Boulder County moves to cap home sizes with tiered approach

On Sept. 17, 2024, the Board of County Commissioners (BOCC) authorized the Community Planning & Permitting staff to pursue text amendments to the Site Plan Review (SPR) regulations in Article 4-800 of the Boulder County Land Use Code.

The Board expressed concerns about the increasing home sizes, the rate of change by which they are increasing in unincorporated Boulder County, and how these increases impact neighborhood character, sustainability, and affordability. The proposed amendments are now set for hearing before the Boulder County Planning Commission on Wednesday, March 19. Information on how to participate will be available here one week in advance of the hearing.

The Commissioners directed staff to explore reducing the current compatible size from 125% of the median of a defined neighborhood to the median of a defined neighborhood; changing what is currently a size presumption (that allows more floor area in certain circumstances) to a size limitation; and clarifying the regulations to improve processes, increase the public's ability to better navigate the regulations, and provide greater certainty of outcomes for applicants.

The current SPR regulations dictate a presumed compatible size that is equal to 125% of the median Residential Floor Area (RFA) for the defined neighborhood. Staff proposes to eliminate the size presumption and replace it with a structure size limit that is equal to the median RFA. The structure size limit will apply unless a development proposal significantly conflicts with the SPR standards as determined by the Director of Community Planning & Permitting, in which case, the Director may limit the RFA to an amount less than the maximum.

Parcels in the mapped Townsites of Allenspark, Eldora, Eldorado Springs, Raymond, and Riverside would still be limited to 1,500 square feet of RFA under the proposed regulations. For other properties, the allowable expansion varies based on the existing floor area as of Jan. 1, 2025.

Properties with an existing RFA of 1,500 square feet or less would be permitted to add up to 1,000 additional square feet or expand to the median size for their neighborhood, whichever is greater. Those between 1,501 and 3,000 square feet would be allowed an additional 750 square feet or expansion to the neighborhood median, whichever is greater.

For larger homes between 3,001 and 4,500 square feet, an additional 675 square feet or expansion to the neighborhood median would be permitted, whichever offers more space. Homes that exceed 4,501 square feet would only be allowed to expand up to the neighborhood median, with no additional floor area allocation beyond that limit.

Exemptions include properties with Conservation Easements, where the easement or land use agreement permits a larger floor area than the median neighborhood size. For properties with existing structures that exceed size limits but haven't been previously restricted through county land use approvals, a one-time addition of up to 200 square feet is permitted.

Other exemptions include the deconstruction and rebuilding of legally existing residential floor area, accommodations for energy efficiency improvements or the use of energy-efficient building materials, and special provisions for historic structures. Properties with landmarked or protected historic buildings may be allowed to exempt these structures from counting toward the overall RFA threshold for the parcel.

Under the current SPR regulations, applicants may be allowed to exceed the presumed compatible size if they have two or more immediately adjacent neighbors with RFA exceeding the presumed compatible size. Staff proposes to eliminate this ability to seek a larger size based on adjacent neighbors.

Under the current regulations, applicants may request additional RFA on their parcel by demonstrating mitigation of visibility impacts. Staff proposes to remove this exemption.

Small structures such as sheds (up to 400 square feet) that don't require building permits under Article 17 will no longer count toward a property's RFA calculations, providing homeowners more flexibility in land use.

This zoning amendment exempts permit-free small structures (up to 400 square feet) from RFA calculations while modifying SPR requirements. Converting to single-unit dwellings no longer triggers review, but exemptions for energy efficiency improvements or historic structure modifications now require formal site plan review.

The proposed amendments introduce "expedited" language to replace confusing "waiver" terminology, clarifying that some review is still necessary. This expedited process will apply to conservation easement projects (with easement holder approval) and one-time 200-square-foot additions. The changes also extend administrative timelines, increasing the referral periods slightly.

SPR appeals will remain under the Board of County Commissioners' authority, and the Board of Adjustment cannot grant variances from floor area maximums. Article 19 is updated to ensure Marshall Fire rebuilds remain governed by regulations in effect at the time of the fire until Article 19-500 expires.

To be included in the staff packet for the Planning Commission hearing on March 18, responses are due to longrange@bouldercounty.gov no later than Tuesday, March 11. Responses received after this deadline will be shared with the Planning Commission and incorporated into the staff packet for the BOCC hearing.