Denver Detached Garage Site Plan: Alley Access, Setbacks and Lot Coverage

A detached garage can add secure parking, storage and workspace to a Denver property. However, fitting one into an established residential lot requires more than selecting a convenient location. The garage must be evaluated against zoning rules, property boundaries, required setbacks, building coverage, utilities, drainage and vehicle access.

A clear Denver detached garage site plan brings these details together on a scaled drawing. It helps permit reviewers understand where the garage will be built, how vehicles will enter from the alley and how the project relates to the existing house and neighboring properties.

Does a Detached Garage Require a Permit in Denver?

Yes. The City and County of Denver states that all garages require zoning, building, and Sewer Use and Drainage Permits, commonly called SUDP permits. Depending on the garage design, separate electrical, plumbing or mechanical permits may also be necessary.

Projects that provide the information needed for zoning, building and SUDP review with the initial application may receive simultaneous reviews. Applications are submitted electronically through Denver’s e-permits system.

Current application instructions and document requirements are available on Denver’s official Residential Garages permit page.

Why the Site Plan Matters

The site plan is the drawing that connects the garage design to the actual property. Floor plans and elevations describe the building itself, while the site plan explains where the building will sit on the lot.

Denver specifically instructs applicants to prepare the site plan to scale and include a north arrow. The plan should show and dimension:

• All zone-lot lines;
• Adjacent streets and alleys;
• Existing buildings and driveways;
• The proposed garage and its height;
• Distances between the garage, lot lines and existing structures; and
• New driveway locations and dimensions, when applicable.

For the SUDP review, Denver also asks applicants to identify the size, type and location of water, sanitary-sewer and storm-sewer lines on the site plan.

What Should a Denver Detached Garage Site Plan Show?

1. Property and zone-lot lines

Start with the legal boundaries of the property. Show the front, side and rear zone-lot lines and include available dimensions. The street and alley should be labeled so the orientation of the property is immediately clear.

An existing fence should not automatically be treated as the legal boundary. Fences may be offset, shared or installed without a survey. Denver states that a property survey is necessary when proposed construction is within three feet of a property line. The City requests a boundary survey for vacant land or an improvement survey when existing structures are present.

2. Existing house and improvements

Show the footprint of the existing house along with other relevant improvements, such as:

• Existing garages, sheds and accessory structures;
• Driveways, parking pads and paved areas;
• Patios, decks and covered areas;
• Fences, retaining walls and gates;
• Walkways and steps; and
• Utility meters or visible service equipment.

Clearly label existing features so they cannot be confused with proposed construction.

3. Proposed garage

Draw the proposed garage footprint to scale and provide its outside dimensions. Label it as “proposed detached garage” and show its distance from each nearby property line, the house and other structures.

The site plan should also state the proposed building height. Separate architectural elevations and construction plans will usually provide more detailed information about wall height, roof shape, materials, doors, windows and foundation construction.

4. Garage doors and vehicle approach

Show which direction the garage doors face. This is especially important where the garage will be accessed from a rear alley.

The driveway or apron between the garage and alley should be wide enough to explain the intended vehicle path. Do not show only the garage footprint and leave the reviewer to guess how a vehicle will reach it.

5. Utilities and drainage

Identify known water, sanitary-sewer and storm-sewer lines. If the garage will contain a sink, bathroom, floor drain or other plumbing, additional utility information may be required.

The plan should also identify relevant grading and drainage conditions. Avoid locating the garage where its foundation or driveway will block an established drainage path without providing an appropriate solution.

How Does Rear-Alley Access Affect the Plan?

Rear alleys are common in many Denver neighborhoods and often provide the most practical access to a detached garage. The alley should be shown as more than a simple label. The plan should explain how the garage connects to it.

Useful alley-access information includes:

• The location and width of the alley;
• The rear property or zone-lot line;
• The garage-door location;
• The driveway or paved apron between the garage and alley;
• The distance from the garage to the rear lot line;
• Existing utility poles, overhead lines and service equipment;
• Fences, gates and trash-storage areas; and
• Nearby structures that may restrict vehicle turning.

If a project includes a new or modified driveway connection or curb cut, Denver advises that transportation engineers may evaluate the adjoining public infrastructure, including alleys, sidewalks and curb ramps. Improvements to nearby public right-of-way may be required in some circumstances.

A conventional rear-alley garage does not normally need a curb cut from the front street, but the site plan should still show the existing front driveway if one is present.

Denver Garage Setbacks Are Property-Specific

There is no single garage setback that applies to every Denver property. The required location depends on the zone district, neighborhood context, lot configuration, building form, alley conditions and any applicable overlays or special zoning provisions.

The Denver Zoning Code organizes many districts according to neighborhood contexts, including suburban, urban edge, urban, general urban and urban center. These contexts address factors such as building placement, height, street patterns and alley patterns.

Before putting setback dimensions on the plan:

1. Confirm the property’s current zone district;
2. Identify the applicable detached-accessory-structure building form;
3. Review side, rear and street-facing setback standards;
4. Check whether an alley changes the applicable rear-lot standard;
5. Check for overlays, waivers, conditions or planned-unit-development rules; and
6. Measure the proposed garage from the correct zone-lot lines.

Denver’s zone district descriptions explain how Denver’s zoning abbreviations work and provide links to the applicable zoning-code articles.

Do not copy a setback from a neighboring project. Two nearby properties can have different zoning, lot-line conditions or recorded restrictions.

What Is Lot Coverage?

