Based on the 2021 Boulder County Building Code (BCBCA), 2021 International Residential Code (IRC) and the Current version of the National Electrical Code (NEC) adopted by the Colorado State Electrical Board. Boulder County Building Code Amendments
Boulder County Planning Publications
Basement Finishing B03
Building Permit submittal requirements
All construction drawings must be submitted in PDF format at the time of your online building permit application Boulder County Permit Records & Online Application Submittals.
Energy Conservation Requirements
See 2021 Boulder County BuildSmart Guide for Energy Conservation Requirements.
Plan Requirements
Providing the following details to your basement finish plans allows the plan review process to proceed smoothly and avoids unnecessary delays. Minimum 1/4″ = 1 sq. ft. scaled plans.
Provide a Floor Plan that Contains the Following Details:
- The overall dimensions.
- Dimensions of each individual space.
- Label the use of each space.
- Show the window and door size (height and width), location, and style.
- Provide the location and dimensions of egress window well(s).
- Note the location of each plumbing fixture, mechanical appliance, and electrical panel.
- Show foundation walls.
Provide a Wall Section Detail, or Note the Following on the Plan:
- The wall insulation type and R-value must be per HERS rating or Prescriptive Path.
- The furred wall stud size and spacing.
- The partition wall stud size and spacing.
- The interior wall and ceiling finish materials.
- The height of the egress window well(s) and the dimension from the finished floor to the egress windowsill(s).
Design Considerations
Framing, Insulation, and Sheetrock Requirements
- Floating slab techniques (1, 2, or 3 inch) are recommended, especially in the plain’s areas of the county.
- Partitions framed on concrete slabs require a treated wood bottom plate. (IRC R317)
- Fire blocking is required at the top plate of and at all dropped ceilings and horizontally every 10 feet (IRC R302.11)
- Enclosed space under stairs that is accessed by a door or access panel shall have walls, under-stair surface and any soffits protected on the enclosed side with ½ inch gypsum board. (IRC R302.7)
- Ceiling heights for habitable rooms shall be a minimum of 7 feet in height measured from the finished floor to the lowest projection of the ceiling. (IRC R305.1)
Mechanical Requirements
- Appliances shall be accessible for inspection, service, repair and replacement without removing permanent construction. 30-inches of working depth and width shall be provided in front of the control side of an appliance. (IRC M1305.1)
- Appliances and equipment shall be installed in accordance with the conditions of their listing. Manufacturer’s installation instructions must be available at the time of the inspection. (IRC G2408.1, M1307.1, and M1401.1)
- Combustion air is required for all liquid fuel, solid fuel and gas appliances. (IRC M1701.1, G2407)
- Gas burning appliances may not be located in or obtain combustion air from: a sleeping room, bathroom, toilet room, or storage closet unless it is a direct vent appliance or installed in an enclosure that opens only into a bedroom or bathroom in and such enclosure is provided with a solid weather-stripped door, a self-closing device and all combustion air is taken from the outdoors. (IRC G2406.2)
- Bathrooms exhaust fans shall exhaust directly to the exterior and must be provided in bathrooms where windows of at least 3 square feet (one-half of which must be openable) are not installed.
