Construction Innovations: Engineered Panels in Residential Construction
By Perry A. Tabor, P.E.
As Builder/Architect's structural engineering expert columnist, we continue to feature our monthly "Structural Design Corner," bringing you interesting and useful information, including viable design innovations and alternatives.
Last month, we discussed the integration of one such innovation: manufactured components. This month's article features another innovation: engineered panels. Engineered shear panels have been well received by the industry and have permitted the expansion of architectural freedom in an ever-increasing stringent construction environment.
Over the recent decades, residential customer demands upon architecture has commanded increased window and door sizes in an effort to tie the home interior with the outdoor environment.
In addition, floor plans have seen increased square footage, integration of open floor plans (e.g., great rooms: combination family room, kitchen and dinette), higher plate heights and an increased percentage of two-story units, while parcel square footage has decreased and typical roofing material has changed from asphalt composition or wood shake to heavier concrete tile.
In addition to these significant changes, the seismic code requirements have increased two- to threefold and lumber strength values have decreased during the past couple of decades.
As a result, housing units have become more vertical with reduced lower level interior walls, concrete slabs have been piled on the roof and the walls have more openings than a block of Swiss cheese! All the while, structural demands are increased and material strengths are decreasing.
"We are no longer in Kansas, Toto (1,500 square feet, four-bedroom rancher)" ... welcome to California (3,500 square feet, four-bedroom, three-story townhouse with tuck-under garage overlooking the Calaveras fault).
Fortunately, we've had material innova- tions to assist in addressing these significant changes, such as one introduced by Gary Hardy with the Hardy Frame (wood framing contractor who developed a light-gauge steel engineered shear panel for residential application), which was followed closely with the release of Z-Frame, Simpson StrongWall (light-gauge steel hardware manufacturer who developed a wood-composite engineered shear panel), TJ Panel and, most recently, the Simpson Steel StrongWall to address structural challenges noted above.
Essentially, the above mentioned engineered shear panels will substitute for field-installed plywood shearwalls and associated hardware by providing higher strength capacity with easier installation, as well as provide solutions to narrower wall lengths, taller plate heights and higher lateral shear demands.
There are three very important things to remember when installing engineered panels: get the anchor and holdown bolts installed correctly; get the bolts right; and finally pay attention when installing the bolts.
At foundation construction:
- Ensure the forms are level and true, so that the panel stands plumb when bolted into position.
- Use the manufacturer's bolt template/guide, since the panel bolt hole can not be widened or re-drilled.
- Ensure the bolts are installed plumb, that the bolt diameter matches the panel specified and that length of concrete embedment is achieved (protecting [sleeve or taping] the exposed bolt threads is recommended).
After the bolt installation has been completed, the remaining construction is so simple that even Billy Bob and Joe Bob can easily take over, under the diligent supervision of Spot.
If you would like to see this topic covered in greater detail, please just let us know. Otherwise, we look forward to covering other innovations and topics of interest in future articles.
May 2007 Builder Architect Edition Issue