Floor, wall and ceiling: base and finish
A surface is made of layers. The base is the flat, firm layer under. The finish is the top layer we see and touch.
- Floor: concrete slab, then a levelling layer or plywood base, then a finish such as tiles, wood or vinyl.
- Wall: a frame (brick wall or wooden studs), then a board or plaster base, then a finish such as paint or wallpaper.
- Ceiling: joists fixed overhead, then a ceiling board, then paint. Space above the board can hide pipes and wires.
Why layers? The base makes the surface flat and strong, and the finish makes it look good, easy to clean and safe. If a finish wears out, we can change only the finish.
Openings: doors and windows
An opening is a gap in a wall for people, light or air. A door opening has a frame and a door leaf. A window opening has a frame and glass.
The wall above an opening would fall without help. A lintel is a strong bar over the opening. It carries the weight above and passes it to the wall on both sides.
Openings are placed for light, air flow, privacy and safe exit. A door normally opens in the direction of escape for public rooms.
Stairs
Stairs join two floor levels. Each step has a rise (height) and a tread (the flat part where the foot goes).
Number of steps = total height ÷ rise. Rise = total height ÷ number of steps.
Comfort rule of thumb: 2 × rise + tread should be about 60 to 65 cm. Steps that are too tall tire people; steps that are too low make people trip. A handrail and a non-slip finish prevent falls. Exact limits come from the local building code.
Interior fixtures (joinery)
Joinery means fixtures made of wood or boards and fixed in the building: cupboards, kitchen units, shelves, doors, window frames and skirting boards. They are often made in a workshop in parts, then fitted on site.
Good joinery is measured exactly, fixed to a firm base and finished so it resists water and wear.
Construction management: order of work
Interior jobs must follow a sensible order so one job does not spoil another. The common order is top to bottom and wet to dry: first services (pipes and wires), then ceiling work, then wall base and paint, then floor finish, and last the joinery and clean-up.
A manager also checks quality (is it level and straight?), time (a schedule), cost (a budget) and safety (safe tools, dust and ladders).
Key formulas and definitions
- Rise = total height ÷ number of steps
- Number of steps = total height ÷ rise
- Comfort check: 2 × rise + tread ≈ 60 to 65 cm
- Wall paint area = wall area − opening area
Worked examples
1. A floor-to-floor height is 2.8 m. A stair has 16 steps. Find the rise.
2.8 m = 280 cm. Rise = 280 ÷ 16 = 17.5 cm.
2. A stair has rise 17.5 cm and tread 28 cm. Is it comfortable by the 2R + T rule?
2 × 17.5 + 28 = 35 + 28 = 63 cm. This is between 60 and 65 cm, so it is comfortable.
3. A wall is 5 m wide and 3 m high. It has a door 1 m × 2 m and a window 1.5 m × 1 m. Find the area to paint.
Wall = 5 × 3 = 15 m². Openings = 2 + 1.5 = 3.5 m². Paint area = 15 − 3.5 = 11.5 m².
4. Arrange: floor finish, ceiling paint, pipes and wires, wall paint. Give the best order and a reason.
Pipes and wires, ceiling paint, wall paint, floor finish. Services go inside first. Paint drips and dust fall down, so the floor finish comes last to stay clean.
Common mistakes
- Laying the finish without a flat, dry base. It cracks or comes loose.
- Forgetting the lintel over an opening, so the wall above can crack.
- Making steps all different heights. People trip because they expect equal steps.
- Doing the floor finish first and then ceiling work above it.