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home city services Planning and Development Services Development Review Two Dwelling Units on a property

Adding a second dwelling unit#

If you are considering adding a second dwelling unit to your property, there may be options available to you. Different options are available in different zone districts. 

Each zone district has its own set of rules about what land can be used for, the sizes of lots, how buildings can be designed and more. 

See a zoning map

New dwelling units are not allowed in the Poudre River 100-year floodplain. Please check if your property is in this floodplain. 

Floodplain map

Ways to add a second dwelling unit#

Accessory Dwelling Unit#

An Accessory Dwelling Unit (ADU) is a small house or unit that is on the same property as a larger building. 

An ADU: 

  • Contains everything someone needs to live in a home: a kitchen, bathroom and living area.
  • Is on the same property or lot as another primary dwelling unit.
  • Can be attached to a house or detached.

Accessory Dwelling Units may be permitted on many lots in Fort Collins. They may be permitted on a lot with a detached house, duplex or triplex.

It will not be possible to fit an ADU on all of the properties that meet the above descriptions due to standards that regulate setbacks, utility access, fire access, stormwater mitigation, and possibly others. 

More resources on ADUs#

Drawing of a house on a lot with a smaller house behind it it the rear yard.

If you are considering building an ADU on your property, please visit our ADU resource page to learn more. 

Exploring Your Idea: Accessory Dwelling Unit

A Second Detached House#

A Second Detached House

In some zone districts, two or more detached houses may be permitted on a lot. Some of these zone districts have density limits that may restrict the number of houses on a lot. 

  • Rural Lands District (RUL)
  • Residential Foothills District (RF)
  • Community Commercial District (CC)
  • Community Commercial - North College District (CCN)
  • Community Commercial - Poudre River District (CCR)
  • General commercial District (CG)
  • Service Commercial District (CS)
  • Limited Commercial District (CL)
  • Low Density Mixed-Use Neighborhood District (LMN)
  • Medium Density Mixed-Use Neighborhood District (MMN)
  • High Density Mixed-Use Neighborhood District (HMN)
  • Neighborhood Commercial District (NC)
  • Downtown District (D)
  • Harmony Corridor District (HC)
  • Employment District (E)
  • Industrial District (I)
  • River Conservation District (RC)

It will not be possible to fit a second dwelling unit on all of the properties in the above zone districts due to standards that regulate setbacks, on-site (off-street) parking, utility access, fire access, stormwater mitigation, and possibly others.

Please see the Land Use Code for more detailed regulations. 

See a zoning map

Duplex#

Drawing of a duplex on a lot next to a house.

A duplex is a building with two residential units, either side-by-side, stacked, or with a second unit over an attached garage. These buildings are typically 1 or 2 stories and are designed to look like a medium or large detached house to fit in well with single-unit neighborhoods.

Duplex units may both be owned by the same entity and one or both units are rented out. This is called a two-unit dwelling. 

Duplex units may be owned separately in one of two ways:
- Condominium: this is where each party owns the air space of the individual unit, but the land under the unit is co-owned. The individual units may be occupied by their owners or by renters.
- Single-unit attached: this is where the property, including the land under the building, is subdivided into two parcels. The individual units may be occupied by their owners or by renters. 

Duplexes are permitted in the following zone districts:

  • Urban Estates (UE) Zone District, 
  • Low Density Mixed-Use (LMN) Zone District 
  • Medium Density Mixed-Use (MMN) Zone District 
  • Old Town Medium Density (OT-B) Zone District 
  • Old Town High Density (OT-C) Zone District
  • Community Commercial (CC) Zone District
  • Community Commercial - North College (CCN) Zone District
  • Community Commercial - Poudre River District (CCR) Zone District
  • General Commercial (CG) Zone District 
  • Service Commercial (CS) Zone District
  • Limited Commercial (CL) Zone District, including:
    • Riverside Area
    • All other areas
  • Neighborhood Commercial (NC) Zone District
  • Harmony Corridor (HC) Zone District
  • Employment (E) Zone District

  • Rural Lands District (RUL) - only in a Residential Cluster
  • Residential Foothills District (RF) - only in a Residential Cluster

It will not be possible to fit a duplex on all of the properties in the above zone districts due to standards that regulate setbacks, on-site (off-street) parking, utility access, fire access, stormwater mitigation, and possibly others. 

