T&G Decking as diaphragm
T&G Decking as diaphragm
(OP)
Local code official is asking me to submit any research showing the ability of T&G heavy timber decking to act as a roof diphragm.
SBC 2000 says not to use interlocking pieces as diaphragm. However, we are spiking each piece together. We have always used it in the past.
Has anyone ever used spikes to resist the horizontal shear and/or know of any research showing diaphragm using T&G decking.
THanks!!
SBC 2000 says not to use interlocking pieces as diaphragm. However, we are spiking each piece together. We have always used it in the past.
Has anyone ever used spikes to resist the horizontal shear and/or know of any research showing diaphragm using T&G decking.
THanks!!






RE: T&G Decking as diaphragm
Is anyone familiar with methods of using 3x TNG decking as a diaphragm? Shorting of putting plywood on top of or under it and nailing that to the boundaries as the diaphragm, I don?t see any obvious and code compliant route to take. I could envision 3x being a very capable diaphragm with toe nailing or gluing, in theory? but I don?t see a lot of glued assemblies in the code. Anyone have any experience with this?
Paul,
I have a barely ledgible fax from 1997 (still on the old thermal fax paper) regarding the design of diaphragms using laminated timber decking. The fax was from the Filler King Co (now Lock Deck by the Disdero Lumber Co., try www.lockdeck.com) and was originally written by Robert Hoyle, Jr., P.E. while he was at the Potlach Co. The fax details how to design laminated timber diaphragms and makes reference to ICBO Report No 1379. Mr. Hoyle also has a book, Wood Technology in the Design of Wood Structures which includes detailed design examples. I hope this helps. I can try to xerox the info I have; but, I doubt you would ever be able to read it.
Brian K. Smith, P.E
RE: T&G Decking as diaphragm
For more information contact Gunnar Brink at Disdero Lumber, 503-239-8888.
If you are dealing with 2" deck gluing is probably not an option because the small size of the deck don't allow you to develop an adequate glue bond.
Regarding nailing of the deck, you are some what on your own. Nailing the deck will increase the diaphragm capacity the problem is how effective it will be. With your Building Official you should be able to submit design calculations to justify your approach.
The major problem you have with this approach is that the lateral deflection of the diaphragm may be larger than you predict. You could contact the technical department at Western Wood Products Association for more information.
Also there are a large number of timber buildings in the field with only 2" decking bracing them, which have performed adequaetly over time.
One final thought, based on my experience, is that the cost of glue and labor involved in gluing the deck up to perform as a diaphragm ussually exceeds the cost of a plywood overlay. You might check on your next project what the additional labor cost are for specifing the additional nailing
RE: T&G Decking as diaphragm
Building codes also allow you to calculate diaphragm capacities by principles of mechanics using values of fastener strength and sheathing shear resistance. In my experience, this is rarely done though because allowable capacities are tabulated for many common diaphragm types.
RE: T&G Decking as diaphragm
Nonetheless I seem to recall having to overlay plywood over T&G to get high shear values when I couldn't get enough capacity.
See the OLD '88 UBC 2513a You can fly right with this if you have a diagonal controlled random layup. Or else, rational analysis can apply. I've done the calcs RARSWC ands Taro refer to as last resorts.
RE: T&G Decking as diaphragm
I know you asked this question a while back.. What did you find as a solution?
RE: T&G Decking as diaphragm
RE: T&G Decking as diaphragm
RE: T&G Decking as diaphragm
RE: T&G Decking as diaphragm
RE: T&G Decking as diaphragm
RE: T&G Decking as diaphragm
<http://www.awc.org/pdf/wcd2.pdf>