PDFWAC 51-51-60104

Appendix AQTiny houses.

AQ102 Definitions.
LOFT. See Chapter 2.
TINY HOUSE. A dwelling unit that is 400 square feet (37 m2) or less in floor area excluding sleeping lofts.
AQ103.1 Minimum ceiling height. Habitable space in tiny houses shall have a ceiling height of not less than 6 feet 8 inches (2032 mm). Bathrooms, toilet rooms and kitchens shall have a ceiling height of not less than 6 feet 4 inches (1930 mm). Obstructions including, but not limited to, beams, girders, ducts and lighting, shall not extend below these minimum ceiling heights.
Ceiling heights in lofts shall be in accordance with Section R333.
AQ104 Energy conservation.
AQ104.1 Air leakage testing. The air leakage rate for tiny houses shall not exceed 0.30 cfm at 50 Pascals of pressure per square foot of the dwelling unit enclosure area. Testing shall be conducted in accordance with RESNET/ICC 380, ASTM E 779 or ASTM E 1827 and reported at a pressure of 0.2 inch w.g. (50 Pascals). Where required by the code official, testing shall be conducted by an approved third party. A written report of the results of the test shall be signed by the party conducting the test and provided to the code official. Testing shall be performed after the continuous air barrier, including all penetrations, is completed and sealed.
During testing:
1. Exterior windows and doors, fireplace and stove doors shall be closed, but not sealed, beyond the intended weather stripping or other infiltration control measures.
2. Dampers including exhaust, intake, makeup air, backdraft and flue dampers shall be closed, but not sealed beyond intended infiltration control measures.
3. Interior doors, if installed at the time of the test, shall be open.
4. Exterior louvers for continuous ventilation systems and heat recovery ventilators shall be closed and sealed.
5. Heating and cooling systems, if installed at the time of the test, shall be turned off.
6. Supply and return registers, if installed at the time of the test, shall be fully open.
AQ104.1.1 Whole-house mechanical ventilation. Where an air leakage rate not exceeding 0.30 cfm per ft of the dwelling unit enclosure area in accordance with Section AQ106.1 is provided, the tiny house shall be provided with whole-house mechanical ventilation in accordance with Section M1505.4.
AQ105 Emergency escape and rescue openings. This section is not adopted.
AQ106 Energy conservation. This section is not adopted.
[Statutory Authority: RCW 19.27.031 and 19.27.074. WSR 23-23-104, § 51-51-60104, filed 11/15/23, effective 3/16/24; WSR 20-21-041, § 51-51-60104, filed 10/13/20, effective 11/13/20; WSR 20-03-023, § 51-51-60104, filed 1/6/20, effective 7/1/20.]