Page 951 - 2018_IRC

APPENDIX R

Rain-exposed clay plasters shall be finished with a lime-
based or silicate-mineral coating.
AR103.5.3 Separation of wood and plaster. Where
wood framing occurs in light straw-clay walls, such wood
surfaces shall be separated from exterior plaster with
No.15 asphalt felt, Grade D paper or other approved mate-
rial except where the wood is preservative treated or natu-
rally durable.
Exception: Exterior clay plasters shall not be required
to be separated from wood.
AR103.5.4 Bridging across dissimilar substrates.
Bridging shall be installed across dissimilar substrates
prior to the application of plaster. Acceptable bridging
materials include: expanded metal lath, woven wire mesh,
welded wire mesh, fiberglass mesh, reed matting or bur-
lap. Bridging shall extend not less than 4 inches (102 mm),
on both sides of the juncture.
AR103.5.5 Exterior cladding. Exterior cladding shall be
spaced not less than / inch (19.1 mm) from the light
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straw-clay such that a ventilation space is created to allow
for moisture diffusion. Furring strips that create this venti-
lation space shall be securely fastened to the stabilization
members or framing. The cladding shall be fastened to the
wood furring strips in accordance with the manufacturer’s
instructions. Insect screening shall be provided at the top
and bottom of the ventilation space.

SECTION AR104
THERMAL PERFORMANCE
AR104.1 Thermal characteristics. Walls with light straw-
clay infill of densities of greater than or equal to 20 pounds
per cubic foot (480.6 kg/m ) shall be classified as mass walls
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in accordance with Section N1102.2.5 (R402.2.5) and shall
meet the R-value requirements for mass walls in Table
N1102.1.2 (R402.1.2). Walls with light straw-clay infill of
densities less than 20 pounds per cubic foot (480.6 kg/m )
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shall meet the R-value requirements for wood frame walls in
Table N1102.1.2 (R402.1.2).
AR104.2 Thermal resistance. Light straw-clay shall be
deemed to have a thermal resistance as specified in Table
AR103.2.3.

926 2018 INTERNATIONAL RESIDENTIAL CODE ®
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