Building In Boulder County - Presumptive Size

Fänas recently published a brief pamphlet on what property owners should be aware of when building in Boulder, Colorado. As noted, this was an overview intended to point out the many steps required throughout the process. We’ve gotten great feedback and thought we would elaborate on a few of the more important points that were not thoroughly detailed.

Building in Boulder County – How many square feet am I allowed to build?

This is always one of the first questions that should be asked and researched when planning to build in Boulder County. The first thing to be aware of is:

-You must physically go to the County Planning Department to have this questioned answered.

-You cannot find the answer online.

-You cannot figure it out based on the size of the property, the address, or what is built nearby.

The reason for this is because the maximum square footage you will be allowed to build is based on how it relates to the “neighborhood” in which it is being built. “Neighborhood” is intentionally put in quotes because it is this piece of the equation that the County defines for you and why you must meet with them to understand their definition.

When you meet with the County planner, they will ask you for the address of the property and will give you the following information:

-The zoning for the property

-Make you aware of any easements or other legal items related to the property

-The “neighborhood” the property is defined within

-The presumptive size* allowed for the property

-Any other applicable information important to know about the property (i.e. – it is in an extreme wildfire zone, etc.)

Presumptive Size:

Basically this states that the maximum allowable square footage for the new structure on the property cannot exceed 125% of the median square footage of the structures in the defined neighborhood. This is the maximum allowable square footage allowed for your property unless you are able to prove the size presumed is not compatible in other ways with the neighborhood.

The most straight forward way to request additional square footage than the presumed is to calculate the average square footage for (2) properties that share a property line with the property in question (assuming these are larger than the median square footage of the neighborhood). The average of these two properties can be used as the maximum square footage for the new property.

The complete list of circumstances that will be considered by the County to increase the maximum allowable floor area include: (re-printed from Section 4-806 of the Site Plan Review Standards – Boulder County Forms and Applications)

(A) The visibility of the proposed development from other private parcels within the defined neighborhood, as well as visibility from either public roads or open space both within and outside that defined neighborhood.

(1) The proposed development must be minimally visible from the above-listed areas. Mitigation of visibility impacts may be achieved by:

(a) the use of natural topography to screen the proposed development, or

(b) underground construction to screen the proposed development; existing underground residential floor area may be considered, or

(c) distance of the proposed development from other private parcels, public roads and open spaces.

(B) The distribution of residential floor area within the defined neighborhood, taking into consideration the sizes (a minimum of two) adjacent to the subject property.

(1) If the proposed development is able to overcome the size presumption due to the adjacent sizes, the size of the resulting development may not exceed the median residential floor area of those adjacent to the subject property that are over the size presumption.

(C) For properties which are encumbered by a Boulder County conservation easement that specifies an allowable house size on that parcel, that specified home size is a factor to be considered in rebutting a size presumption which is smaller than the house size defined in the conservation easement.

(D) Significant adverse impacts demonstrated according to Standards 3 through 16 of this Section 4-806.A.

(E) Demolition and rebuilding of legally existing residential floor area that is not in conflict with the other standards set forth in this Section 4-806.

(F) Retrofitting of an existing structure for purposes of making a demonstrated energy efficiency improvement.

(G) Existing residential floor area that already exceeds the size presumption and has not been approved through a prior County land use approval.

(1) Up to a one-time maximum of 200 square feet of residential floor area may be granted under this factor.

(H) Historic structure(s) that are landmarked or otherwise protected cause the residential floor area to exceed the size presumption.

The square footage for the project is required to be listed in the drawings and documents required for the Site Plan Review submittal (required for all new construction projects of any size). The County will verify your calculations at this step in the procedure and again before issuing a building permit.

At Fänas Architecture, we are happy to help you through the building process, especially with the nuances of building in Boulder County. Contact us at 303.444.5380 or if you have any questions, or download our free e-book with more helpful information.