Home Additions Hub · Sub-guide 3 of 4

Permits, warranty and the 75% rule.

This is the page the rest of the hub points at. One threshold decides whether your addition is a renovation or, in the eyes of BC law, a brand new home.

Last reviewed September 2026

Interior entry hall of a custom home with a double-height wall, a floating shelf, pale wide-plank flooring and a grey open-riser staircase with glass railings leading to an upper floor — The stair connecting two floors of an Icon build. On an addition, the question of how much new structure sits above the foundation is what decides whether the finished house is legally new.

The short answer

The Homeowner Protection Act defines a new home to include a home that is or is being substantially reconstructed. BC Housing sets where that begins in Regulatory Bulletin No. 6: a home is substantially reconstructed when 25% or less of the original structure above the foundation remains, or when 75% or more of the reconstructed home is new. Once a project is over that line it is no longer considered a renovation and requires a New Home Registration Form, plus either proof that a licensed builder has arranged home warranty insurance or a formal exemption such as an Owner Builder Authorization.

How the test runs for an addition

Scenario 4 of Regulatory Bulletin No. 6 is written specifically for additions to pre-existing homes, and it runs in a fixed order. Skipping to the percentage is the common mistake, because the first question can settle the matter on its own.

Step 1
Does the addition create one or more additional units?
The bulletin makes this the first consideration. Everything after it depends on the answer.
Step 2
If it creates a legal secondary suite: no form required.
The bulletin is unambiguous here. An addition that produces a legal secondary suite does not require a New Home Registration Form, regardless of how the size arithmetic would have come out.
Step 3
If it creates a duplex or triplex: a form is required on the new unit.
Where the addition produces a separate dwelling of that kind, the New Home Registration Form attaches to the new unit the addition created, not to the whole property.
Step 4
If it creates no new unit: the 75% rule applies.
Only now does size decide it. The bulletin gives the measurable form: if the new portion of the construction is at least three times the size of the original structure remaining, and therefore 75% of the whole, the home is substantially reconstructed.

There is a separate, lower threshold for the second storey case. Where the foundation is new as well, Scenario 2 treats 50% or more of new above-foundation structure as substantial reconstruction. That case is worked through in the second storey sub-guide.

What crossing the line actually changes

The consequence is not paperwork. It changes who is legally permitted to build your addition.

The Homeowner Protection Act defines a residential builder as a person who engages in, arranges for or manages all or substantially all of the construction of a new home, or agrees to do any of those things, and the definition expressly includes a developer and a general contractor. Because a substantially reconstructed home is a new home under the Act, the person managing that work is a residential builder and has to hold a licence. A renovation contractor who is not licensed as a residential builder can take on a renovation. The same contractor cannot take on the same project once it has been reclassified.

This is why the question belongs at the start of a project rather than at permit stage. An owner who has signed with a contractor, paid for drawings and then discovers the scope has drifted over the threshold is choosing between reducing the scope and replacing the builder.

The permits, and what they do not cover

Burnaby requires a building permit for any construction project involving the excavation, erection, enlargement, alteration, removal, fire repair or demolition of any building or structure, including accessory and temporary buildings. An addition is captured by the City's own definition: any change to a building's footprint or an increase in floor area.

The form to use is the Building Permit Application for Additions and Alterations to Existing Residential Buildings, revised 5 May 2025 and submitted through the City's My Permits Portal. It lists Addition and Floor Addition as separate scopes, marks an Engineering Pre-Application as required, and asks on its face whether a demolition permit or a tree permit is needed.

One line on that form catches people out. It states that separate permits are required for electrical, plumbing, gas, heating installation, sprinkler permits and illuminated signs. An addition that adds a bathroom and moves a furnace needs several permits, not one, and each has its own timeline.

