In the 1960s, Ed Ryan set basic standards for panelizing walls, and for decades his homebuilding company (now NVR Inc.) followed his lead. His standards also made it easy for us to provide his wall panel equipment. The name we gave it, “Panel-Rite,” would have pleased Ed, since he believed that framing exclusively 8 foot tall walls with 16” on center studs was the right way to panelize. Taller walls, special blocking, and non-standard junctions needed to be added in the field. Jim Ryan even further “skinny-ed down” his brother’s panels in his Ryland Homes product, removing every extra stud he encountered. As long as Ed and Jim kept their framing crews busy, all was well – even though these crews needed skilled carpenters to finish the framing. That was then . . .
Now, 50 years later, framers effectively have shifted much of their field work into the panel shop, compelling suppliers like NVR, Toll, and BFS to build balloon and rake panels, include tub and cabinet blocking, and any assembly that will endear them to the framers. Panel shops have little automation with which to address the complexity (see “Panelization Automation” in July 2017’s Component Advertiser). As Gus Pearson at BFS says, “We’re building the entire house in our plant.” Today’s panel designers face a task arguably more complex than truss designers (see displayed panel elevations), as they must consider:
1. Architectural Details
- Not just bearing wall locations, but all interior dimensions
- Code required clearances in bathrooms, halls, stairs, landings, etc.
- Opening sizes depend on door and window supplier, often an afterthought, requiring repairs
- If rough opening too small, header will often need to be replaced
- If rough opening too large, entire opening must be furred out
- Egress windows require lower sills and minimum opening sizes
- Code required wall bracing which may require portal frames and pre-fab shear panels
- Elevations in conflict with floor plans
- First and second floor windows not in exact vertical alignment
- Windows not centered or symmetrically spaced
- Options drawn exclusively in plan view, without accompanying elevations
2. Structural Requirements
- Transferring girder and header loads to foundation – LVL vs. stacked stud capacities
- “Simplified” APA wall bracing which may require portal frames and pre-fab shear panels
- Stud size and spacing for tall walls and multi-story applications
- Backing for wall connections to foundations and studding for steel rods (Zone 4 tie-downs)
3. Framer/Builder Preferences
- Sheathing/energy code compliance
- Junction types and sheet rock backing
- Terminology
Since wall panel designs are prescriptive (derived from the building code), the builder and his EOR/building designer should provide guidance on many of the above details. Written verification of exact opening sizes should be provided by the builder. Extensive checklists encompassing the above items should be reviewed with the buyer and entered into software defaults for repetitive jobs.