Before an architect draws a room, they usually make a few boxes. Not because the boxes are the design, but because the shape answers questions the rooms never will: will the house fit the plot, how much garden does it leave, how tall does it look from the street, and is there an obvious place for the upper floor to sit. Those are massing questions, and they are cheap to answer while the building is still a handful of blocks.
The four words you need
- Footprint: the outline the building covers on the ground, usually measured to the outside face of its walls.
- Height: given in storeys and in metres. Floor to floor is the distance from one floor level to the next; the clear height is what is left inside once the floor's own thickness is taken off.
- Setback: a part of the building pulled back from an edge, such as an upper floor that steps away from the street.
- Void: space taken out of the volume on purpose, such as a courtyard, a recessed corner or a covered porch.
What a simple volume can tell you
Take a small two-storey house: a 9.0 × 8.4 m box, 2.9 m floor to floor. Even as a plain block it already answers useful questions:
- Area. Two storeys of 75.6 m² hold 151.2 m² measured to the outside of the walls.
- Site. The 75.6 m² footprint on a 480 m² plot leaves 404.4 m² unbuilt; you can see where the garden is and how deep it is.
- Height and presence. The top of the volume is 5.6 m above the ground floor. Put the neighbours next to it and you can judge whether it looms.
- Depth. Nowhere inside is more than 4.2 m from an outside wall, which hints at how the rooms will get light.
- Envelope. Its outside walls measure 34.8 m around, about 202 m² of wall over two storeys, a rough early clue to how much there is to build and insulate.
1 · Volume. How big, how tall, where on the site.
2 · Rooms. What goes where, and how big.
3 · Plan. Walls, openings and exact dimensions.
Massing vs floor plan: what each one answers
| Question | Massing model | Floor plan |
|---|---|---|
| Does it fit the plot, and what is left? | Yes, directly | Only once every storey is drawn |
| How tall does it look from the street? | Yes | No; you need an elevation |
| How much area per storey? | Gross area, to the outside face | Net room areas, after walls |
| Does the bedroom fit a double bed with space to walk round? | No | Yes |
| Can you get from the front door to the stair without crossing the kitchen? | No | Yes |
| Where do the windows go? | Roughly, as a pattern on a face | Exactly, sized and placed in each room |
A massing model cannot tell you whether the house works inside. A floor plan cannot easily tell you whether the house sits well on its site. That is why the two are used together, and why a design usually goes back and forth between them a few times.
Should you start with the rooms or the building shape?
Start with whichever is more constrained:
- Shape first when the site sets the limits: a narrow or sloping plot, a street with a strong building line, height-sensitive neighbours, or an extension that has to sit politely next to an existing house.
- Rooms first when the brief sets the limits: a long list of rooms with sizes and relationships on an open site. Space planning is the name for arranging rooms before walls.
Then test one against the other. Put the room list inside the favourite shape; if the rooms do not fit, change the shape before forcing the rooms. The shape comparison method shows that loop on three worked options.
When is the massing model detailed enough?
Move on to floor plans when you can answer these without hesitating:
- How many storeys, and the floor-to-floor height of each.
- The outline of every storey, to within a few hundred millimetres.
- Which parts step back or stay lower, and why.
- What every exposed flat surface becomes: a roof, a terrace or nothing.
- Roughly where the entrance and the stair go.
Adding windows, materials and detail to a massing model before those are settled mostly produces a prettier version of an undecided building.