Settle this before the design is fixed

Best for

Running BC Housing's Substantial Reconstruction Online Query at concept stage
Projects where an addition creates a legal secondary suite, which the bulletin exempts from the form
Owners who want the classification settled before they choose a contractor
Scopes that stay well clear of the threshold, where a renovation contractor remains an option

Fails when

The scope grows through design without anyone re-testing the ratio
The contractor is chosen before the classification is known
An owner treats their own measurement as the final answer
The foundation is being replaced and nobody has checked Scenario 2's lower bar

Verify before acting

Have the civic address or PID, the local building department name and the proposed scope ready for the query
Ask any prospective builder whether they hold a BC Housing residential builder licence
Confirm whether the work creates a new dwelling unit, which changes the test entirely
Ask the City which separate trades permits your scope requires

BC Housing Regulatory Bulletin No. 6 states that each case must be examined on its own merits, that the final determination will be made by BC Housing, and that the bulletin does not constitute legal advice. Use this page to know which questions to ask, and BC Housing to get the answer.

Frequently asked questions

What is the 75% rule for home renovations in BC?

The 75% rule is BC Housing's threshold for substantial reconstruction, published in Regulatory Bulletin No. 6. A home is considered substantially reconstructed when 75% or more of the reconstructed home is new, or when 25% or less of the original structure above the foundation remains. Once a project crosses it, the home is a new home under the Homeowner Protection Act and stops being treated as a renovation.

What happens when my addition crosses the substantial reconstruction threshold?

Crossing the threshold means the project requires a New Home Registration Form. Beyond the form, BC Housing Regulatory Bulletin No. 6 states you will need either proof that a licensed builder has arranged home warranty insurance for the new home, or a formal exemption such as an Owner Builder Authorization. The practical effect is that not every contractor is legally able to take the job.

How does BC Housing measure the 75% for an addition?

For additions, BC Housing Regulatory Bulletin No. 6 expresses the test as a ratio you can measure. If the addition results in a home where the new portion of the construction is at least three times the size of the original structure remaining, it is 75% of the whole and the home is substantially reconstructed. The bulletin applies this only where the addition does not create a new dwelling unit.

Does an addition that creates a secondary suite need a New Home Registration Form?

No. BC Housing Regulatory Bulletin No. 6 states plainly that if an addition creates a legal secondary suite, a New Home Registration Form is not required. This is the first question the bulletin asks about any addition. If instead the work creates a duplex or a triplex, a New Home Registration Form is required on the new unit created by the addition.

Who is a residential builder under BC law?

Can I do the work myself if my addition counts as a new home?

Building it yourself is possible through a formal exemption rather than by default. BC Housing Regulatory Bulletin No. 6 names the Owner Builder Authorization as the alternative to proof that a licensed builder has arranged home warranty insurance. It is an authorization you apply for, not a status you assume, and it should be resolved before construction rather than discovered during a permit review.

Which permit does a home addition need in Burnaby?

Additions to existing homes use the City of Burnaby's Building Permit Application for Additions and Alterations to Existing Residential Buildings. The form lists Addition and Floor Addition as separate scopes of work, marks an Engineering Pre-Application as required, and asks whether a demolition permit or a tree permit is also needed. Applications are submitted through the City's My Permits Portal.

Does the building permit cover the electrical and plumbing work?

No. Burnaby's addition permit application states that separate permits are required for electrical, plumbing, gas, heating installation, sprinkler permits and illuminated signs. A building permit authorises the structural and building work. The trades permits sit alongside it, and an addition that adds a bathroom or relocates a furnace will need several of them.

How do I find out whether my project crosses the threshold?

BC Housing publishes a Substantial Reconstruction Online Query tool for an initial assessment. Regulatory Bulletin No. 6 says you should have the civic address or PID, your contact details, the name of the local building department, the building permit staff contact if available, and details of the proposed work. The bulletin notes some projects require a secondary assessment through BC Housing's Compliance Department.

Is the 75% rule something I can decide for myself?

No. BC Housing Regulatory Bulletin No. 6 states that each case must be examined on its own merits and that the final determination will be made by BC Housing. The bulletin also states that it does not constitute legal advice and directs readers to the Act and its regulations for complete details. Treat any calculation you run yourself as a planning estimate that BC Housing still has to confirm.

Official sources