COLUMN BUILDING SCIENCES PHOTO 1 Pea gravel-crushed stone perimeter pestresistant ground break. PHOTO 2 Pea gravel-crushed stone perimeter pestresistant ground break. PHOTO 3 Concrete skirt perimeter pest-resistant ground break. PHOTO 4 Concrete skirt perimeter pest-resistant ground break. perimeter concrete paver ground break. The concrete paver should be set on a 4 in. (102 mm) thick sand layer. The concrete paver ground break should slope away from the building at approximately 5% (½ in./ft [0.04 mm/m]). One of the worst pests are termites. Termites are a major threat to the structural integrity of homes. Here is something obvious-most damage to buildings caused by termites can be avoided by preventing the entry of termites where buildings are connected to the ground. Although obvious, we do dumb things and then try to rely on inter-species chemical warfare to compensate for our dumbness. Let me repeat the obvious-preventing the entry of termites into the building is the first best strategy. More specifically, prevent the entry of termites into and through basement foundations, crawlspace foundations and slab-on-grade foundations: * Provide termite shields between foundations and framing; * Provide inspection ability; and * Seal foundation service penetrations. Additionally, homes can be constructed with termite-resistant 52 ASHRAE JOURNAL ashrae.org materials such as borate-treated lumber framing and insulations or inherently termite-resistant materials such as mineral wool insulation. Borate-treated lumber framing materials must be protected from liquid water to prevent leaching of the borate treatment. Exposed treated lumber framing will lose its efficacy over time. Borated-treated lumber framing should not be exposed to rain and should not be used in ground contact or below grade. Borate-treated lumber framing is recommended for use in " heavy " termite-infestation regions. Such regions are defined in the 2018 International Residential Code (IRC) in Figure R301.2(7), " Termite-Infestation Probability Map " (Figure 5). Borate-treated cavity insulations such as cellulose are not likely to be exposed to rain and therefore present very little risk from leaching of the borate treatment and are also recommended in heavy termiteinfestation regions. Inherently termite-resistant cavity insulations such as mineral wool insulation are also recommended. Borate-treated expanded polystyrene (EPS) can experience leaching M AY 2021 PHOTO 5 Concrete paver perimeter pest-resistant ground break. (Photo courtesy of the San Francisco Department of the Environment-Pest Prevention by Design.) when used below grade or in ground contact. However, the EPS can be protected from liquid water leaching with the use of drainage membranes or capillary breaks. In all cases, all ground contact rigid insulations, including borate-treated EPS, should be used in conjunction with termite shields. Borate-treated EPS used above grade as continuous exterior insulation is typically protected by back-ventilated and drained cladding assemblies and present low risk from leaching of the borate treatment.http://www.ashrae.org