIP-119d.

Results – Roof

  • Preparation: 2 men spent 1 hour to install 180 lineal ft. of block spline in 4’ wide x 15’ long roof panels, as in SIP-102g.
  • 90 lineal feet of spline per man hour.
  • 2 men on roof, 1 man on the ground, set 900 sq. ft. of roof in 2 hours, 6 man hours, plus 2 man hours prep.
  • 2 hours of crane time.
  • 113 square feet of installed R-Control roof panels per man hour.