Lot or building coverage measures how much of the zone lot is occupied by building footprints and other features counted by the applicable zoning rules. Adding a detached garage increases the developed area of the property and can bring an already improved lot closer to its permitted limit.

A basic coverage calculation generally starts with:

• The total zone-lot area;
• The existing house footprint;
• Existing accessory-building footprints;
• The proposed garage footprint; and
• Other features included by the applicable definition.

The maximum allowed coverage is not the same in every Denver zone district. The definition of what must be counted should also be verified before preparing the calculation.

A useful site plan can provide a simple existing-and-proposed coverage table:

Use verified property dimensions and the current zoning-code definitions rather than estimating coverage from an online aerial image.

Drainage and Sewer Review

Denver requires a Sewer Use and Drainage Permit review for residential garages. The SUDP team reviews development projects for matters that can include sanitary sewer, storm drainage, grading, floodplain conditions, groundwater and effects on public or private property.

The City’s official Sewer Use and Drainage Permits page provides current residential submittal guidelines and a specific resource for detached garages.

Depending on the project, the plan may need to show:

• Existing and proposed grades;
• Surface-drainage directions;
• Downspout discharge locations;
• Sanitary- and storm-sewer lines;
• Existing drainage paths or swales;
• The garage’s finished-floor elevation; and
• The slope of the driveway or alley apron.

The garage and driveway should be planned so they do not unintentionally trap water against the house, direct runoff into the garage or obstruct an established drainage path.

Additional Conditions to Check

Historic districts and landmarks

A garage on a designated landmark property or within a historic district may require a certificate of appropriateness. Denver recommends obtaining the certificate before applying for the building and zoning permits.

Parkway setbacks

Properties along designated parkways can have additional setback considerations. An exception request may be necessary when work encroaches into a parkway setback.

Public trees

If public right-of-way trees could be affected by construction or access, contact the Office of the City Forester. Tree trunks, root areas and low branches can affect machinery access even when the garage itself complies with zoning.

Demolition

If an existing garage or accessory building will be removed first, Denver advises that a separate demolition permit is required. Show the structure as “existing to be removed” rather than leaving it off the plan.

Overhead utilities

Rear alleys frequently contain utility poles and overhead lines. Show known utility features and confirm required clearances before fixing the garage height, roof design or construction route.

Typical Denver Garage Permit Planning Process

1. Research the property. Confirm the address, zone district, landmark status and other mapped conditions.
2. Obtain property documents. Gather the survey, recorded plat and available utility information.
3. Develop the garage concept. Decide its size, height, roof form, door orientation and intended use.
4. Check zoning constraints. Review setbacks, coverage, permitted building form and alley access.
5. Prepare the site plan. Show the lot, existing improvements, proposed garage, dimensions, utilities and access.
6. Prepare construction drawings. Provide the foundation, framing, roof, exterior materials and other required details.
7. Submit through e-permits. Denver instructs garage applicants seeking zoning, building and SUDP review to select the “building log” permit type and the “new accessory structure” project scope.
8. Respond to comments. Correct drawings or provide missing information requested by reviewers.
9. Activate the permits. Construction should not begin until the necessary permits are issued and active.
10. Schedule inspections. Follow the approved plans and arrange all required construction and trade inspections.

Common Site-Plan Problems to Avoid

• Using a fence as the legal boundary without verification;
• Leaving the rear alley off the drawing;
• Showing a garage door without a usable vehicle approach;
• Copying setbacks from another Denver property;
• Omitting the garage height;
• Failing to show distances to the house and lot lines;
• Ignoring existing sheds or accessory structures in the coverage calculation;
• Leaving water, storm and sanitary-sewer lines off the SUDP plan;
• Failing to identify an existing structure that will be demolished; and
• Submitting architectural plans that do not match the site-plan footprint.

Frequently Asked Questions

Can I use an aerial image as my Denver garage site plan?

An aerial image can provide helpful background information, but it does not reliably establish legal property lines or exact distances. Denver requires a scaled site plan with dimensions, labels and a north arrow.

When does Denver require a property survey?

Denver’s residential garage guidance states that a survey is necessary when construction is proposed within three feet of a property line. Confirm the current requirement for your specific project before ordering survey work.

Does the driveway need to appear on the plan?

Yes. Show existing driveways and any proposed driveway or alley apron. For a new driveway, Denver requests its width, construction material and dimensions to property lines and adjacent driveways.

Is lot coverage the same as floor area?

No. Lot coverage generally concerns the area occupied at ground level, while floor area can include usable space on multiple levels. Both terms should be calculated according to the definitions in the applicable zoning code.

Does a site plan guarantee permit approval?

No. The site plan is one part of the application. Approval depends on the complete design, applicable zoning, building and drainage requirements, and the City’s review.

Prepare a Clear Denver Detached Garage Site Plan

A successful garage plan should clearly explain how the new structure fits on the property. It should show the legal lot configuration, existing house, proposed garage, alley connection, setbacks, lot coverage, utilities and drainage conditions in one coordinated drawing.

Checking these constraints before construction drawings are finalized can reveal layout problems while the garage is still easy to reposition or resize.

Official Resources

• City and County of Denver — Residential Garages
• City and County of Denver — Zone District Descriptions
• City and County of Denver — Denver Zoning Code
• City and County of Denver — Sewer Use and Drainage Permits
• City and County of Denver — E-permits

This article provides general information only. Zoning, permit and drainage requirements can change and vary by property. Confirm current requirements with the City and County of Denver before beginning design or construction.