In addition to allowable lumber stress limitations, parallel chord truss designs are also regulated by maximum permissible deflection-to-span and depth-to-span limitations. All of the following recommended limitations should be achieved to provide a quality roof / floor system and assure...

A Truss Design Drawing (TDD) includes specific information[1] for structural engineers and building designers: truss profile, plates, loadings, wind speed, codes, enclosure, exposure, reactions, deflections, materials, bracing, bearings, etc. The maximum reactions are the most important values...

For more than 70 years, people have been using machines to assist in the grading of lumber. This article summarizes the machine grading methodologies for producing Machine Stress Rated Lumber (MSR) and Machine Evaluated Lumber (MEL) and highlights the similarities and differences between MSR and...

On a recent Quality Assurance Audit at a large facility, we witnessed a floor truss builder carefully spacing out his floor truss webs in the allotted space available with precision and care. He was very meticulous. I asked him why he was doing that and he explained that his in-house inspector...

As discussed in last month’s article, “Addressing the Roof Truss Design Note: 'Provide adequate drainage to prevent water ponding.’,” by Frank Woeste and Scott Coffman, ponding is an issue not always addressed adequately. Ponding is a design issue, a mishap, or an...

The purpose of this article to examine the significance and implementation of a typical note that appears on metal plate connected roof-truss drawings when a top-chord-pitch of ¼:12 or less is specified by the Construction Documents. Three questions will be addressed: What is the...

Introduction Custom kitchens, with high-end appliances, granite countertops, and central islands, are becoming more and more prevalent in the home market today. These products and finishes are heavy and the dead loads from the central islands and/or cabinets positioned along interior...

Two kinds of designers are involved in home construction—design professionals responsible for the structure and the interior-focused designers responsible for the final appearance. Although these roles can overlap, it is important for design professionals to be aware of in-service demands...

Understanding construction loading is important as it relates to the acceptable practices in terms of staging and storing construction materials prior to installation. What does “construction loading” mean? This term describes materials and people that are present during the course...

The knowledge we take for granted today on MSR lumber is due in large part to the pioneering work of Professor Robert Hoyle, P.E. In the early 1960s at Potlatch Forest, Inc., he conducted basic research on the relationship between stiffness and strength of lumber, paving the way for the MSR...