Sometimes, easier is better.
Builders complain of a lack of information on how to connect cold-formed steel (CFS) frame assemblies and structures to insulating concrete form (ICF) exterior walls in the construction of single-family homes. Many builders say that the methods they use are overly involved and expensive. However, many are also unwilling to employ simpler methods for fear that connections might be inadequate.
Key Findings:
The common connections between cold-formed steel framing and insulating concrete form walls are:
- CFS interior walls to ICF exterior walls
- CFS floor decks to ICF exterior walls
- CFS roof structures to ICF exterior walls
- Upper-story CFS exterior walls to lower-story ICF exterior walls
This guide recommends specifications for alternative connection methods that are economical and reliable. Note that application of this information to a specific project or setting should be reviewed by a qualified professional.
Recommendations:
Non-loadbearing interior CFS walls in many cases require no connection to the ICF exterior wall. Where the interior wall will be subject to high lateral forces or vibrations, a simple fastener to the ICF wall or some form of plate fastened to the ties is recommended.
CFS floor decks include ledger tracks to which the joists are fastened. These tracks may be fastened to the ICF exterior wall with anchor bolts or right angle ledger connectors. Within specified limits, the joists may be fastened to the tracks directly with self-tapping sheet metal screws. The end joists of CFS floor decks should be attached to the side walls of the building using anchor bolts.
Several floor systems create floor decks using steel and concrete components. This document also provides general descriptive information for such systems.
CFS roof members (trusses or joists and rafters) may be connected to the ICF walls directly with embedded steel straps. Alternatively, they may be connected to a top plate with steel connection plates, and the plate may be connected to the ICF walls with embedded steel straps. As a third alternative, roofing members may be connected to the ICF wall directly with anchor bolts adhered into special holes drilled in the concrete after the concrete has cured.
The end roof members can be connected to the ICF side walls at various intermediate points. This may be accomplished using any of the same three methods that the other roof connections are made.
Upper-story CFS exterior walls may be connected to lower-story ICF exterior walls with anchor bolts through the bottom plate of the CFS wall.
Among the informative tables are:
Table 2.1, Applicability Limits (page 5).
Table 3.2, Cold-formed Steel Member Sizes (page 20).
Table 3.3, for minimum thickness of cold-formed steel members (page 22).
Table 4.1, for lateral velocity pressure for determination of ICF-to-floor connection requirements (page 38).
Table 7.1, for lateral velocity pressure for determination of ICF-to-steel roof connection requirements (page 63).
