As energy codes become stricter, builders and designers are seeking options for energy-efficient construction that maintain strength, durability, sustainability and cost-effectiveness. One effective solution is advanced framing, a system of construction framing techniques that optimizes material use and increases energy efficiency. Join APA's Warren Hamrick as he discusses common advanced framing techniques, the benefits of the system and typical challenges that builders encounter during the conversion from traditional framing to advanced framing. This course is approved by AIA (1 HSW/LU) and ICC (0.10 CEU).
Energy efficiency details are not meant to supersede structural code requirements. If a hold down is required in both directions, and if the hold down installation requires two studs, then that trumps the three-stud corner at that location. It is possible that with some coordination during the design phase, hold downs could be located strategically to allow for minimal insulation interruptions.
Installing the wide face of the 2x blocking flat against panel joints in shear walls is a good practice for minimizing intrusion into the insulation within the wall cavity. It is a recognized practice, but it is not a requirement.
The IRC provides prescriptive metal top plate splice requirements in Table R602.3.2. (Note that changes were made to splice plate size and fastening requirements in the 2015 IRC.) It also may be possible to substitute a wood splice using Table R602.3(1) item 13. Any loads outside of the prescriptive nature would need to be evaluated by an engineer for proper splice design.
It probably could be done, but other approaches probably should be considered to meet such an aggressive wall insulation objective. This webinar focused on 2x6 advanced framing that cost-effectively meets both the energy code, as well as the structural requirements of the IRC. That means that insulation levels in a 2x6 wall cavity would be, roughly, in the R19-R23 range. (See Table 3 of APA Form R505, “The Performance Path to Energy Code Compliance.”)
If a client desires a wall R-value of R35 it might be better to consider a double-stud wall assembly, which is used in “super insulation” approaches. Other alternatives would be to use thick continuous insulation or Structural Insulated Panels (SIPS). For more information on SIPS, see APA Product Guide Form H650, “Structural Insulated Panels.”
Absolutely. APA has field staff throughout the United States and Canada. For contact information, visit www.apawood.org and click the “Contact” link at the top of the page. Select, “View Staff Directory” to get the contact information for our Regional Field Service Representatives. You can also call the APA Help Desk at 253.620.7400 for the Field Service Representative who covers your area.
Most of the builders we work with use 1/2” gypsum over 24” stud spacing with no issues, but there are some who prefer 5/8” gypsum. If the thickness of the interior gypsum is increased, it is important to coordinate that with all trades, but perhaps most notably the electrical sub.
There shouldn’t be any issues. That being said, it’s always a good idea to check with your local building department before incorporating changes in a structural assembly. 2x6 framing with 24” oc stud spacing is recognized in the IRC and is understood by most code officials. Some less common details, such as single top plates/stacked framing, may not be as well understood by code officials.
Yes. When stacked or in-line framing is used, the studs, floor joists and roof framing will all be on the same 24” oc layout.
No. APA does not recommend the use of adhesives for fastening wall or roof sheathing to framing, as this can create a situation where over-restrained wood structural panel sheathing is unable to expand into the recommended 1/8” space between panel ends and edges as they take on moisture. Over-restraining panels can increase the likelihood of thinner panels buckling out of plane. Also note that the building code prohibits adhesive attachment of shear walls in high seismic areas, since such rigid connections can fail more suddenly and catastrophically in an earthquake than mechanically fastened connections, which provide a higher level of ductility.
When using the IRC, the wall bracing and other structural provisions must be met. It’s these provisions that may, in effect, impact the amount, size or location of openings.
Our focus was on residential construction per the International Residential Code. If your structure falls outside of the IRC, many of the same details could still be used, but you will need to work with your engineer to confirm.
It’s a matter of preference. The three-stud “California” corner has been more popular over a longer period in the U.S. However, two-stud corners plus ladder blocking (or drywall clips) are also good details. Both the three-stud and two-stud options are covered in the APA Advanced Framing Construction Guide.
When switching to 24” stud spacing, the amount of perimeter attachment locations is no different than studs at 16” oc. There will be a reduction of studs in the field of a 4x8 wall sheathing panel, resulting in fewer fasteners used in the field. There are also no changes required related to wall bracing when using 24” stud spacing. As discussed, if the shear walls have been designed, there are a couple of important footnotes to the shear wall table that need to be checked.
A continuous load path is required by code whether one frames the traditional way or with advanced framing. When the framing is aligned, the vertical (gravity) load path is simplified. However, as I mentioned, many builders opt to stick with a double top plate and do not align the framing through the structure. In that case the load path would be similar to standard framing. The lateral load path is more likely to be impacted by the type of wall sheathing used and how it is fastened, not by the stud spacing or the vertical alignment of the framing.
Wall sheathing fasteners that miss studs can be an issue no matter the stud spacing. The amount of panel perimeter fastening should be the same, whether stud spacing is at 24 or 16 inches. With 24” stud spacing there will be one less stud in the field of a 4x8 foot wall sheathing panel, which can make it more important to be accurate with field nailing.
Wall sheathing fastening in the field of a 4x8 foot panel can impact the performance of a wall with respect to wind pressures acting perpendicular to the building. Related to this, Table R602.3(3) in the 2018 IRC recognizes that wood structural panel wall sheathing can be relied on to resist wind pressures by itself—something that is especially important when lightweight sidings and trim, like vinyl, requires a structural backing, or at gable ends where interior gypsum is not installed. While the fastening requirements in Table R602.3(3) are the same for 24” stud spacing, it should be noted that the ultimate design wind speeds are lower, primarily due to the greater sheathing span.
If the question refers to siding fasteners or fastening of other exterior finish elements into the framing, then using the wood structural panel as a nail base could help alleviate the problem of fasteners missing framing. As long as the correct fasteners and fastener spacing is used with wood structural panel sheathing, it doesn’t matter if siding and trim fasteners miss the studs. Refer to the exterior cladding manufacturer’s recommendations and APA Form Q250, Nail-Base Sheathing for Siding and Trim Attachment.
The single-ply header details are code prescribed per IRC Section R602.7.1. From an engineering standpoint, single-ply headers are best aligned with the outside of the wall. Doing so creates a more direct vertical load path, as well as a more direct lateral load path. However, this is not a requirement of the IRC.
There are several things to take into account when deciding on where to place an efficiently sized window or door header, only one of which is how the moisture performance of the wall might be impacted. Other considerations include numerous structural continuity and constructability considerations.
Because there are multiple sources of potential water intrusion in wall assemblies (not just condensation), it is vital to consider how the wall will dry after it’s wetted. Preventing moisture from entering the wall assembly through proper installation of water resistive barriers, air barriers and proper air sealing techniques, as well as properly locating a vapor retarder suitable for the climate zone, is of primary concern.
No matter the source of moisture (bulk water intrusion from the exterior, air movement or vapor diffusion), APA encourages builders and designers to always provide at least one path for wall assemblies to dry out in case moisture does get in. Providing a drying path, either to the inside of the building and/or to the exterior, should be provided in accordance with recommendations for the climate zone where the building is located. Pay careful attention to the permeability of materials used in the assembly, including the insulation products used. Lower permeability materials can negatively impact the rate of assembly drying. So even if the designer believes that condensation control is of primary importance, an assembly should be designed with a directional drying path for when other types of wetting occurs. All structural, constructability and moisture considerations should be taken into account when determining header location. See APA Form TT-111, “Technical Topics: Wood Moisture Content and the Importance of Drying in Wood Building Systems.”