ASHRAE Journal - May 2021 - 55

COLUMN BUILDING SCIENCES

FIGURE 7 Crawlspace foundation insulated on the interior. The crawlspace is an
unvented conditioned crawlspace. In " heavy " termite infestation regions, boratetreated lumber framing and insulation should be used.

Unfaced Cavity Insulation, Cellulose or
Low-Density Spray-Applied Foam Insulation

Vinyl or Aluminium or
Fiber Cement Siding

Gypsum Board With (Latex) Paint
Rigid Insulation
(Taped or Sealed Joints)

Sealant, Adhesive or Gasket
Sealant at Corner of Bottom
Plate and Subﬂoor or Gasket
Under Bottom Plate

Adhesive
Unfaced Cavity Insulation, Cellulose or
Low-Density Spray-Applied Foam
Sealant
Rodent Protection on
Rigid Insulation

Sill Gasket
Inspection Gap for Termites
Continuous Bead of Sealant

Termite Shield
Set in Mastic

Top Courses Filled Solid
Rigid Insulation (Fire Rated)
(Taped or Sealed Joints)

For Pest Protection Provide
2 ft of Pea Gravel or
Crushed Stone 4 in. Thick

Ground Slopes Away
From Wall at 5%
(6 in. per 10 ft)
If Exterior Grade is Lower
Than Interior Crawlspace
Grade, No Perimeter
Drain is Necessary

Masonry Foundation Wall
Continuous Polyethylene
Vapor Barrier/Air Barrier
(All Joints Taped) Taped to
Perimeter Rigid Insulation
Capillary Break Over Footing

Concrete Footing
Below Frost Depth

Dampprooﬁng

Further note that the gap created by the wood furring needs to be sealed at the bottom of the cladding.
A plastic mesh wrapped in an insect screen serves this
function.
Figure 9 illustrates a slab-on-grade foundation constructed using a monolithic concrete slab/grade beam.
Note the " turned down " portion of the concrete slab
at the perimeter. This turned down section acts as the
" grade beam. " The monolithic concrete slab/grade beam
is insulated at the perimeter with exterior rigid insulation. Exterior slab edge insulation can act as a pathway
for termite entry. The use of stainless steel termite
shields set in mastic and sealed to the top of the monolithic concrete slab/grade beam addresses this pathway.

FIGURE 8 Slab-on-grade foundation constructed using a masonry stem wall with
a thermally uncoupled concrete slab. In " heavy " termite infestation regions,
borate-treated lumber framing and insulation should be used.
Cavity Insulation
Wood Siding
(All Surfaces Painted)
Gypsum Board
Air Space
Sill Gasket
Sealant, Adhesive or Gasket
Wood Furring
Rigid Insulation
Termite Shield Set in Mastic (Also
(Taped or Sealed Joints)
Serves as Capillary Break)
Sealant, Adhesive or Gasket
Polyethylene Vapor Barrier
Plastic Mesh Wrapped
In Insect Screen
Rodent Protection for
Continuous Rigid Insulation
For Pest Protection Provide
Concrete Slab
2 ft of Pea Gravel or
Crushed Stone 4 in. Thick
Rigid Insulation Extends
Horizontally 2 ft
Protective Membrane
Granular Capillary Break and
(Also Acts as Capillary Break)
Drainage Pad (No Fines)

Ground Slopes Away From Wall
at 5% (6 in. per 10 ft)

Top Course Filled Solid
Rigid Insulation as Bond
Break Material

Dampprooﬁng

Capillary Break Over Footing
Masonry Foundation Wall
Concrete Footing
Below Frost Depth

The joints in the termite shield need to be overlapped
and sealed. The termite shield needs to extend outward
past the exterior edge of the exterior slab edge insulation and its associated protection layer a minimum
of ¾ in. (19 mm) to impede the ability of termites to
bridge the shield. This also facilitates visual inspection
of the effectiveness of the termite shield. Additionally, a
removable strip of insulation and protection board providing an inspection gap is recommended.
Penetrations where plumbing and other services penetrate concrete slabs need to be sealed. The most effective approach is to wrap the service penetration with a
stainless steel mesh " skirt " clamped to the service penetration. The mesh is subsequently cast into the concrete
(Photo 6).
Block pest entries. Seal utility openings and joints
between materials. Use corrosion-resistant materials
such as copper or stainless steel mesh. Rodents can chew
through many materials. Prevent animals and insects
from entering cladding systems. Protect exterior insulation from ground contact. If ground contact cannot be
avoided, use termite shields.
M AY 2021

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