Carriage Houses & ADUs in Nanaimo: Cost, Permits, Rules & Building Guide (2026)

With housing costs continuing to

rise and more families looking for flexible ways to use their property, carriage houses and accessory dwelling units (ADUs) are becoming an increasingly popular option for Nanaimo homeowners.

Whether you're considering a detached home for aging parents, additional space for family, a long-term rental, or simply want to make better use of your property, an ADU can add significant functionality and long-term value to an existing lot.

But before you start designing, there are some important things to understand about building an ADU or carriage house in Nanaimo.

What Is an ADU or Carriage House?

An Accessory Dwelling Unit (ADU) is a smaller, independent residence located on the same property as a primary home.

In Nanaimo, you'll hear several terms used when talking about these types of homes, including:

• Carriage house

• Carriage home

• Garden suite

• Laneway house

• Accessory dwelling unit (ADU)

• Secondary suite in an accessory building

Whatever you call it, the basic idea is the same: creating an additional self-contained living space on your property.

Can I Build a Carriage House on My Property in Nanaimo?

Possibly — but this is something you should determine before paying to have a building fully designed.

Your property's zoning, lot configuration, existing buildings, setbacks, building height, lot coverage, parking, servicing and other requirements can all affect what you're able to build.

Then there are the physical characteristics of the property itself.

Nanaimo has plenty of properties with rock, slopes, difficult backyard access and existing services that weren't originally installed with another dwelling in mind.

A property may technically allow an ADU while still presenting construction challenges that significantly affect the project's cost.

That's why one of the first steps should be answering two questions:

Can we build it?

Does it make financial sense to build it?

2026 Nanaimo Carriage House & ADU Rules at a Glance

Before designing a carriage house or ADU, it's important to understand some of the basic City of Nanaimo zoning requirements.

Under the City's current zoning regulations, some of the key numbers homeowners should know include:

• Maximum accessory building area: In many common residential zones, the combined gross floor area of accessory buildings can be up to 100 m² (approximately 1,076 sq. ft.).

• Garage space: In certain situations, up to 42 m² (approximately 452 sq. ft.) used exclusively for parking may be excluded from the accessory-building floor-area calculation.

• Separation from the main house: An accessory building containing a secondary suite must generally be at least 3 metres from the principal building.

• Rear setback: In many residential zones, accessory buildings can have a rear-yard setback as little as 1 metre, although lane conditions and the property's specific zoning can change this requirement.

• Building height: Standard accessory-building height generally ranges from 4.5 m to 5.5 m, depending on roof pitch.

• Up to 7 m height: Certain accessory buildings can be permitted up to 7 metres high, including qualifying designs with a second-storey secondary suite.

These rules can make it possible to build a surprisingly functional home on an existing Nanaimo property — including designs that combine a garage or workshop with living space above.

However, these numbers shouldn't be treated as a guarantee that they apply to every property. Zoning, lot configuration, existing structures, lanes, setbacks, servicing and other site-specific requirements can change what's possible.

That's why we recommend reviewing the individual property before committing to a design.

How Much Does It Cost to Build an ADU in Nanaimo?

This is usually one of the first questions homeowners ask — and unfortunately there isn't one square-foot number that accurately answers it.

ADUs can actually be relatively expensive per square foot compared with larger homes.

That's because even a small home still needs many of the expensive components of a full-sized house:

• Kitchen

• Bathroom

• Foundation

• Plumbing

• Electrical

• Heating and ventilation

• Windows and doors

• Insulation and building envelope

• Appliances and fixtures

Then you have the property itself.

Excavation, rock removal, utility connections, drainage, driveway and access work, landscaping and electrical upgrades can have a major impact on the final project cost.

For that reason, we recommend developing a preliminary construction budget before getting too far into the design process.

Don't Forget About Site Costs

The building itself is only part of the overall ADU budget.

Site work can represent a significant portion of the project, particularly when you're building behind an existing home.

