Design review comes first in Glendale
Glendale's permit guidance for residential additions lays out the order: research the development standards and the city's Comprehensive Design Guidelines, consult Planning about the level of design review, apply through the GlendalePermits portal for either a Design Review Exemption or a Pre-Application Review, obtain Glendale Water & Power clearance, and only then apply for the building permit. The city warns that a single-family building application submitted before planning approval will be voided.
The zoning code backs that up. Except where the Director of Community Development allows otherwise, Glendale does not accept a building plan check application for a project that requires design review until the plans conform to what the review authority approved. That is why we settle the massing, rooflines and windows of an addition with Planning before the structural and construction drawings are finished.
Which review your addition gets
In the ROS, R1R and R1 single-family zones, an addition may be exempt from design review when it adds less than 700 square feet of floor and garage area, adds no story, and does not increase a street-facing facade by more than 200 square feet of floor area. Additions are counted together over any two-year period, so two smaller additions in quick succession can add up to a review. Staff can still require review if a project looks incompatible with the neighborhood in setbacks, roof style, eaves, massing or materials.
Additions that do not qualify are typically reviewed administratively by the Director of Community Development. That includes adding a story when the addition sits in the rear 50 percent of the house and matches the existing home in colors, materials, roof style and architectural treatment. Projects outside those limits go to the Design Review Board, and the Director can send a project to the board if staff find it incompatible with the neighborhood.
Size limits in Glendale's single-family zones
Glendale caps floor area by district. Single-family lots in floor area District I, II or III may build to 0.30, 0.40 or 0.45 of the first 10,000 square feet of lot area, plus 0.10 of any lot area beyond that, and in the hillside ROS and R1R zones, lots with an average slope of 40 percent or more are held to the District I ratio. Up to 500 square feet of garage is left out of the count for homes under 3,500 square feet, or up to 700 square feet for larger homes.
The code also typically limits lot coverage to 40 percent and requires at least 40 percent of the lot to remain permanently landscaped open space. In the R1 zone, which covers the city's older and flatter residential areas, a house may not exceed 25 feet in height, plus 3 feet for a roof with at least a 3 in 12 pitch. Hillside lots in the ROS and R1R zones are reviewed against the city's hillside design guidelines, and on sites averaging more than 50 percent slope, or where grading will exceed 1,500 cubic yards, the review authority can add conditions on haul routes and tree protection.
Additions in Glendale's historic districts
Glendale has nine designated historic districts: Ard Eevin Highlands, Brockmont Park, Casa Verdugo, Cottage Grove, Niodrara Drive, North Cumberland Heights, Rossmoyne, Royal Boulevard and South Cumberland Heights, with Cleveland Knoll listed as pending as of 2026. In these districts, design review is handled by the Historic Preservation Commission or the Director of Community Development instead of the Design Review Board.
Among other triggers, the code treats an addition of more than 200 square feet visible from the street, one of 700 square feet or more out of public view, or any added story as a major alteration, and for street-visible major alterations the Director decides whether the Commission or the Director reviews the project. Smaller additions are generally minor alterations reviewed by the Director. Planning an addition at the rear, below those thresholds, often keeps a project away from a Commission hearing.
Utilities, parking and protected trees
Glendale Water & Power requires both electric and water approvals for residential additions, and it asks applicants to contact it before formal plan check with a dimensioned site plan that shows every structure, power pole and power line. Required clearances from overhead lines and any utility easement can affect where an addition may go, so we resolve them early. If the existing house is nonconforming under today's zoning, enlarging its floor area brings the city's parking requirements into play as well.
Glendale protects indigenous trees: California live oak, scrub oak, San Gabriel oak, valley oak, mesa oak, California bay and California sycamore with a trunk six inches or more in diameter at 54 inches above the ground. A permit is required to cut, remove, relocate or encroach on one, and the protected zone generally reaches one foot past the dripline, or one foot out from the trunk for each inch of trunk diameter if that is larger, as the city determines. Footings, trenching and material storage all count, so we map these trees before siting an addition.
How we build a Glendale addition
We start with a site visit and the property's zoning, then sketch options that fit the review level you want to aim for. Once Planning signs off, we complete the structural design, coordinate the utility approvals and carry the project through plan check, inspections and final. You receive a written scope and price before construction starts.