# The interior design guide > A definitive knowledge base for interior designers: how space, colour, light, sound, temperature and style work in a home, then the decisions a project runs through, with a Lexicon of terms and answers to common questions. All measurements are metric, temperatures in Celsius. The full text of every page is in [llms-full.txt](https://guide.rayon.design/llms-full.txt). Last updated: 2026-10-20 Terms: © 2026 Rayon. All rights reserved. Read and cite freely, quoting short excerpts with a link to the source page. Copying, scraping or republishing the guide, or using it to build or train a competing product, needs written permission. Full terms: https://guide.rayon.design/about ## Recent updates - 2026-10-20: [Survey](https://guide.rayon.design/knowledge/running-a-project/survey) updated (new page). - 2026-10-19: [Colour and materiality](https://guide.rayon.design/knowledge/foundations/colour-and-materiality) updated. - 2026-10-19: [Representation](https://guide.rayon.design/knowledge/foundations/representation) updated (new page). - 2026-10-19: [Styles](https://guide.rayon.design/knowledge/foundations/styles) updated. - 2026-10-19: [Use](https://guide.rayon.design/knowledge/foundations/use) updated. - 2026-10-19: [Space](https://guide.rayon.design/knowledge/foundations/space) updated. - 2026-10-18: [Light](https://guide.rayon.design/knowledge/foundations/light) updated. - 2026-10-18: [Acoustics](https://guide.rayon.design/knowledge/foundations/acoustics) updated. ## Guides - [Space](https://guide.rayon.design/knowledge/foundations/space): The body as the unit: proportions, positions, clearances and the distances people keep. Markdown: https://guide.rayon.design/knowledge/foundations/space.md - [Colour and materiality](https://guide.rayon.design/knowledge/foundations/colour-and-materiality): Colour theory, an interactive wheel, palettes for real rooms, and how texture changes a colour. Markdown: https://guide.rayon.design/knowledge/foundations/colour-and-materiality.md - [Light](https://guide.rayon.design/knowledge/foundations/light): How light is measured, the sun through a room, six lighting techniques, and light that is comfortable. Markdown: https://guide.rayon.design/knowledge/foundations/light.md - [Acoustics](https://guide.rayon.design/knowledge/foundations/acoustics): How sound travels, why rooms echo, what absorbs it, and how to keep it out of the next room. Markdown: https://guide.rayon.design/knowledge/foundations/acoustics.md - [Temperature](https://guide.rayon.design/knowledge/foundations/temperature): How heat moves, why the same reading can feel warm or cold, and how layout and shading keep a room comfortable. Markdown: https://guide.rayon.design/knowledge/foundations/temperature.md - [Representation](https://guide.rayon.design/knowledge/foundations/representation): How interiors are drawn: plan, section and elevation and their cut, seen and hidden lines, axonometric views, diagrams, perspective and rendering. Markdown: https://guide.rayon.design/knowledge/foundations/representation.md - [Styles](https://guide.rayon.design/knowledge/foundations/styles): Ten ingredients every style is built from, and thirteen historical styles read through them. Markdown: https://guide.rayon.design/knowledge/foundations/styles.md - [Use](https://guide.rayon.design/knowledge/foundations/use): Programs, zoning, adjacency, circulation, connection and adaptability: turning activities into spaces that work. Markdown: https://guide.rayon.design/knowledge/foundations/use.md - [Codes and rules](https://guide.rayon.design/knowledge/foundations/codes-and-rules): Rules and scope, safety, accessibility, comfort and services, and approvals: finding the requirements that apply and carrying them to completion. Markdown: https://guide.rayon.design/knowledge/foundations/codes-and-rules.md - [Survey](https://guide.rayon.design/knowledge/running-a-project/survey): Measuring the existing space by hand, by phone LiDAR or by laser scanner, and redrawing it as a clean CAD plan in Rayon. Markdown: https://guide.rayon.design/knowledge/running-a-project/survey.md ## Chapters - [Foundations](https://guide.rayon.design/knowledge/foundations): Before any decision about walls, sockets or sofas come the principles every room obeys. - [Running a project](https://guide.rayon.design/knowledge/running-a-project): Every project passes through the same stages, whatever its size: taking the brief and surveying the space, defining the need, proposing an idea,… - [Surfaces](https://guide.rayon.design/knowledge/surfaces): Floors, walls and ceilings are the largest areas in any room, and they set its light, colour and sound before a single piece of furniture arrives. - [Space planning](https://guide.rayon.design/knowledge/space-planning): Space planning decides where everything goes and how people move between it. - [Furnishing](https://guide.rayon.design/knowledge/furnishing): Furniture is where a room becomes usable and personal. - [Electricals](https://guide.rayon.design/knowledge/electricals): Every lamp, socket and switch depends on a cable that goes in long before the room is finished. - [Plumbing](https://guide.rayon.design/knowledge/plumbing): Water decides more of a plan than most designers expect: the soil stack fixes where the bathroom can go, and every tap needs supply in and waste out… - [Joinery & millwork](https://guide.rayon.design/knowledge/joinery-millwork): Built-in joinery turns awkward corners into storage and gives a home its finish. - [Openings](https://guide.rayon.design/knowledge/openings): Doors, windows and the openings between rooms shape light, privacy and movement. - [Finishing](https://guide.rayon.design/knowledge/finishing): Finishing is the last layer: art, curtains, lamps, objects and plants. It is the cheapest to change and the first thing people notice. - [Rendering](https://guide.rayon.design/knowledge/rendering): A render shows the client what a room will feel like before it is built. ## Reference - [Lexicon](https://guide.rayon.design/lexicon): 88 interior design terms with short definitions. Each term also has its own page, at https://guide.rayon.design/lexicon/. - [About](https://guide.rayon.design/about): who makes the guide and how it is written. - [Questions](https://guide.rayon.design/faq): common questions on space, colour, light, acoustics, temperature and style, answered. - [Knowledge base](https://guide.rayon.design/knowledge): every chapter, with search. - [MCP server](https://guide.rayon.design/mcp-server): connect an AI assistant to https://guide.rayon.design/mcp to search the guide and read its articles.