The interior design guide

Open Rayon

All sections

Knowledge

2Running a project

Survey
Programming
Concept design
Design development
Pricing
Documentation
Supervision

Flooring by room
Colour: undertone, LRV, light
Paint sheen by surface
Stone and tile
Joinery materials
Junctions and transitions

4Space planning

Zoning an open plan
Circulation and clearances
Furniture layouts that work
Doors, swings and openings
Testing a plan at 1:50
Planning a small flat

Sofa scale and depth
Rug sizing
Dining table and pendant
Beds and bedsides
Vintage, new or custom
Reusing what the client owns

The socket plan
Switches, circuits and scenes
Ceiling spots: grid or wall wash
Floor sockets for floating furniture
Kitchen and bathroom circuits
Data, TV and charging points

Where the soil stack sets the plan
Supply, waste and fall
Kitchen sink and appliances
Bathroom layout around the WC
Showers: valves, trays and wet rooms
Heating: radiators or underfloor

8Joinery & millwork

Kitchen carcasses and fronts
Wardrobes and alcove storage
Shelving that doesn’t sag
Skirtings, architraves and panelling
Doors, hinges and handles
Drawing joinery for the maker

Door schedules: sizes, swings and hardware
Window schedules: glazing, sills and heads
Openings without doors
Ironmongery and handles
Thresholds and level access
Fire, acoustic and privacy ratings

Art: size, height, grouping
Curtains: height, width, fullness
Lamps as objects
Shelves and objects
Plants
Knowing when to stop

Materials and finishes for a render
Daylight, evening and artificial light
Ambient occlusion and contact shadows
Camera height and lens
Styling a render
From render to client sign-off

Others

Lexicon FAQ MCP About

Fall.

What it means in interior design.

Fall is the slope a waste pipe needs so water drains by gravity, written as a ratio or millimetres per metre. Without enough fall, pipes block and smell.

In practice

Small waste pipes need roughly 1:40 to 1:80 (rule of thumb), so a basin 3 m from the stack drops several centimetres along the run. That depth has to fit in the floor or behind boxing, which is why remote sinks raise floors.

Where the guide uses it

Defined here, in the Lexicon.

Related terms.

More from Plumbing.

Soil stack

The soil stack is the vertical pipe that carries waste from WCs and sinks down to the drain, and vents the system above the roof. Every WC needs a short, falling route to it.

Thermostatic valve

A thermostatic valve mixes hot and cold to a set temperature and holds it when pressure changes elsewhere in the house. It stops a shower scalding when someone runs a tap.

Wet room

A wet room is a bathroom where the shower floor is level with the rest and the whole room is waterproofed (tanked) and drains to a floor gully. There is no tray and often no screen.

Underfloor heating

Underfloor heating runs warm-water pipes or electric mats under the floor finish, so the whole floor becomes a low-temperature radiator. It frees the walls of radiators.

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