Austin Maynard Architect's was awarded the commendation for the "character-filled" extension in the residential alterations and additions category.

The Victorian-based architecture firm started working with the clients on the project in 2015 and chose to sympathetically extend the 1951 bungalow instead of demolishing it.

Dubbed Empire, for its location on Empire Circuit, twin pavilions were added to the home, the two additions include a kitchen and dining area and a master suite.

The pavilions were attached to the existing residence through hand-crafted metal shingles with Canberra-based Preferred Builders behind the build.

The national jury described the project as "deftly executed" and said it was "an intelligent response to the larger issues of suburban living".

"Initial design decisions and confident planning approaches have energised the existing post-war home by creating clear sight lines through a logical and curated sequence of interconnected spaces," jury comments said.

"Empire creates a conversation between old and new that can be appreciated at every level."

It is not the first award for the Forrest extension, with Austin Maynard Architects taking away the Canberra Medallion at the ACT awards earlier this year. Previous Medallion winners include iconic Canberra buildings such as the High Court and the Australian National Gallery.

Australian Institute of Architects ACT executive director Liz Lang said she was proud to see a Canberra home receive national recognition.

"Empire shows how architects can help home owners revitalise their suburban homes," she said.

Cox Architecture's Edgeworth Apartments in Turner was also a finalist in the national awards, vying for a going in the multiple housing category.

The awards were held in Brisbane on Thursday night.