The B.C. government has announced changes to the building code that expand options for secondary suites in multi-family buildings.

The changes will give local governments the choice to allow secondary suites in side-by-side multi-family buildings such as duplexes, townhouses and row housing.

The changes do not apply to apartment-style buildings where units are above or below each other.

Housing Minister Selina Robinson says the changes will help create more affordable housing, while ensuring buildings in B.C. meet health, safety and energy-efficiency standards.

Size restrictions for secondary suites are also being removed from the provincial building code, which applies throughout B.C. except for some federal lands and the City of Vancouver.

The provincial code does not set a minimum size, which means local governments may set their own restrictions for secondary suites.

David Hutniak, chief executive officer of LandlordBC, says he supports the move because those secondary suites represent about two-thirds of all rental housing.

"We need more homes, more rental homes, and we're not building tons of purpose-built rental, which is really what we would like to see more of," he said.

It will be up to municipalities to decide whether to embrace the changes and amend zoning and development bylaws to allow the secondary suites.

Other recent code changes

Earlier this year, the province announced it was changing the building code to allow 12-storey wood buildings, up from the previous limit of six storeys.

Mass timber construction refers to buildings in which the primary load-bearing structure is made of solid or engineered wood. It has a reduced carbon footprint when the wood is sourced from sustainably managed forests, and these buildings can be one-fifth the weight of comparable concrete structures, the ministry says.

The province has also introduced new requirements for public-sector buildings as part of its energy step code, a voluntary standard for energy efficiency that local governments and builders can opt in to. Rather than specifying how to construct a building, the energy step code identifies an efficiency target and allows the builder to decide how to meet it.

There are now energy step code requirements for hospitals, schools, community centres and university classrooms, in part of an effort to make new buildings in B.C. net-zero energy ready by 2032, the province says.

The changes to the B.C. building code are set to apply to building permit applications on or after Dec. 12.