Building Official Determination 25-03: Adding a bathroom

Building Code Guides (BCGs) and Building Official Determinations (BODs) provide answers about the application of building codes and outline optional alternates. BODs are typically smaller in scope and address simpler questions. Code Guides provide a comprehensive alternative to a complicated set of code requirements.

BOD 25-03: Adding a bathroom

Oregon Residential Specialty Code (ORSC)

QUESTION:  All portions of a dwelling are required to have a means of egress that meets the safety standards in R311. The Habitable Spaces Code Guide (BCG 96-12) provides options for existing spaces being converted to habitable space, but the definition of “habitable space” excludes bathrooms and toilet rooms. Can a bathroom be added within a non-habitable basement, attic or garage using the more lenient alternatives in the Habitable Spaces Code Guide? Are any other alternatives allowed for new bathrooms in existing spaces?

RESPONSE:  Yes. Although the Habitable Spaces Code Guide was developed to address conversion to habitable space, the options in the code guide are available for new uses in non-habitable spaces as well. Adding a bathroom on another level increases traffic to that floor level and must meet minimum access and egress safety measures.

1. To provide a means of egress, a three foot wide path must be provided from the new bathroom to the stairway or to an exterior door with at least 6 foot 2 inches clear height and 30 inches clear width. The path may meet the minimum ceiling height requirements in the Habitable Spaces Code Guide instead of the full seven feet required by the ORSC. If the space is owner-occupied, the “Acknowledgement of Exemptions” covenant is an option for areas that do not meet the minimum ceiling heights in the code guide.  

2. The stairway serving the floor level with the new bathroom may meet the reduced dimensional requirements in the Habitable Spaces Code Guide instead of requirements in R311.7. The exemption covenant may not be used to reduce headroom above the stair or landings. Noncompliant stairs must either be reconstructed to meet the minimum dimensional standards or walled off and a compliant means of egress must be provided.

3. If no structural alterations are proposed that affect the floor framing, a bathroom with a shower may be added to an attic without structural assessment of floor loading. If a bathtub is installed, structural calculations must be provided to address the structural adequacy of the floor framing based on applicable design gravity loads.

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