Two-bedroom granny flat designs: what fits on a Brisbane block

We are asked about granny flats more each year: for parents, for adult children who cannot yet buy, and increasingly as a rental now that Queensland allows a secondary dwelling to be let to people outside the household. Two bedrooms is the size that most people settle on, because one bedroom is a studio and three is a house. This is what we tell people at the first meeting.

The rules, briefly

Brisbane City Council treats a secondary dwelling as part of the main house, not a separate lot. That means a cap on its floor area, a requirement that it sits on the same block with the main house and shares the address, and the usual setbacks and site cover limits. The cap is in the order of eighty square metres of floor area, though the exact number and the conditions depend on the zoning and change with the planning scheme, so we confirm it for your block in the plan stage before a line is drawn. Character overlays and flood mapping also apply. None of this is a barrier. All of it decides the design.

Two bedrooms in eighty square metres

A workable plan is a living, kitchen and dining room across the front of about thirty square metres, two bedrooms of ten to twelve each, a bathroom that also holds the laundry, and a hall no longer than it has to be. That leaves nothing spare, so every wall carries storage: a wardrobe that backs onto the linen cupboard, a kitchen with the fridge and pantry in one run, a bathroom with the washing machine under the bench. The plan is more like a good apartment than a small house.

The deck is the third room

In Brisbane the living area can be small if it opens onto a covered deck of the same width. For eight or nine months of the year the deck is where people sit, and it does not count toward the floor area in most cases. It should face north or east, away from the main house's windows, with a roof, a fan and a screen from the neighbours.

Where it goes on the block

The flat wants its own entry from the street or the side path, not through the main house's yard, and the two dwellings want to look at different things. On a standard block that usually means the flat at the back with a path down one side, or over a garage at the front if the site is deep enough. Services are the hidden cost: sewer, water and power all have to reach it, and a long run under an existing house adds up. We check the sewer alignment on the first site visit.

The Queenslander alternative

If the main house is a raised Queenslander, the two-bedroom flat you want may already exist as an undercroft. Raising the house and building under gives a self-contained lower level with its own entry, at ceiling heights the flat could not match, without using any more of the garden. It is the Brisbane version of the granny flat and it adds to the value of the house in a way a separate building does not always do. We price both when the house suits it.

What to decide before you start

Who it is for, and for how long. A flat for elderly parents wants a level entry, a wide bathroom and no steps. A flat to rent wants privacy and a separate meter. A flat for adult children wants to be convertible into a home office or a studio later. The plan changes for each, and it is much cheaper to decide at the drawing stage than after the slab is poured.

Bring a copy of your title and a photo of the back yard to a free meeting at the studio. We will tell you whether the block can take a secondary dwelling, and whether the house you already have might be the better answer.