Secondary suite
or coach house
in Chilliwack?

The Bill 44 SSMUH changes expanded what Chilliwack homeowners can legally build on qualifying lots. The most common question we now get is some version of: “Should I build a basement suite or a coach house?”

The short answer: it depends on lot size, existing basement conditions, your budget, and what you want the long-term outcome to be. The long answer walks through the real tradeoffs.

Quick definitions

A secondary suite is a self-contained dwelling unit inside the main home, typically in the basement. Separate entrance, separate kitchen, separate bathroom and bedroom, but sharing the building envelope with the main home.

A coach house (sometimes called a garden suite or laneway house) is a detached secondary dwelling in the backyard. It is a standalone structure with its own foundation, walls, roof, and full mechanical systems.

Cost comparison (Chilliwack 2026)

Secondary suite

$100,000 – $150,000

Conversion of existing basement space. Egress windows (typically two), fire separation, sub-panel, full kitchen and bathroom rough-in, separate entrance. No new foundation. No new roof.

Coach house

$300,000 – $500,000

Ground-up detached dwelling. New foundation, framing, envelope, roof, full mechanical (electrical, plumbing, HVAC), interior finish, exterior finish. Servicing trench for water, sewer, and electrical to the main services at the street or from the main house.

The cost difference (roughly $200K to $350K) reflects that a coach house is a new small house. A basement suite reuses the existing structure.

Rental income comparison

Chilliwack rental market 2026 data (informal, from listings):

• Basement suite, 1 bedroom: $1,500 to $1,900 per month
• Basement suite, 2 bedroom: $1,900 to $2,400 per month
• Coach house, 1 bedroom: $1,900 to $2,400 per month
• Coach house, 2 bedroom: $2,400 to $3,000 per month

Coach houses command a roughly $400 to $600 per month rental premium over equivalent basement suites because they offer more privacy, natural light, and a detached feel.

Simple payback math

Using middle-of-range assumptions:

• Basement suite: $125K build, $2,100/month rent = 5.0 year simple payback
• Coach house: $400K build, $2,700/month rent = 12.3 year simple payback

On pure payback period, basement suites win substantially. This is why basement suites are the more common call in Chilliwack when the main driver is income replacement or mortgage help.

But coach houses have a different value story. They add more to property resale value (often $200K to $300K versus $75K to $150K for a basement suite), they separate tenants from your living space, and they typically attract higher-quality long-term renters.

When a basement suite is the right call

• Your existing basement has adequate ceiling height (7 feet minimum under BC Building Code).
• Your lot is small or the backyard is already committed to landscaping or a pool.
• Your budget maxes out at $150K or so.
• You want faster payback and are comfortable sharing the building with tenants.
• You plan to use the suite as a mortgage helper now and convert back to family use later (basement suites can be reversed more easily than coach houses).
• Your property is not below Flood Construction Level. In Fairfield Island, Greendale, and lower Yarrow, FCL rules often block basement suites.

When a coach house is the right call

• Your lot is large enough to support the setbacks (typically 500 square meters minimum, and easier above 700).
• Your basement has inadequate ceiling height or active moisture issues.
• You have the budget ($300K to $500K).
• You want maximum privacy separation between tenant and owner.
• You are building for long-term rental or a multi-generational family setup (aging parents in the coach house is a common Chilliwack use case).
• Your property is below FCL and basement suites are not allowed.
• You see the coach house as a retirement plan: your rental income backup, or a place you might move into later while renting out the main house.

Permit path comparison

Secondary suite

• Building permit
• Electrical trade permit
• Plumbing trade permit
• Occupancy inspection at completion
• Typical processing: 10 weeks front-end, 10-16 weeks build

Coach house

• Development Permit (Development Permit Area 8 design guidelines)
• Building permit
• Electrical, plumbing, gas trade permits as applicable
• Servicing approval (water, sewer, electrical)
• Multiple inspections through the build
• Typical processing: 12-16 weeks front-end, 20-30 weeks build

Coach houses require more permit work because they are essentially a new house on the lot. Development Permit Area 8 has specific design guidelines around form, materials, and relationship to the main home that must be met.

The short-term rental question

BC's short-term rental legislation (effective May 2024) limits Airbnb-style rentals in Chilliwack to the owner's principal residence plus one secondary suite or coach house on the same property. The tenant cannot be short-term in a property that is not your principal residence.

What this means practically: both basement suites and coach houses are allowed for short-term rental if you live in the main house. Long-term rental is unrestricted.

Can you do both?

Under Bill 44 SSMUH, most qualifying Chilliwack lots over 280 square meters inside the Urban Growth Boundary can legally have all three: principal home + basement suite + coach house. That is three rental-eligible units on one lot.

Realistic combined build cost: $400K to $650K for the suite plus coach house on top of an existing home. Realistic combined gross rent: $4,000 to $5,400 per month. Simple payback: 8 to 11 years. This is a longer horizon than either option alone but produces a more substantial long-term income stream and higher property value lift.

The bottom line

For most Chilliwack homeowners with mortgage-helper or rental-income goals and adequate basement conditions, a secondary suite is the better choice. Lower build cost, faster payback, and reversible if your plans change.

For homeowners with larger lots, bigger budgets, and a longer time horizon, a coach house adds more resale value and separates tenant life from owner life completely. For the aggressive few, doing both is legally possible on qualifying lots and produces a substantial long-term outcome.

The right answer is the one your specific lot, home, and budget supports. A site visit tells us which configuration is feasible before you commit.