Please see the Land Use Code for more detailed regulations. 

See a zoning map

Two-unit rowhouse#

Drawing of a series of attached rowhouses

A rowhouse consists of residential units that are side-by-side and share walls. Rowhouses are typically narrow, with each home having its own entrance that faces the street.  

Rowhouse units may both be owned by the same entity and one or both units are rented out. This is called a two-unit dwelling.

Rowhouse units may be owned separately in one of two ways:
- Condominium: this is where each party owns the air space of the individual unit, but the land under the unit is co-owned. The individual units may be occupied by their owners or by renters.
- Single-unit attached: this is where the property, including the land under the building, is subdivided into two parcels. The individual units may be occupied by their owners or by renters.

Rowhouses are permitted in the following zone districts:

  • Low Density Mixed-Use (LMN) District 
  • Medium Density Mixed-Use (MMN) District
  • Old Town Medium Density District (OT-B)
  • Old Town Medium Density District (OT-B)
  • Old Town High Density District (OT-C)
  • Downtown (D) District, including:
    • Canyon Ave./Civic/North Mason subdistrict
    • Innovation/River subdistrict
    • Campus North subdistrict
    • Entryway Corridor subdistrict
  • Community Commercial (CC) District
  • Community Commercial - North College (CCN) District
  • Community Commercial- Poudre River (CCR) District
  • General Commercial (CG) District
  • Service Commercial (CS) District
  • Neighborhood Commercial (NC) District
  • Limited Commercial (CL) District, including:
    • Riverside Area
    • All other areas
  • Harmony Corridor (HC) District
  • Employment (E) District

Single unit attached dwellings are permitted in the following residential zone districts:

  • Rural Lands District (RUL) - only in a residential cluster
  • Urban Estates District (UE) - 
  • Residential Foothills District (RF)

It will not be possible to fit a single unit attached dwelling on all of the properties in the above zone districts due to standards that regulate setbacks, on-site (off-street) parking, utility access, fire access, stormwater mitigation, and possibly others. 

Please see the Land Use Code for more detailed regulations. 

See a zoning map

Subdividing a Property#

In some cases it may be possible to add a second dwelling unit by subdividing a property and putting the second unit on the newly-created parcel. This may be possible on properties in the RUL, RF, and RL Zone Districts, that only allow one dwelling unit on a property.

Residential zone districts have minimum lot sizes and minimum lot widths that will preclude this option in most cases. Please see our page on subdividing properties for more information. 

Learn about subdividing

Zone District Minimum lot area Minimum lot width
Rural Lands District (RUL) 10 acres 200 feet
Urban Estates District (UE) 1/2 acre 100 feet, OR
60 feet if the subdivision was developed prior to March 28, 1997
Residential Foothills (RF) 100,000 square feet (2.29 acres) 200 feet
Residential Low Density (RL)

6,000 square feet, OR
3 times the total floor area of the buildings, whichever is larger

60 feet
Old Town Low Density (OT-A) 6,000 square feet 40 feet
Old Town Medium Density (OT-B) 5,000 square feet for a detached house or duplex.
6,000 square feet for all other uses 		40 feet for a detached house or duplex.
50 feet for all other uses.
Old Town High Density (OT-C) None 40 feet for a single-family house or duplex.
50 feet for all other uses.
Low Density Mixed-Use Neighborhood (LMN) None,
But only up to 1 dwelling unit per 4,840 square feet  		None
Medium Density Mixed-Use Neighborhood (MMN) None None
Downtown (D) None None

Please see the Land Use Code for more detailed regulations. 

Ready to get started#

The City offers free Conceptual Design Review meetings where you can submit an idea or proposal about adding a second dwelling unit and receive feedback and fee estimates and process information.

This is would be done prior to formally submitting an application. 

Apply for a Conceptual Design Review meeting

Additional Information#