Residential Build-Out

A build-out analysis attempts to answer how much development has occurred in a community and how much development remains to be built. The Summary of Residential Build-Out Analysis of Properties in Summit County, Colorado (pdf) provides this information for Summit County, assuming continued growth subject to the zoning ordinances and subdivision regulations in place at the time of analysis.

Analysis Components

The build-out analysis is broken out by planning basin, and includes build-out numbers for both the unincorporated areas and incorporated towns in Summit County. (View a locator map (pdf) depicting the four planning basins and six incorporated towns within the county.)

Build-out for the unincorporated portions of the county, and the Towns of Blue River and Montezuma has been calculated by the Summit County Planning Department. Build-out for the remaining four towns in the county (Breckenridge, Dillon, Frisco, and Silverthorne) was obtained from the respective town planning departments.
The Summit County Planning Department works to update build-out numbers for respective planning basins, and adds newly constructed residential units semi-annually (using certificates of occupancy issued by the County Building Department). Build-out numbers are available by basin, subdivision and parcel.

Commercial build-out for the county has not been included in this analysis. The Summit County Planning Department is in the process of completing a detailed commercial build-out analysis. At this time, it is estimated that commercial build-out in unincorporated portions of Summit County is approximately 62%.

The residential build-out analysis is broken out into two categories: absolute build-out and realistic build-out.

Absolute Build-Out

Absolute build-out represents an evaluation of the existing zoning on every parcel of private land in unincorporated portions of the county and determines the maximum potential residential development allowed by that zoning. By subtracting the number of existing units built, we determine an approximation of what remains to be built. This is referred to as absolute build-out, because it represents the absolute or ultimate build-out potential that is permitted by existing zoning.

Absolute build-out is not necessarily a fixed or static number. Some factors that could potentially act to increase absolute build-out in the county include future land trades with the U.S. Forest Service; potential annexations and upzonings by towns of lands that are currently unincorporated; and the creation of new density for future affordable or workforce housing developments.

Policies in the Countywide Comprehensive Plan for Summit County, Colorado limit or cap the creation of new density on unincorporated lands as a means of controlling absolute build-out. However, to date only two of the six municipalities in the county (towns of Blue River and Breckenridge) have embraced this limit on new density. Policies in the Countywide Comprehensive Plan urge cooperative planning with the other towns to encourage them to adopt similar policies controlling the creation of new density. The County continues to work with the towns of Silverthorne, Dillon and Frisco to establish joint planning agreements addressing coordinated land use planning, density and transferable development rights (TDRs).

Realistic Build-Out

Realistic build-out represents a more likely picture of the build-out that may occur in Summit County. It is unlikely absolute build-out, as described above, will be realized or achieved (i.e., the total number of units allowed per zoning will not likely be built). Realistic build-out factors in constraints that could preclude realization of the full development potential allowed under the existing zoning regulations. The factors that need to be considered and contribute to this assumption include, but are not limited to the following:

• On-site and off-site constraints to remaining development (e.g., backcountry parcels that are not readily accessible, parcels that are constrained by wetlands and steep slopes or lack water rights)
• Private property owners electing not to develop their property to its full potential or electing to keep large tracts of land intact because of a desire to maintain a large undisturbed land area
• Development of some properties may be restricted by conservation easements in the future (existing conservation easements have been deducted from the current numbers in the attached analysis)
• Private properties acquired for open space preservation (e.g., open space tax dollars or voter approved funding mechanisms to purchase properties to protect open space).

Summary of Summit County Residential Build-Out

View the Summary of Residential Build-Out Analysis of Properties in Summit County, Colorado (pdf).

 As shown in the build-out analysis, overall, as of December 31, 2015, approximately 29,917 units of the 42,770 units allowed per zoning have been built in the county. This represents an absolute residential build-out of 69.95% (including both the unincorporated areas and the incorporated towns). Summit County Planning Staff estimates that the realistic build-out for the county is approximately 38,845 units, which means that realistic build-out is approximately 77.02% (including both the unincorporated areas and the incorporated towns).

Observations and Additional Information

A number of observations can be made from the residential build-out analysis.

The data indicate that the incorporated towns are more built-out than the unincorporated portions of the county. Among the incorporated towns, the Town of Frisco is the most built-out at approximately 95%, followed by the towns of Blue River and Breckenridge, which are respectively approximately 77% and 80% built out. When looking at the respective planning basins (including both unincorporated areas and incorporated towns), in the context of absolute build-out, the Tenmile Basin is the most built-out of the four basins, with an absolute build-out of approximately 85%, followed by the Snake River and Upper Blue Basins, which are approximately 72% built-out. In terms of realistic build-out, all basins are roughly 70-85% built-out.

The data also show that there are significantly more residential units built in the Upper Blue Basin than any other basin (including both unincorporated areas and incorporated towns). There are approximately 11,300 units built in the Upper Blue Basin, which is more than twice the number of units built in the Lower Blue or Tenmile basins, and over 3,500 units more than exist in the Snake River Basin. The Upper Blue Basin has the most remaining development potential among the four basins, with an absolute build-out potential of approximately 15,800 residential units (nearly 40% of the units permitted within the entire county).

There are approximately 15,600 units built in unincorporated portions of the county, of which approximately 9,000 (60%) are multifamily units. The county build-out analysis indicates there are approximately 6,300 units remaining to be built on unincorporated lands, of which approximately 2,700 units (42%) have the potential to be multifamily. Therefore, nearly half of the remaining units to be built in unincorporated portions of the county are permitted for multifamily.

An analysis of growth rates over the past six years (2010-2015) reveals that there has been an average of 202 new residential housing units built in the county each year. At the same rate of growth, there would be approximately 30,928 residential units in the county by the year 2020, 31,939 units by 2025, and 32,950 units by 2030. These represent respective absolute build out percentages of 73% in 2020, 75% in 2025, and 77% in 2030. These represent respective realistic build out percentages of 80% in 2020, 82% in 2025, and 85% in 2030.


For more information on the Summit County build-out analysis, contact Kate Berg in the Summit County Planning Department at 970-668-4204.