Increasing attention is being paid to energy efficiency and interior comfort. In light of that trend, how do I insulate the Simpson Strong-Tie Steel Strong-Wall® panel?

The Simpson Strong-Tie Steel Strong-Wall® panel is a critical life-safety component that can be insulated like other wall cavities. U-factors for various types of insulation are listed in Table 1 below. Lower U-factors can be achieved with additional layers of exterior rigid insulation.

The values in the table are higher than the prescriptive U-factors for my climate zone outlined in the International Energy Conservation Code, the International Residential Code, and the International Building Code. How do I meet code?

Residential: There are several ways to meet the IECC/IRC with the Simpson Strong-Tie Steel Strong-Wall® panel. Any type of insulation that fills the interior and exterior cavities without being compressed may be used to meet the R-value prescriptive method, which requires a certain thickness of insulation in each climate zone. The U-factor method may be met with the addition of rigid insulation inside or outside the wall; its thickness depends on the climate zone and type of insulation used. Finally, the published U-factors may be used as inputs to either the UA or performance methods. Since the Simpson Strong-Tie Steel Strong-Wall® panel is a life safety component, check with your local Building Department to determine if other practices are acceptable.

Commercial: There are several ways to meet the IECC/IBC with the Simpson Strong-Tie Steel Strong-Wall® panel. Any type of insulation that fills the interior and exterior cavities without being compressed may be used to meet the R-value prescriptive method, which requires a certain thickness of insulation in each climate zone and for different occupancy types. The U-factor method may be met with the addition of rigid insulation inside or outside the wall; its thickness depends on the climate zone and type of insulation used. Finally, the published U-factors may be used as inputs for performance-based methods.

How do I meet stricter standards like EnergyStar and LEED?

These standards typically specify a percentage of performance improvement relative to the IECC standard. The U-factors in Table 1 can be used to determine how to insulate the overall building shell to meet EnergyStar, LEED, and other green building standards.

How does the Simpson Strong-Tie Steel Strong-Wall® panel compare to other lateral bracing systems in terms of energy efficiency?

The Simpson Strong-Tie Steel Strong-Wall® panels are designed to minimize losses from conditioned space. First, the cavities allow the full volume of the wall to be packed with insulation. Second, thermal bridging from the corrugated steel element is minimized through separation from both inside and outside of the wall, excluding the top and bottom plates.

TABLE 1.

Insulation Type (Exterior/Interior)	U-Factor (BTU-in/hr-ft2-°F)
	Wall Size
	SSW15X8	SSW18X8	SSW21X8	SSW24X8	SSW24X10	SSW24X12
0/0				0.408
0/Spray Applied Closed Cell Foam		0.19	0.17	0.16	0.16	0.07
0/Spray Applied Open Cell Foam			0.23	0.22	0.22
0/Fiberglass Batts	0.23	0.25	0.22	0.22	0.22	0.10
0/Mineral Fiber		0.28	0.25	0.25
0/Loose Fill Cellulose		0.25	0.23	0.22
Spray Applied Closed Cell Foam/Spray Applied Closed Cell Foam		0.14		0.13
Spray Applied Closed Cell Foam/Spray Applied Open Cell Foam				0.16
Spray Applied Closed Cell Foam/Fiberglass Batts		0.17		0.16
Spray Applied Open Cell Foam/Spray Applied Open Cell Foam		0.20		0.19
Fiberglass Batts/Fiberglass Batts		0.20		0.18

NOTES:

1. A “0” for insulation type indicates no insulation.
2. The SSW is installed so the anchor bolts are visible from conditioned space.
3. Values based on 2x6 framed walls for SSW24x12; all others based on 2x4 walls.
4. Values were calculated using the software program Therm 6.0.
5. Conductivity for materials used are as follows (BTU-in/hr-ft²-°F)
   • Air - Varies
   • Fiberglass Batts – 0.264
   • Loose Fill Cellulose – 0.277
   • Mineral Fiber Insulation (CW90) – 0.347
   • Spray Applied Open Cell Foam – 0.270
   • Spray Applied Closed Cell Foam – 0.140