C402.5.1
Air
barriers. A continuous air barrier shall be provided throughout the
building thermal envelope. The continuous air barriers shall be located on the
inside or outside of the
building thermal envelope, located
within the assemblies composing the
building thermal envelope,
or any combination thereof. The air barrier shall comply with Sections
C402.5.1.1 and C402.5.1.2.
C402.5.1.1
Air barrier construction. The
continuous air barrier
shall be constructed to comply with the following:
1. The air barrier shall be continuous for
all assemblies that are the thermal envelope of the building and across the
joints and assemblies.
2. Air
barrier joints and seams shall be sealed, including sealing transitions in
places and changes in materials. The joints and seals shall be securely
installed in or on the joint for its entire length so as not to dislodge,
loosen or otherwise impair its ability to resist positive and negative pressure
from wind, stack effect and mechanical ventilation.
3. Penetrations of the air barrier shall be
caulked, gasketed or otherwise sealed in a manner compatible with the
construction materials and location. Sealing shall allow for expansion,
contraction and mechanical vibration. Joints and seams associated with
penetrations shall be sealed in the same manner or taped. Sealing materials
shall be securely installed around the penetration so as not to dislodge,
loosen or otherwise impair the penetrations' ability to resist positive and
negative pressure from wind, stack effect, and mechanical ventilation. Sealing
of concealed fire sprinklers, where required, shall be in a manner that is
recommended by the manufacturer. Caulking or other adhesive sealants shall not
be used to fill voids between fire sprinkler cover plates and walls or
ceilings.
4. Recessed lighting
fixtures shall comply with Section C402.5.8. Where similar objects are
installed which penetrate the air barrier, provisions shall be made to maintain
the integrity of the air barrier.
5. Construction documents shall contain a
diagram showing the building's pressure boundary in plan(s) and section(s) and
a calculation of the area of the pressure boundary to be considered in the
test.
C402.5.1.2
Air barrier compliance. A continuous air barrier for the opaque
building envelope shall comply with the following:
1. Group R dwelling units that are accessed
directly from the outdoors shall meet the provisions of Section
C402.5.2.
2. All other buildings or
portions of buildings shall meet the provisions of Section C402.5.3.
C402.5.2
Enclosure
testing for dwelling and sleeping unit accessed directly from the
outdoors. For dwelling units accessed directly from outdoors, the
building thermal envelope shall be tested in accordance with
ASTM E779, ANSI/RESNET/ICC 380, ASTM E1827 or an equivalent method approved by
the
code official. The measured air leakage shall not exceed
0.25 cfm/ft
2 (1.27 L/s
m
2) of the
testing unit enclosure
area multiple dwelling units or sleeping units or other occupiable
conditioned spaces are contained within one
building thermal
envelope and are accessed directly from the outdoors, each unit shall
be considered an individual testing unit, and the building air leakage shall be
the weighted average of all testing unit results, weighted by each testing
unit's enclosure area. Units shall be tested separately with an unguarded
blower door test as follows:
1. Where
buildings have fewer than eight testing units, each testing unit shall be
tested.
2. For buildings with eight
or more testing units, the greater of seven units or 20 percent of the testing
units in the building shall be tested, including a top floor unit, a ground
floor unit and a unit with the largest testing unit enclosure
area. For each tested unit that exceeds the maximum air leakage rate,
an additional two units shall be tested, including a mixture of testing unit
types and locations.
3. Test shall
be accomplished using either a) both pressurization and depressurization or b)
pressurization alone, but not depressurization alone. The test results shall be
plotted against the correct P for pressurization in accordance with Section 9.4
of ASTM E779.
Where the measured air leakage rate exceeds 0.25
cfm/ft2 (2.0 L/s x m2)
corrective action shall be taken to seal leaks in the air barrier
Post-corrective action testing and repeated corrective action measures will be
taken until the required air leakage rating is achieved. Final passing air
leakage test results shall be submitted to the code
official.
C402.5.3
Building thermal envelope
testing. The
building thermal envelope shall be tested
in accordance with ASTM E779, ANSI/RESNET/ICC 380, ASTM E3158 or ASTM E1827 or
an equivalent method approved by the code official. The measured air leakage
shall not exceed 0.25 cfm/ft
2 (1.27 L/s ×
m
2) of the
building thermal envelope
area at a pressure differential of 0.3 inch water gauge (75 Pa).
Alternatively, portions of the building shall be tested and the measured air
leakages shall be area weighted by the surface areas of the building envelope
in each portion. The weighted average test results shall not exceed the whole
building leakage limit. In the alternative approach, the following portions of
the building shall be tested:
1. The entire
envelope area of all stories that have any spaces directly under a
roof.
2. The entire envelope area
of all stories that have a building entrance, exposed floor, or loading dock,
or are below grade.
3.
Representative above-grade sections of the building totaling at least 25
percent of the wall area enclosing the remaining conditioned space.
4. Test shall be accomplished using either a)
both pressurization and depressurization or b) pressurization alone, but not
depressurization alone. The test results shall be plotted against the correct P
for pressurization in accordance with Section 9.4 of ASTM E779.
Where the measured air leakage rate exceeds 0.25
cfm/ft2 (2.0 L/s x m2)
corrective action shall be taken to seal leaks in the air barrier.
Post-corrective action testing and repeated corrective action measures will be
taken until the required air leakage rating is achieved. Final passing of the
air leakage test results shall be submitted to the code
official.
C402.5.4
Building test for mixed-use
buildings. Where a building is three or fewer stories above grade plane
and contains both commercial and residential uses, the air barrier of the R-2
and R-3 occupancy areas of the building is permitted to be separately tested
according to Section R402.4.1.2. Alternatively, it is permissible to test the
air barrier of the entire building according to Section C402.5.3, provided that
the tested air leakage rate does not exceed the rate specified in Section
C402.5.3.
Notes
Wash. Admin. Code §
51-11C-40241
Amended by
WSR
16-03-072, Filed 1/19/2016, effective
7/1/2016
Amended by
WSR
19-24-040, Filed 11/26/2019, effective
7/1/2020
Amended by
WSR
22-14-091, Filed 7/1/2022, effective
7/1/2023
Statutory Authority:
RCW
19.27A.020,
19.27A.025 and
chapters
19.27 and
34.05 RCW. 13-04-056, §
51-11C-40241, filed 2/1/13, effective
7/1/13.