Landmarks Board approves rear accessory building at 600 Spruce Street with conditions

The Boulder Landmarks Board on Jan. 8 voted unanimously to approve a landmark alteration certificate for a new accessory building at 600 Spruce Street, a contributing property in the Mapleton Hill Historic District. The board approved the roughly 726‑square‑foot, one‑and‑a‑half‑story structure with a set of conditions addressing retaining‑wall materials, driveway surfacing and garage door design.

The board’s unanimous approval followed a staff presentation finding the proposal “meets the standards for issuance of a landmark alteration certificate” and is generally consistent with Mapleton Hill design guidance if several conditions are met, Claire Brandt, the city’s historic preservation planner, told the board.

Why it matters: The accessory building would be placed at the rear of the lot and is intended to be subordinate to the primary house, preserving the front yard character of the Mapleton Hill block. Board members and members of the public raised concerns that concrete engineered retaining walls and a solid concrete driveway would create a modern, wall‑like presence in a narrow alley and would overwhelm the human scale and historic materials in the alleyscape.

Staff said the 726‑square‑foot building is proposed with lime‑washed brick cladding, aluminum‑clad windows, and a moderately pitched gable roof. The application shows an exterior concrete stair, engineered concrete retaining walls up to roughly 10–13 feet where the lot grades down to the alley, and a single large overhead garage door on the alley side. Staff recommended approval with conditions, including that retaining walls be redesigned to reflect the character and dimensionality of existing stone walls in the alley and that the driveway use permeable materials (for example, crusher fines, flagstone or brick) rather than poured concrete.

Applicants Hal and Skyler Bailey told the board they are open to alternatives for the retaining walls and said they would explore stonework or tiered walls; Hal Bailey said the alley turn and existing site conditions make a pair of single garage doors potentially impractical. “I don’t see how that’s really possible,” Hal Bailey said when asked about adding two single garage doors instead of one overhead door.

Board members pressed for more detailed design information as conditions of approval. The final condition set adopted by the board requires the applicant, prior to building permit submittal and subject to review by the Landmark Design Review Committee (LDRC), to: revise wall design to transition and visually blend with existing walls and topography; explore terraced walls with a maximum riser in the 36–42‑inch range where feasible; match materiality and dimensional character of historic stone in the alley; document lintels and base detailing for window and garage openings; explore connecting the retaining wall into the accessory building corner; demonstrate whether two single‑car doors are practicable for the alley turn (or document why they are impractical); and provide materials details for the driveway, garage door and exterior lighting.

The board recorded a roll call vote on the motion moved by Ronnie Palusio and seconded by John Decker. John Decker, Renee Golubic, Ronnie Palusio and Chair Abby Daniels voted yes; the motion carried unanimously.

What happens next: City council has 16 days to call up the decision. If council does not call it up, the LDRC will review the items required by condition and the landmark alteration certificate will be issued after the LDRC signs off. Claire Brandt said staff will circulate the LDRC packet and coordinate the detailed conditions with the applicants and the LDRC.

Ending: The board’s approval seeks to balance the property owner’s desire for an alley‑facing accessory building and the preservation of the alley’s historic character by requiring final design adjustments to the walls, driveway surface and openings before permits are issued.