Planning · Yield
Mar 2026
Most clients come to us with a footprint in mind. They've paced the block, sketched a rough outline on the survey, and assumed the only constraint is the setbacks marked on the plan. Then they discover the two invisible numbers that actually decide how much house their lot can carry — site cover and gross floor area. The setbacks tell you where the building can sit. Site cover and GFA tell you how much building you're allowed to put there.
The two numbers
Site cover is the proportion of the lot footprint that's covered by buildings, measured at ground level. Verandahs, balconies, eaves wider than 600 mm, and carports all count. Open landscaped courtyards don't. A typical Low Density Residential lot under Brisbane City Plan 2014 caps site cover at 50% — meaning on a 600 m² block, no more than 300 m² of building footprint.
Gross Floor Area (GFA) is the total floor area of all enclosed spaces in the building, measured to the outside of the external walls. Garages count. Roof-space attics with stairs count. Open verandahs and balconies usually don't. A two-storey house with a 200 m² ground floor and a 150 m² first floor is 350 m² GFA.
The site cover number controls the building's spread; the GFA number (where it applies) controls the building's volume.
What your lot actually allows
Site cover and GFA limits vary by zone and by lot size. The headline numbers for the most common Brisbane residential zones (always check the current City Plan version — these are 2026 indicative):
Low Density Residential (LDR) — small lot (under 450 m²): site cover up to 50%, no formal GFA ratio, but building height capped at 9.5 m / two storeys.
Low Density Residential (LDR) — standard lot (450–800 m²): site cover 50%, height 9.5 m.
Low Density Residential — large lot (over 800 m²): often a 30–40% site cover cap depending on character constraints.
Low–Medium Density Residential (LMR): higher allowable site cover (typically 50–60%), and density unlocks for duplex / dual occupancy / townhouse.
Character Residential zones: often a 40% site cover cap and stricter additional volume controls.
How site cover and setbacks interact
On a small Brisbane lot — say 405 m² with 6 m front setback, 6 m rear setback, and 1.5 m side setbacks — the developable rectangle is roughly 12 m × 14 m = 168 m² before site cover even bites. If site cover is capped at 50% = 202 m², the setbacks have already cost you more area than the site cover cap does. On bigger lots the inverse is true: a 1,000 m² lot has plenty of room between setbacks, and site cover at 50% (500 m²) becomes the real constraint.
The skill is reading both at once. Designers who only think about setbacks miss the GFA tax that an extra hundred square metres of first floor brings; designers who only think about site cover miss the way an extra metre of front setback might let you push a taller form to the rear and pick up volume without violating cover.
The verandah / eave trick
Eaves over 600 mm count toward site cover. Eaves at 600 mm don't. Verandahs and balconies count if they're over a certain depth (typically 1.5 m) or if they're enclosed. On a constrained lot, careful detailing of the eave width and verandah depth can recover 10–20 m² of effective living area without breaching site cover. Done well, it also gives you the deep shading and outdoor connection a Brisbane house wants.
What this means for design briefs
A client says: "we want 350 m² of internal floor area." On a 450 m² lot in LDR, with 50% site cover, the largest possible single-storey footprint is 225 m² — so 350 m² internal needs two storeys plus a garage. On a 700 m² lot, 350 m² over two storeys at 175 m² each is comfortably within cover and you can add a single garage at ground floor while staying under 50%. On a 350 m² Character Residential lot, the same brief might be physically impossible without breaching cover, and the conversation shifts to either a smaller house or a different block.
This is the conversation worth having before the contract is signed on the land, not after. A pre-purchase yield study from a building designer typically costs $400–$900 and can save six-figure mistakes.
The five-year horizon
State and federal housing-supply pressure is pushing in two directions simultaneously: gentle density up (more allowable forms on standard residential blocks — duplex, dual occupancy, secondary dwelling, splitter), and form-quality up (tighter expectations on building character, setbacks, deep planting, soft landscaping). Expect site cover caps to fall slightly in established suburbs (more soft landscaping, more permeable surface, more tree canopy mandated) but yield in other ways to rise (more units per lot, more allowable height in specific corridors).
The lot you bought ten years ago was sized for a single family home. The same lot in 2030 may be allowed to carry a small triplex. The City Plan is mid-trajectory; the smart move is to design with the trajectory in mind.
If you'd like us to run a yield study on a block before you commit to a purchase or a builder's quote, get in touch.
By Ashton Genrich — Building Design — Open, QBCC 15387939