Nontoxic Pest Control

Chip Henderson, AIA, CEM, LEED Faculty
August 25, 2012
Nontoxic Pest Control

The LEED for Homes Rating System includes a credit and points for implementing nontoxic pest control measures. Part (a) of SS 5. under Pest Control Alternatives says; “Keep all exterior wood at least 12” above soil.” Depending on how Section R319 of the IRC applies to your project, all wood (siding, sheathing and framing) will (or should) be at least 6 inches and possibly 8 inches above the soil anyway.

To be clear, this 12 inch clearance requirement does not apply to wall framing, sill plates, interior framing, trim, wood floors, etc. and only includes exterior wood (or other cellulosic material) that is directly exposed to soil or air. The wood framing conditions that cause the most difficulty in successfully achieving this credit are: the bottom edge of OSB sheathing, porch posts, and wood stairs and stringers.

Remember to use a thick (3/8”) sill seal between the plate and concrete. Foam sill seals are now available laminated to ‘flashing tape” for added water and air leakage protection. Pretty cool stuff and helps meet Part (c) of this Credit; Include no wood-to-concrete connections, or separate connections with dividers”.  The sill plate should be Borate treated for pest management.  Sill plates are not required (by building codes) to be “Wolmanized.” Or other trade names often applied to a whole list of treatments including; Chromated Copper Arsenate (CCA-C), Alkaline Copper Quat (ACQ-C, ACQ-D, ACQ-D Carbonate), Micronized Copper Quat (MCQ), Copper Azole (CA-B & CA-C, μCA-C). These wood treatments should be limited to exterior or ground contact and avoided inside the home.

So put these conditions on your LEED ID 2.2 Durability Checklist and explore options.