- If mechanical ventilation is used it must be capable of providing an exhaust capacity of 50 cfm intermittent or 20 cfm continuous exhaust (IRC R303.3 & Table M1505.4.4)
Electrical
- At least one wall switch-controlled lighting outlet shall be installed in every habitable room, stairways, hallways, utility rooms and basements containing equipment or used for storage. (NEC 210.70)
- Tamper-resistant receptacle outlets are required in every bedroom, living room, recreation room or similar areas, spaced such that no point measured horizontally along the wall is more that 6 feet from a receptacle. (NEC 210.52, 406.3, 406.12)
- Ground fault protection shall be provided on all 125-volt through 250-volt single phase 15 and 20-ampere receptacle outlets installed in bathrooms, basements, and within 6’ of sinks, and laundry areas. Ground-fault circuit interrupters shall be installed in readily accessible locations. (NEC 210.8, 210.8(D)
- At least one 20-amp branch circuit shall supply bathroom receptacles and at least one 20-amp branch circuit shall supply laundry rooms. (NEC 210.52(B)
- A combination type arc-fault circuit interrupters must be installed on all 120-volt 15 and 20-amp branch circuits installed in family rooms, living rooms, libraries, dens, bedrooms, recreation rooms, closets, hallways, laundry areas and similar rooms or areas. Arc-fault circuit interrupters shall be installed in readily accessible locations. (NEC 210.12)
Smoke and Carbon Alarm Requirements are required see B76 Smoke Alarms and Carbon Monoxide Alarms
Fire Sprinkler Requirements
- Dwellings which have an existing automatic fire sprinkler system must have the system retrofitted to conform with the layout of the finished basement. Consult your Fire District about sprinkler plan requirements and sprinkler inspections.
Egress Requirements
- Each sleeping room must be provided with an approved emergency escape and rescue opening window or door. If the bottom of the emergency escape and rescue opening is below the adjacent grade, an area well is required. (R310) see Boulder County Emergency Escape & Rescue Openings Webpage for more information.
- IRC R310.7 Alterations or repairs of existing basements. New sleeping rooms created in an existing basement shall be provided with emergency escape and rescue openings in accordance with Section R310.1. Other than new sleeping rooms, where existing basements undergo alterations or repairs, an emergency escape and rescue opening is not required.
Light and Ventilation Requirements
- Habitable rooms shall have an aggrege glazing area (natural light) a minimum of 8% of the floor area or provide artificial light producing an average of 6 footcandles over the area of the room at a height of 30 inches above the floor level and comply with the ventilation requirement. (R303.1)
- Each habitable space shall be provided with natural ventilation equal to 4% of the floor area or provide an approved mechanical ventilation system in that room capable of producing 0.35 air changes per hour (R303.1) or a whole-house mechanical ventilation system capable of supplying outdoor ventilation air sufficient to meet table N1103.6.2 (BCBCA).
- Habitable rooms shall have heating facilities capable of maintaining 68° at 3 feet above the floor and 2 feet from exterior walls. (IRC R303.10)
Per the 2021 IBC, 2021 IRC, and Boulder County Building Code Amendments.
No person shall erect, construct, reconstruct, alter, demolish, deconstruct, or change the use of any building or other structure without first obtaining a building permit.
Work Exempt from a Building Permit
Exemptions from permit requirements of this code shall not be deemed to grant authorization for any work to be done in any manner in violation of the provisions of this code or any other laws or ordinances of this jurisdiction. Permits shall not be required for the following:
Building
One-story detached accessory structures, other than storm shelters, used as a storage shed, playhouse for private use, greenhouse, chicken coop, agricultural loafing shed, or similar uses, provided that:
the floor area of any structure does not exceed 120 square feet (11 m2), except agricultural loafing sheds, which may not exceed 200 square feet.
the structure height does not exceed 12 feet,
the structure does not have any utilities, and
the structure does not violate the conditions of any existing land use approval or conservation easement.
The number of allowed detached accessory structures which may be constructed without a building permit shall be determined by the size of the subject parcel:
One detached accessory structure may be constructed without a building permit on parcels 0.5 acres or less in size.
Two detached accessory structures may be constructed without a building permit on parcels greater than 0.5 acre and less than ten acres.
Three detached accessory structures may be constructed without a building permit on parcels 10 acres and larger.
Fences not over 6 feet (2134 mm) high.
Retaining walls that are not over 4 feet (1219 mm) in height measured from the bottom of the footing to the top of the wall, unless supporting a surcharge or impounding Class I, II or IIIA liquids.
Water tanks supported directly on grade if the capacity is not greater than 5,000 gallons (18 925 L) and the ratio of height to diameter or width is not greater than 2:1.
