New Homes and Accessory Dwellings

Building Permits are a two-part process with reviews from both Planning & Zoning and Building Safety. Planning & Zoning reviews your project for compliance with zoning regulations, while Building Safety reviews your project for compliance with building codes.

 All structures need to meet required setbacks and height limitations. Setbacks are how far structures need to be from the property lines. These regulations are determined by a property’s zone district.

In this Section:


Accessory Dwelling Units

An Accessory Dwelling Unit (ADU) is a secondary dwelling or accessory home on the property. Often ADUs are called mother-in-law units or granny flats.

We frequently see Building Permits for the following types of Accessory Dwelling Unit (ADU) projects:

  • Basement ADUs
  • ADUs above garages
  • ADUs as detached structures

The County has limitations on how much accessory square footage can be on a property and how large ADUs can be. All regulations related to ADUs and accessory square footage are in the Accessory Uses section of the Jefferson County Zoning Resolution and in our Accessory Square Footage Guide (PDF).

Before applying for a Building Permit for an addition to create an ADU, you will want to ensure that your plans comply with the ADU requirements, accessory square footage requirements, and requirements from your property’s zone district.

ADUs may not be in easements or floodplains. ADUs are treated like new home, meaning staff will review access, water, wastewater, and fire protection and mitigation at the time of permitting an ADU, even if an existing home on the property has already demonstrated those items. Projects that require grading more than a half-acre of land will likely trigger a review of the land disturbance/grading work through a Grading Permit or Notice of Intent. Please see Engineering and Earthwork for more information.

We recommend getting in touch with a Planner about your project and determine exactly which documents will be required as a part of the permitting process, as those do change depending on the scope of the project and property characteristics.

Applications and Documents

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Apartments and Condominiums

New apartment and condominium complexes are required to go through a Site Development Plan process if the zoning allows for the use. Please see the Site Development Plan Process Guide for more information about this process.

All interior renovations and remodels that involve moving, modifying or removing walls or windows require a Building Permit. Renovations involving only cabinet, flooring or counter replacements in the same general locations may not need a permit. Renovations to create a new kitchen, bedrooms or bathrooms require a Planning & Zoning review.

If a renter is to pull a Building Permit, they will need to provide a copy of their lease demonstrating their ability to make improvements.

Applications and Documents

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Attached House

The County has a few types of attached homes:

  • Two-family attached homes are similar to duplexes. There are two units, each designed for occupancy by a single family. Two-family attached homes are on separate lots but share a wall along one property line.
  • Duplexes are detached buildings designed for occupancy by two families living in separate units. The single two-unit structure is located on one lot.
  • Townhomes are single-family attached units constructed in a group of three or more attached units. Each unit has its own lot and is designed for occupancy by no more than one family.
  • A single-family attached home is an umbrella term for two-family attached homes or townhomes.

All new homes (dwelling units) require a Building Permit. For attached homes a Building Permit is required for each individual unit—two Building Permits for two-family dwellings, one for each side.

Dwellings may not be in easements or floodplains. Staff will review access, water, wastewater, and fire protection and mitigation at the time of permitting a new dwelling. New homes in the mountains will need to complete Defensible Space requirements for wildfire safety.

Dwellings are considered primary structures in residential zone districts, which will trigger a review of the land disturbance/grading work through a Grading Permit or Notice of Intent. Please see Engineering and Earthwork for more information. Dwellings in geohazard areas may need to complete soils testing and a geotechnical report as a part of the Building Permit process.

Notes from a subdivision plat, from when the property was subdivided, may require additional documents or processes.

All new driveways or access points to County-maintained roadways or Right-of-Way will require an Access Permit. Please see Driveways and Roadways below for more information.

We recommend getting in touch with a Planner about your project and determine exactly which documents will be required as a part of the permitting process, as those can change depending on the scope of the project and property characteristics.

Applications and Documents

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Driveways and Roadways

  • All new driveways and proposed modifications to existing driveways taking access from a County-maintained roadway require an Access Permit
  • All work and modifications to driveways within 15 feet of public roads or 25 feet for public arterials require an Access Permit
  • Measurements are taken to the edge of pavement or Right-of-Way, whichever is closer.

New driveways or access points to County-maintained roadways, or modifications to existing driveways, require an Access Permit. This is the process by which the County’s Road & Bridge division reviews access-related work to ensure it won’t interfere with drainage or culverts, plow operations or other roadway maintenance issues. This permit also ensures driveways and other access-related work comply with the County’s transportation standards, such as intersection spacing requirements.

Planning & Zoning and Road & Bridge have standards for culverts and driveway spacing which will be reviewed as a part of the Access Permit. Culvert standards can be found in the Building Permits Policy document under the Access Permits section, and driveway spacing standards can be found in the Transportation Design & Construction Manual and on the backside of the Access Permit Application (PDF).

Access Permits are sometimes completed in coordination with permits for land disturbance or grading work. Please see our Engineering and Earthwork page for more information. An Access Permit is required as a part of the Building Permit process for any new home on a County-maintained roadway, see our New Homes and Accessory Dwellings page for more information.

These permits involve having your Road & Bridge District inspect the area before work begins as a condition of being issued a permit, and again once work is completed. Please apply for the permit with Planning & Zoning before calling your district for an inspection.

  • Central and North JeffCo: Road & Bridge District 1 – 303-271-5200
  • South JeffCo: Road & Bridge District 2 – 303-271-5219
  • Evergreen: Road & Bridge District 3 – 303-271-5249
  • Conifer and South Mountains: Road & Bridge District 4 – 303-271-5243

Applications and Documents

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House (single-family detached)

All new homes (dwelling units) require a Building Permit.

Dwellings may not be in easements or floodplains. Staff will review access, water, wastewater, and fire protection and mitigation at the time of permitting a new dwelling. New homes in the mountains will need to complete Defensible Space requirements for wildfire safety.

Dwellings are considered primary structures in residential zone districts, which will trigger a review of the land disturbance/grading work through a Grading Permit or Notice of Intent. Please see Engineering and Earthwork for more information. Dwellings in geohazard areas may need to complete soils testing and a geotechnical report as a part of the Building Permit process.

Notes from a subdivision plat, from when the property was subdivided, may require additional documents or processes.

All new driveways or access points to County-maintained roadways or Right-of-Way will require an Access Permit. Please see Driveways and Roadways above for more information.

We recommend getting in touch with a Planner about your project and determine exactly which documents will be required as a part of the permitting process, as those do change depending on the scope of the project and property characteristics.

Applications and Documents

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