I practice in an area with extremely high wind demands (170MPH and above) and have always required full height blocking to maintain [highlight #FCE94F]diaphragm boundary nailing[/highlight]. Whether this be through nailed blocking w/plates, or using something like a (Simpson) roof boundary clip, it's always there. It's alarming how often I get push back on this from the contractors.
Having combed through this time and time again, I often go through the following sequence of design aspects and responsibilities. In the end, I consistently end up requiring the full height blocking. For those of you who have solidified your design on an alternate solution, do you mind discussing how you get around requiring full height blocking at truss heels? If you're going to suggest a structurally sheathed hybrid soffit/diaphragm, do you have any industry standards or references to back it up (besides your own manual calculations).
Thought sequence:
[li]For both "blocked" and "Un-blocked" diaphragms, the AWC's SDPWS require nailing at diaphragm boundaries.[/li]
[li]However, prescriptive sections of the IRC provide details to ignore continuity for boundary nailing based on an acceptable truss heel height... in some cases omitting any blocking at all.[/li]
[li]However, truss designers assume loading in the plane of the truss. Truss designs do not account for cross-grain bending.[/li]
[li]The SBCA and Wood Truss Council piggyback on the suggestions of the IRC and go a step further by providing an analytical approach to partial height blocking. They assume manufactured connectors can do the trick.[/li]
[li]However, manufacturers' like Simpson do not warranty connectors to replace diaphragm boundary members or prevent cross grain bending.[/li]
[li]GC's claim, "in all their years of building, they never had to do it that way." They also want cost savings.[/li]
[li]Architects are more concerned about ventilation issues... v-notching, blocking holes, blocking every other bay, etc. (rightfully so).[/li]
[li] The building designers must connect the dots and takes responsibility for the truss bracing and load path continuity.[/li]
What am I missing here?
Having combed through this time and time again, I often go through the following sequence of design aspects and responsibilities. In the end, I consistently end up requiring the full height blocking. For those of you who have solidified your design on an alternate solution, do you mind discussing how you get around requiring full height blocking at truss heels? If you're going to suggest a structurally sheathed hybrid soffit/diaphragm, do you have any industry standards or references to back it up (besides your own manual calculations).
Thought sequence:
[li]For both "blocked" and "Un-blocked" diaphragms, the AWC's SDPWS require nailing at diaphragm boundaries.[/li]
[li]However, prescriptive sections of the IRC provide details to ignore continuity for boundary nailing based on an acceptable truss heel height... in some cases omitting any blocking at all.[/li]
[li]However, truss designers assume loading in the plane of the truss. Truss designs do not account for cross-grain bending.[/li]
[li]The SBCA and Wood Truss Council piggyback on the suggestions of the IRC and go a step further by providing an analytical approach to partial height blocking. They assume manufactured connectors can do the trick.[/li]
[li]However, manufacturers' like Simpson do not warranty connectors to replace diaphragm boundary members or prevent cross grain bending.[/li]
[li]GC's claim, "in all their years of building, they never had to do it that way." They also want cost savings.[/li]
[li]Architects are more concerned about ventilation issues... v-notching, blocking holes, blocking every other bay, etc. (rightfully so).[/li]
[li] The building designers must connect the dots and takes responsibility for the truss bracing and load path continuity.[/li]
What am I missing here?