Sidewalks and driveways not more than 30 inches (762 mm) above adjacent grade, and not over any basement or story below and are not part of an accessible route and not subject to a grading permit.
Painting, papering, tiling, carpeting, cabinets, counter tops and similar finish work, in one- and two-family dwellings and their accessory structures.
Exception:
Cabinets and countertops with plumbing or electrical as part of remodels in one- and two-family dwellings and their accessory structures are required to have a building permit.
Temporary motion picture, television and theater stage sets and scenery.
Prefabricated swimming pools where the pool walls are entirely above the adjacent grade and the capacity does not exceed 5,000 gallons accessory to a Group R-3 occupancy and one- and two-family dwellings and their accessory structures as regulated by the International Residential Code that are less than 24 inches (610 mm) deep, are not greater than 5,000 gallons (18 925 L) and are installed entirely above ground.
Shade cloth structures constructed for nursery or agricultural purposes, not including service systems.
Swings and other playground equipment accessory to detached one- and two-family dwellings.
Window awnings in one- and two-family dwellings and their accessory structures as regulated by the International Residential Code, Group R-3, and U occupancies, supported by an exterior wall that which do not project more than 54 inches (1372 mm) from the exterior wall and do not require additional support.
Nonfixed and movable fixtures, cases, racks, counters and partitions not over 5 feet 9 inches (1753 mm) in height.
Antennas and/or their supporting structures other than buildings, accessory to residential use less than ten feet in height and lower than the structure height limit in the zoning district in which located, or which were constructed or erected prior to July 1, 1988.
Temporary emergency noncommercial telecommunication-sites operated by a governmental agency, or by a volunteer public safety agency officially sanctioned by a governmental agency for that purpose, for public safety communication uses, for a period not to exceed six months.
Residential decks for one- and two-family dwellings and their accessory structures as regulated by the International Residential Code, not exceeding 200 square feet (18.58 m2 ) in area, that are not more than 30 inches (762 mm) above grade at any point, are not attached to a dwelling and do not serve the exit door required by Section R311.4.
Roof covering repair, shingle repair or replacement, not exceeding one square (100 square feet of area) (9.29 m2) of covering per building or structure.
Electrical
Repairs and maintenance: Minor repair work, including the replacement of lamps or the connection of approved portable electrical equipment to approved permanently installed receptacles.
Radio and television transmitting stations: The provisions of this code shall not apply to electrical equipment used for radio and television transmissions but do apply to equipment and wiring for a power supply and the 10 installations of towers and antennas.
Temporary testing systems: A permit shall not be required for the installation of any temporary system required for the testing or servicing of electrical equipment or apparatus.
Gas
Portable heating appliances.
Replacement of any minor part that approval of equipment or make such equipment unsafe.
Mechanical
Portable heating appliances.
Portable ventilation appliances and equipment.
Portable cooling unit.
Steam, hot or chilled water piping within any heating or cooling equipment regulated by this code.
Replacement of any part that does not alter approval of equipment or make such equipment unsafe.
Portable evaporative cooler.
Self-contained refrigeration system containing 10 pounds (4.54 kg) or less of refrigerant or that are actuated by motors of 1 horsepower (746 W) or less.
Portable-fuel-cell appliances that are not connected to a fixed piping system and are not interconnected to a power grid, in one- and two-family dwellings and their accessory structures.
Plumbing
The stopping of leaks in drains, water, soil, waste or vent pipe, provided, however, that if any concealed trap, drain pipe, water, soil, waste, or vent pipe becomes defective and it becomes necessary to remove and replace the same with new material, such work shall be considered as new work and a permit shall be obtained and inspection made as provided in this code.
The clearing of stoppages or the repairing of leaks in pipes, valves or fixtures and the removal and reinstallation of water closets, provided that such repairs do not involve or require the replacement or rearrangement of valves, pipes or fixtures.
105.2.1 Emergency repairs.
Where equipment replacements and repairs must be performed in an emergency situation, the permit application shall be submitted within the next working business day to the building official.
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