Capitol Hill Windows: Landmark Rules & Storms

Across most of Denver, replacing a window with one the same size is a no-permit job. Denver's building code exempts replacement of windows and doors with no structural alterations and no change in opening size in one- and two-family homes and townhouses. Capitol Hill is where that exemption most often doesn't apply. The neighborhood and its edges hold several historic districts, including Quality Hill, Pennsylvania Street, Sherman-Grant, Humboldt Street, Swallow Hill and Wyman, along with individual landmarks, and Denver's code says that when a structure is a designated landmark or in a district designated for preservation, a building permit and approval from the local preservation authority shall be required.

For a Capitol Hill owner, that changes the order of operations: check designation first, then talk to Landmark Preservation, and only then shop for windows.

Is your building designated?

District boundaries are drawn block by block, so a house on one side of a street can be designated while its neighbor is not. Many Capitol Hill buildings are apartments or condos, and the rules apply to them too. Look up your address on Denver's landmark maps or ask Landmark Preservation staff before you collect bids.

What Denver's 2026 guidelines say about windows

Denver's design guidelines for landmark structures and districts took effect March 3, 2026. For character windows, the original or historic windows that define a building's appearance, the guidelines start from repair:

• Preserve and repair character windows on all facades. Repairs can include reglazing, patching and splicing in replacement elements.
• Keep the components: frames, sashes, divided-light patterns, mullions, sills, heads, jambs, moldings, transoms and sidelights.
• Don't cover historic window materials with trim wrap, and don't enclose historic transoms or sidelights.

Replacement may be considered if character windows are severely deteriorated. When it's approved, the new windows should:

• match the size, type, profile and design of the originals, and sit at the same depth in the wall;
• replace wood with wood or aluminum-clad wood, and steel or aluminum with the same; fiberglass composite may be considered if it closely replicates historic profiles and dimensions;
• not use vinyl or vinyl composite;
• use true divided lights or simulated divided lights with a spacer bar where divided lights exist, since grilles only between the panes aren't allowed;
• use clear or nearly clear low-E glass with a minimum 65% visible light transmittance and a maximum 25% reflectivity;
• reuse or replicate specialty glass such as leaded or stained glass.

On primary elevations, the guidelines also say not to use perimeter infill framing to create smaller windows within historic openings, a common shortcut in insert replacements.

Storm windows: the no-review option

The guidelines say the Landmark Preservation Commission doesn't need to review or approve storm windows, because storm windows don't require a permit. Denver encourages exterior storm windows as thermally efficient, cost-effective and reversible, and they let you keep the original windows. To minimize their visual impact, choose a color that matches the existing trim and line up the storm's meeting rails with those of the historic sash.

For many Capitol Hill owners, restored original sashes plus well-fitted storms deliver much of the comfort of new windows, without the cost of custom wood replacements or a design review.

How to plan a Capitol Hill window project

1. Confirm designation and whether your windows are character windows.
2. Get a condition assessment from a window restoration specialist. Severely deteriorated windows are the case where replacement may be considered.
3. Talk to Landmark staff before ordering anything, and submit for design review with product details if you're replacing.
4. Apply for the building permit with Landmark approval in hand.
5. Hire lead-safe. Most Capitol Hill buildings predate 1978, and paid contractors disturbing painted window parts must follow the EPA's lead-safe work rules.

For general window costs and products, see our window replacement guide. For the neighborhood's other rules, see the Capitol Hill area page.