Before starting, it's worth looking at:

• Excavation requirements

• Rock

• Access for machinery

• Water service

• Sewer connection

• Stormwater management

• Electrical service

• Retaining walls

• Driveway or parking requirements

• Landscaping and site restoration

A beautiful 800-square-foot carriage house at the back of a property isn't much good to your construction budget if nobody considered how the excavator, concrete, materials and services were going to get there.

This is one of the reasons we believe involving a builder early in the process can be valuable.

What Size Carriage House Can I Build in Nanaimo?

There isn't one answer that applies to every property.

The allowable size and configuration of an accessory dwelling can depend on the zoning and characteristics of the property, as well as current City of Nanaimo regulations.

Setbacks, building height, lot coverage and separation from existing buildings can all influence the final design.

If you're starting with a specific property, the better approach is to review that property first rather than choosing an ADU plan online and trying to make it fit afterward.

Can I Build a Garage With a Suite Above It?

For some properties, this can be an excellent option.

Combining a garage or workshop with living space can make better use of the building footprint while providing both additional storage and an independent living space.

However, adding a garage below a dwelling introduces additional design, structural, fire-separation and construction considerations.

It's something worth discussing during the initial design and budgeting stage rather than after plans have already been completed.

Do I Need a Building Permit for an ADU in Nanaimo?

Yes. Construction of a new carriage house requires a building permit from the City of Nanaimo.

Depending on the property and design, the process may also require building plans, site information and supporting documentation from various professionals.

A carriage house is much closer to building a small custom home than constructing a typical backyard accessory building.

The earlier these requirements are identified, the easier it is to incorporate them into the design, schedule and budget.

Don't Forget About Servicing

This isn't the exciting part of designing an ADU, but it can be one of the most important.

Where are the existing:

Water? Sewer? Storm? Electrical services?

And how will the new dwelling connect to them?

Existing services may sometimes be usable, while other properties may require additional work or upgrades.

Servicing should be considered at the beginning of the project because the location of existing utilities can even influence where it makes the most sense to place the new building.

ADU vs. Secondary Suite: What's the Difference?

A secondary suite is commonly located inside the primary residence, such as a basement suite.

A carriage house or detached ADU provides a separate building.

There are advantages to both.

An internal suite may be less expensive because you're working within an existing structure.

A detached ADU can provide considerably more privacy and independence, which may make it particularly attractive for multi-generational living, long-term rentals or family members.

The right option depends on your property, budget and what you're trying to accomplish.

Why Are Nanaimo Homeowners Building ADUs?

There isn't one reason.

Multi-Generational Living

Parents can live close to their children while maintaining their own independent space.

Adult Children

An ADU can provide a stepping stone between living at home and purchasing a property of their own.

Rental Income

A second dwelling may provide an additional source of long-term rental income.

Downsizing

Some homeowners may eventually choose to live in the smaller dwelling while making different use of the primary home.

Property Flexibility

Your housing needs today may be completely different 10 or 20 years from now.

A thoughtfully designed ADU gives a property more options.

Should I Design the ADU or Talk to a Builder First?

Ideally, design and construction budgeting should happen together.

One of the most frustrating situations for a homeowner is spending months designing exactly what they want, only to discover that it's substantially more expensive to build than expected.

Getting construction input early means the design can take into consideration:

• Overall budget

• Site access

• Foundation options

• Structural requirements

• Servicing

• Material choices

• Buildability

• Energy efficiency

• Long-term operating costs

It's much easier — and usually much less expensive — to make adjustments while something is still a drawing.

What Should I Do First?

If you're thinking about building a carriage house or ADU in Nanaimo, you don't necessarily need completed plans to start the conversation.

Start with the property.

Determine what's permitted, look at where the building could realistically sit, consider site access and servicing, and establish a preliminary construction budget.

From there, you can move into design knowing you're working toward something that can actually be built.

Thinking About Building a Carriage House or ADU in Nanaimo?

Velsen Homes works with homeowners throughout Nanaimo and the surrounding Vancouver Island communities on custom homes, carriage houses, ADUs and residential construction.

We can help from the early stages of determining what's possible on your property through design, budgeting, permitting and construction.

Already have a property in Nanaimo? Send us the address and tell us what you're considering. We can help you determine what may be possible and the best place to start.