June 15, 2021 City of Bellevue | Development Services 3
Building Code Requirements for Mechanical Installations
When is a separate building permit required?
Many mechanical HVAC installations involve the need to make structural improvements to the
building or structure where new HVAC equipment will be installed. A separate building permit is
typically needed for structural improvements to allow for review and inspection of those
improvements. Some examples of typical structural improvements done as part of an HVAC
• Modifications to an existing roof or elevated floor to carry the weight of new equipment.
• Installation of screening as required by the Land Use ordinance.
• Connection of wall-mounted installations to an existing building.
Building plans and structural calculations are required in most cases to justify existing and/or new
construction related to gravity or lateral support of new HVAC equipment. If structural calculations
are required by the City of Bellevue, the calculations, details and drawings must be stamped and
signed by an engineer licensed in the state of Washington. Review Table A (attached) to determine
when lateral engineering is required for your project.
Structural improvements not listed here require a separate building permit. If a separate building
permit has already been submitted for review or has been issued, it is not necessary to provide
the same information with the mechanical permit application. New HVAC equipment should not
be installed on elevated roofs or decks until necessary structural improvements have been
completed and approved by the building inspector.
If screening for exterior equipment is required per the Land Use ordinance, provide lateral and
gravity calculations for review. For projects requiring installation of shafts, plans and details
showing the location and support of vertical and/or horizontal shafts must be provided. In many
cases, shafts must be fire resistance-rated; assembly listing numbers and assembly details must
be provided for review.
The installation of a walk-in cooler or walk-in freezer that is custom built, built on site or installed
outside the building perimeter will require a separate building permit. If the unit is installed on
anything other than a slab-on-grade, structural information is required to verify that the floor
system is sufficient.