Bracing & Restraint

Question: 

How much OSB can be stacked on a floor deck without damaging the trusses?

Question: 

Manufactured gable ends are actually frames even though they are often referred to as trusses. The webs are “studs” oriented vertically and usually spaced at 12, 16 or 24 in. O.C. The gable end frame is designed to transfer vertical loads from the roof to the continuous bearing wall below. Another way gable end frames are different from trusses placed in the interior of the structure is that frames experience perpendicular wind loads. The sheathed frame transfers the wind loads to the roof and ceiling diaphragms and vice versa.

Question: 

I am looking for strongback bracing requirements for a 12 in. deep residential floor system with trusses in lengths up to 19 ft. Can the strongback bracing end at a truss without tying into an end wall? For instance, can three trusses of a type be tied together by strongbacks, then the next series of different trusses be tied together without having to be tied back to the previous type of trusses?

Question: 

Some building designers believe that gable end webs need to be L-braced to 90% of the web length, which sounds fine. However, they spec that scissors gable end webs need to be braced to 100% of the web length. That means that in the field they are notching the braces to fit around top and bottom chords – you can imagine how difficult that can be. Is that necessary or even the intent of the web L-bracing?

Question: 

As a forensic engineer who has investigated numerous collapses of wood truss systems, I find your web site an excellent resource on the proper erection of wood trusses. What are your opinions on steel trusses, particularly with regards to installation and bracing? Do you feel that the installation and bracing techniques utilized for wood trusses are applicable to steel trusses? Do you know if that is the general industry standard or are there specific requirements and guidelines for steel trusses? Is there a particular guideline/commentary available for metal trusses?

Long span trusses can pose significant risk to installers. The dimensions and weight of a long span truss can create instability, buckling and collapse of one or many trusses, if not handled, installed, restrained and braced properly. As such, they require more detailed safety and handling measures than shorter span trusses. This research report provides guidelines for proper handling and installation of long span trusses for both wood and cold-formed steel.

This presentation provides information on and requirements for the use of metal channel to meet lateral restraint/bracing requirements for metal plate connected wood trusses.

NFC member shares proper bracing in action.

Minimum top and bottom chord permanent lateral restraint/bracing of structural roof or floor trusses is assumed to be adequate when using code-compliant roof and/or ceiling diaphragms. This lateral restraint/bracing is typically accomplished with code-compliant roof /floor sheathing and fastener spacing and/or code-compliant gypsum ceiling material and fastener spacing or purlins at a given on-center spacing.

The Industry Testing Subcommittee is making plans to keep SBCRI busy in the coming year.