Fire treated blocking

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Author Message Wayne Yancey Senior Member Username: wayne_yancey Post Number: 211 Registered: 01-2008 Posted on Friday, June 12, 2009 - 12:45 pm:    I do not think it applies to wood blocking, nailers, curbs, and cants unless you come across an anal AHJ. This makes no sense when foam plastic insulation is permitted Fire retardant treated wood is permitted in: Roof construction where all the conditions indicated below apply: -girders -trusses -framing -dcking Conditions: The building must be one of the following -Type 1 Construction less than or equal to 2 stories -Type 1 Construciton greater than or equal to 2 stories with the following conditions -Roof must be greater than or equal to 20 feet above top floor -Type II Construction Mark Gilligan SE, CSI Senior Member Username: mark_gilligan Post Number: 163 Registered: 10-2007 Posted on Friday, June 12, 2009 - 01:39 pm:    As I try to interpret section 603.1 I get confused. Section 603.1 gives permission to use, but does not require, non-fire-retardant wood but then item 1 lists some situations where fire-retardant wood is permitted. It would seem that this item is either redundant or that because it says that fire retardant wood shall be permitted it was infering that it is permissible not to use fire-retardant wood. I think I need to read Alice's conversation with the Mad Hatter in Alice in Wonder Land for clarification. The language in the exception under item 1.3 similarly does not make sense in the context. Some structural facts regarding fire-retardant wood: The fire-retardant treatment reduces the strength of the wood and the amount of the reduction is dependant on the type of treatment used. This needs to be coordinated with your structural engineer. Fire-retardant treatment of wood creates the potential for enhanced corrision of metal in contact with it. Manufacturers of wood treatment products generally have recommendations regarding corrosion of metal. Manufacturers of metal connectors such as Simpson Strongtie have recommendations on corrosion protection of their products. In some conditions stainless steel fasteners may be recommended. Here again work with your structural engineer. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1055 Registered: 03-2002 Posted on Friday, June 12, 2009 - 01:50 pm:    I believe that fire-retardent wood is still considered combustible, which may explain some of the confusion. The permissible use of it for roof construction is in a structural capacity, not for blocking which is non-structural. I've never used fire-retardant wood for roof blocking. I used to specify preservative-treated, but due to the use of high-copper-content treatments which may corrode fasteners or steel deck, I have switched to naturally decay-resistant species as identified by the US Forest Service or FM. Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 761 Registered: 03-2003 Posted on Friday, June 12, 2009 - 01:51 pm:    Mark: Section 603.1 permits the use of "combustible materials" in those construction types which require only noncombustible materials. What combustible materials are permitted are stipulated in in items 1 through 22. Section 603.1 does not permit the use of non-fire-retardant-treated wood because it restricts the materials by stating "in the following applications"--if it isn't provided in items 1 through 22 then it isn't permitted. The exception to item 1.3 restricts the use of FRTW in Type I buildings if higher than two stories and the distance from the upper floor to the roof is less than 20 feet. Ron Geren, AIA, CSI, CCS, CCCA, SCIP www.specsandcodes.com Ronald L. Geren, AIA, CSI, CCS, CCCA, SCIP Senior Member Username: specman Post Number: 762 Registered: 03-2003 Posted on Friday, June 12, 2009 - 01:53 pm:    John: You are correct--FRTW is still considered a combustible material. Ron Geren, AIA, CSI, CCS, CCCA, SCIP www.specsandcodes.com Mark Gilligan SE, CSI Senior Member Username: mark_gilligan Post Number: 164 Registered: 10-2007 Posted on Friday, June 12, 2009 - 03:06 pm:    Thanks. The fact that FRTW is considered combustible is the critical insight. Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 879 Registered: 07-2002 Posted on Friday, June 12, 2009 - 03:15 pm:    check also with your ahj. In the Seattle market, the Building Department used to require fire treated blocking on the roof, even though we all "knew" that it would turn into a pile of sawdust in three years. (I finally switched to non-wood blocking in that condition); you may have an equally unknowledgeable Authority, so you'll have to do what they require even if it doesn't make any sense. Ralph Liebing, RA, CSI Senior Member Username: rliebing Post Number: 998 Registered: 02-2003 Posted on Friday, June 12, 2009 - 03:56 pm:    Ms. Whitacre, what material[s] provided the "non-wood" blocking"? More than one product?