U.S. Department of Energy U.S. Department of Energy Energy Efficiency and Renewable Energy

Structural Insulated Panels (SIPs) Seams

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All seams between structural insulated panels (SIPs) foamed and/or taped per manufacturer's instructions

Scope


Air Sealing

 

All seams between Structural Insulated Panels (SIPs) foamed and/or taped per manufacturer’s instructions.

  1. Apply manufacturer-approved sealant inside the joints of all panels and at sub-floor or foundation connections.
  2. When applying tape to walls, center on joints and provide overlap of tape to meet manufacturer’s specifications.
  3. When applying tape to roof panels, start from the lowest point of the panel and continue upward.

Description


SIPs consist of two layers of plywood or OSB that “sandwich” an inner core of insulating rigid foam. Panels are spliced together using splines, consisting of strips of OSB, SIPs, or 2x4 or 2x6 lumber. The seams where one panel joins another are susceptible to air leakage. To form an air tight bond, spray foam or caulk is applied to the seams before the panels are connected. Many SIP manufacturers will provide the caulk and instructions. The wall-floor, wall-wall, and wall-roof seams can each require as many as six beads of caulk, and the roof ridge seam can require up to 8 beads of caulk.

 

After caulking, the panels are fit together to assemble the structure. To ensure that joints lock tightly together, a belt winch can be used to pull wall assemblies together; this is especially helpful with larger panels. Before drywalling, the seams can be covered with peel and stick tape as a second layer of protection against air leakage. Before installing drywall is also an ideal time to test the air tightness of the seams with a blower door test and smoke pencil to visually identify the location of any leaks.

 

Air barrier effectiveness is measured at the whole-house level. High-performance branding programs and the 2009 International Energy Conservation Code (IECC) require that builders meet specified infiltration rates at the whole-house level. See the “compliance” tab for these specified infiltration rates.

 

For more information on SIP installation, see Structural Insulated Panels.

 

 

How to Seal SIP Seams

1. Connect the panels with splines. The three most common splines are surface splines, insulated splines, and structural spines (see Figures 1, 2, and 3). To minimize thermal bridging, only use structural splines when needed to carry the structural load. Splines can be installed on one side of the panel in the factory; this can save assembly time at the site.

 

 

 

A surface spline reduces thermal bridging much more than a structural spline at SIP panel seams

Figure 1 - A surface spline reduces thermal bridging much more than a structural spline at SIP panel seams. Reference

 

 

 

 

An insulated spline is another option for avoiding thermal bridging at SIP panel seams

Figure 2 - An insulated spline is another option for avoiding thermal bridging at SIP panel seams. Reference

 

 

 

 

A structural spline made of a solid 2x is used where needed to meet structural load requirements at SIP panel seams

Figure 3 - A structural spline made of a solid 2x is used where needed to meet structural load requirements at SIP panel seams. Reference

 

 

2. Caulk on each side of the spline. Use caulk from the manufacturer, if provided. Follow the caulking schedule required by the SIP manufacturer for the number of beads of caulk to use at each type of seam. Make sure the beads are continuous. Consider using a power caulker; even in a small (1,200 sq. ft.) home, the amount of caulk required can total over 5,000 lineal feet of caulk.

 

3. Assemble the walls and roof. Use a fork lift and crane to place panels. Use lift plates and a belt winch (available from the manufacturer) to pull panels together tightly, if needed (Figure 4).

 

 

 

Lifting plates attached to the wall provide good bracing to tighten up SIP panel seams

Figure 4 - Lifting plates attached to the wall provide good bracing to tighten up SIP panel seams. Reference

 

 

 

4. Install peel-and-stick tape at panel-to-panel seams and at the ridge and wall-roof interface (See Figure 5).

 

 

Peel-and-stick panel tape provides added assurance that SIP panel seams will remain airtight

Figure 5 - Peel-and-stick panel tape provides added assurance that SIP panel seams will remain airtight. Reference

 

 

5. Prior to drywalling, conduct a blower door test and use a smoke pencil to ensure that panel seams are tight (Figure 6).

