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Author Message David Axt, AIA, CCS, CSI Senior Member Username: david_axt Post Number: 1281 Registered: 03-2002 Posted on Wednesday, February 15, 2012 - 08:04 pm:    I noticed recently that MasterSpec Section 061000 - Rough Carpentry has language that states: "Do not use inorganic boron (SBX) for sill plates." I wonder why when borate treated wood is acceptable for concealed locations? Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 458 Registered: 10-2007 Posted on Thursday, February 16, 2012 - 12:01 am:    My understanding is that borate will do the job as long as the borate is there. The problem is thatif borate treated lumber is exposed to the weather water will leech the borate away thus leaving the wood untreated. In beneral lumber in interior and concealed locations is not subject to the water. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1364 Registered: 03-2002 Posted on Thursday, March 08, 2012 - 04:40 pm:    The sill plate sits on masonry, which is presumed to contain some moisture. As Mark points out, moisture can leach the borate from the wood. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 461 Registered: 10-2007 Posted on Thursday, March 08, 2012 - 06:27 pm:    My understanding is that the concern is not with the moisture in the wood but rather water from the weather of other similar source. I do not believe that changes in humidity will normally be enough to cause the problem. If the moisture in the wood was enough to cause a problem then borate would never be appropriate. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1366 Registered: 03-2002 Posted on Monday, March 12, 2012 - 04:46 pm:    Yes. I meant that there could be moisture in the masonry that affects the wood. Although, other papers I've read indicate that the moisture must be, in a sense, flowing. However, I would avoid it in this condition anyway. Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 1249 Registered: 07-2002 Posted on Monday, March 12, 2012 - 05:19 pm:    yes, the Masterspec assumption is that a sill plate can be subject to a variety of wetting conditions, including sitting in water. (you never know what someone is going to do with their building. ) therefore, because borate is water soluble, it is not a good option for that condition. Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 462 Registered: 10-2007 Posted on Monday, March 12, 2012 - 06:13 pm:    My understanding is that borate treatment is not appropriate when subject to rain and flowing water. Some conditions of extreme condensation might also be a concern. I would not normally be concerned about interior uses. with the possible exception of shower rooms and kitchen where they wash down the floor regularly. Engineers like borate because they do not have to be concerned about the corrosion of fasteners amd metal hardware. If the architect has an opinion on this he should coordinate with the structural engineer. Steven Bruneel, AIA, CSI-CDT, LEED-AP Senior Member Username: redseca2 Post Number: 327 Registered: 12-2006 Posted on Tuesday, March 13, 2012 - 12:29 am:    Mark, would specifying stainless steel hardware eliminate the problem with borate? Mark Gilligan SE, Senior Member Username: mark_gilligan Post Number: 463 Registered: 10-2007 Posted on Tuesday, March 13, 2012 - 12:49 am:    The problem is not with borate but with the chemicals used to treat wood if borate is not used. Most of the chemicals used to treat wood to prevent rot and termites will have a corrosive affect on the steel fasteners and hardware. In those situations Type 316 stainless steel is one of the strategies. John Bunzick, CCS, CCCA, LEED AP Senior Member Username: bunzick Post Number: 1368 Registered: 03-2002 Posted on Thursday, March 22, 2012 - 11:28 am:    However, stainless steel hardware may be appropriate for the copper-quat treated wood treatments. These can attack ferrous metal when water is present. Borate is not known to have the same corrosive effect as copper-quat, but it will leach out in the presence of water as it remains soluble, and does not bind to the wood as do other treatments.