Post Frame Ring Shank Nails in NDS!

During a revision of ASTM standard F1667 a few years back, ring shank nails were removed from the standard and were subsequently dropped from recent editions of the National Design Specification (NDS) for Wood Construction. Now, thanks to the work of the NFBA T&R Committee under the lead of Patrick M. McGuire, P.E. and with special effort on his part, the ring shank nails are acknowledged by the American Wood Council of the American Forest & Paper Association, keepers of the NDS.

In a just released update to the NDS in the form of NDS Design Aid No. 4, ring shank nails are making their return to the NDS under the new name of "Post Frame Ring Shank Nails". The design aid contains design values for single shear connections to supplement Table 11N (wood to wood) and Table 11P (steel plate to wood). The design aid can be found at http://www.awc.org/pdf/DA4-RingShank.pdf

The NFBA T&R committee has been prioritizing this issue pretty highly in recent years to not only reinstate the nails as part of the standard but also to re-evaluate the design values that were allowed for these nails, believing that specific testing and research will result in more accurate and higher allowable loads for both shear and withdrawal values for use in design.

So, although this release of Design Aid No. 4 is a significant step, the design values it contains are limited to shear values only and these are not significantly higher than a similarly sized common nail. Testing currently being performed for the NFBA should provide the basis for justifying higher allowable shear loads and also the withdrawal values in future editions of the NDS.

BCSI - Guide to Good Truss Practices

The latest Building Components Safety Information (BCSI) book was published in October of 2006 and should be familiar to all contractors, builders, and designers using Metal Plate Connected (MPC) Wood Trusses. At the 2007 National Frame Builders Expo in Indianapolis, I gave a presentation with Brent Leatherman of TimberTech Engineering in which I stressed the importance of this document and the specific recommendations in BCSI-10 which are specific to Post Frame buildings.

The Subtitle is descriptive and accurate: "Guide to Good Practice for Handling, Installing, Restraining & Bracing of Metal Plate Connected Wood Trusses." The BCSI offers many diagrams and photos to illustrate the concepts and guidelines outlined in the text.

The document is available for order ONLINE for $10.20/book or less, depending on quantity ordered and your membership status with the Truss Plate Institute (TPI) or Wood Truss Council Association (WTCA).

This document does not have the force of the building code behind it, but it does create an accepted level of care within the industry which could be used in the event of litigation when bracing, handling, installation or restraint of trusses are involved. Having said that, however, I have heard of some building officials enforcing this guide within their jurisdictions as if they were part of the enforceable code, all the more reason to be familiar with this document!

I have created a new post category ("Wood Trusses") for this entry since I intend to write more about different aspects of this topic, including lifting guidelines, temporary bracing requirements, and permanent bracing practices. If you have any subjects you'd like to see explored here, please let me know!

Construction Hiring Jumps in March 2007

This appears to bode well for the commercial building industry, as reported at SBC Magazine's web site:

Construction hiring jumps; A/E activity suggests more to come; Transportation Costs Down

Nonfarm payroll employment, led by a 56,000-job jump in construction, rose 180,000 in March, seasonally adjusted, the Bureau of Labor Statistics reported today. The construction gain nearly reversed a weather-aggravated drop of 61,000 in February. Since March 2006, total employment climbed 1.4%, compared to 0.3% for construction employment. But nonresidential employment (nonresidential building, specialty trades, and heavy and civil engineering), added 146,000 jobs or 3.4%, more than double the overall nonfarm rate, while residential building and specialty trades shed a combined 129,000 jobs or 3.6%.

Architectural and engineering (A/E) activity, a precursor for nonresidential construction, remains positive. A/E employment rose 57,000 (4.2%) over 12 months, BLS reported. The American Institute of Architects (AIA) reported on March 23 that its index of billings at 300 architectural firms slipped in February but remained above neutral. “Growth in the commercial/industrial and institutional sectors fell slightly this month, but remains elevated overall,” AIA Chief Economist Kermit Baker commented. As for residential billings, “The score indicates that the sector is no longer in freefall, but instead has moderated to a more stable level.” Total revenue of A/E and related services firms rose 1.6% in the fourth quarter, up from a 0.9% gain in the third quarter, the Census Bureau reported in a March 14 release on quarterly revenue for selected services (www.census.gov/qss).

For the rest of the article, please see the SBC web site here.