 

 

 

Use a smoke pencil to check for air leaks at SIP panel seams, especially along the ridge beam

Figure 6 - Use a smoke pencil to check for air leaks at SIP panel seams, especially along the ridge beam. Reference






Ensuring Success


The air tightness of the envelope assembly of a home constructed with structural insulated panels can be easily tested by conducting a whole-house blower test prior to dry wall installation. While the house is depressurized, inspect all panel seams with a smoke stick. An infrared camera may also be helpful in spotting air leakage, if a sufficient temperature difference exists between the outside and the inside of the home. 



Climate


No climate specific information applies.



Right and Wrong Images



Presentations

None Available



Videos

None Available




CAD Images




Compliance


ENERGY STAR Version 3, (Rev. 6)

Thermal Enclosure Checklist, Air Sealing. Cracks in the building envelope fully sealed. All seams between Structural insulated Panels (SIPs) foamed and/or taped per manufacturer’s instructions

DOE Challenge Home

Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3

2009 IECC

The 2009 IECC does not specifically address sealing SIP seams. Table 402.4.2 Air Barrier and Insulation Inspection Component Criteria, Walls: Corners, headers, narrow framing cavities, and rim joists are insulated.*

 

2009 IRC

The 2009 IRC has several diagrams in Section R613 Structural Insulated Panel Wall Construction that illustrate the placement of continuous sealant. 

2012 IECC

The 2012 IECC does not specifically address sealing SIP seams. Table R402.4.1.1 Air Barrier and Insulation Installation, Walls: Junction of foundation and wall sill plates, wall top plate and top of wall, sill plate and rim-band, and rim band and subfloor are sealed. Corners, headers, and rim joists making up the thermal envelope are insulated.*

 

2012 IRC

The 2012 IRC has several diagrams in Section R613 Structural Insulated Panel Wall Construction that illustrate continuous sealant. Table N11402.4.1.1 Air Barrier and Insulation Installation, Walls: Junction of foundation and wall sill plates, wall top plate and top of wall, sill plate and rim-band, and rim band and subfloor are sealed. Corners, headers, and rim joists making up the thermal envelope are insulated.*

 

 

*Due to copyright restrictions, exact code text is not provided.  For specific code text, refer to the applicable code.



Case Studies

None Available


References

  1. 2009 IECC—International Energy Conservation Code

    2009 IECC, International Energy Conservation Code. International Code Council, Washington, D.C.

  2. 2012 IECC—International Energy Conservation Code

    2012 IECC, International Energy Conservation Code.  International Code Council, Washington, D.C.

  3. Builders Guide to Structural Insulated Panels (SIPs) for all Climates

    Lstiburek, J. 2008. Builders Guide to Structural Insulated Panels (SIPs) for all Climates. Building Science Corporation.

  4. Builder’s Guide to Structural Insulated Panels (SIPs)

    Lukachko, A. 2009. Builder’s Guide to Structural Insulated Panels (SIPs). Presented at the SIPA Annual Meeting, 2009, Building Science Corporation.

  5. Building with Structural Insulated Panels

    Morley, M. 2000. Building with Structural Insulated Panels. The Taunton Press Inc.

  6. DOE Challenge Home National Program Requirements

    DOE. 2012. DOE Challenge Home National Program Requirements (Rev. 02). Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy, Washington, D.C.

  7. ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements

    EPA. 2012. ENERGY STAR Qualified Homes, Version 3 (Rev. 06) Inspection Checklist for National Program Requirements. U.S. Environmental Protection Agency, Washington, D.C.

  8. How to Build a Zero Electric Utility Cost House

    Christian, J. 2006. How to Build a Zero Electric Utility Cost House. Proceedings of the ACEEE Summer Study, August 2006.

  9. Simple Affordable Near Zero Energy Habitats

    Christian, J. 2004. Simple Affordable Near Zero Energy Habitats. ASHRAE/DOE Thermal Performance of the Exterior Envelope of Buildings, Conference IX, Clearwater Beach, FL, December 5-10, 2004.

  10. Structural Insulated Panel Connection Details

    Structural Insulated Panel Association (SIPA). 2011. Structural Insulated Panel Connection Details. Structural Insulated Panel Association.

  11. Thermal Enclosure System Rater Checklist Guidebook

    EPA. 2011. Thermal Enclosure System Rater Checklist Guidebook. U.S. Environmental Protection Agency, Washington, D.C.



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