Do I Need Planning Permission for a Garden Room?
Most UK garden rooms don't need planning permission under permitted development rules. This guide walks you through the exact criteria.
Read Guide →Plan your garden room materials in minutes
Accurate UK-sized material estimates and wall-by-wall breakdowns for DIY garden rooms.
How it works
Enter your dimensions
Input your building's length, width, and wall height. Add doors, windows, and select your roof configuration.
Review calculations
See precise material quantities for every component: timber framing, sheathing, cladding, insulation, and fixings.
Plan with confidence
Use your shopping list and wall-by-wall guides to order materials with confidence.
What you get
Wall-by-wall breakdown
See exactly how many studs, plates, and noggins each wall needs—front, back, left, and right separately.
UK Timber Standards
Calculations follow common UK timber frame construction standards and typical joist spacing assumptions.
Shopping-ready format
Get quantities in purchasable units: linear metres for timber, sheets for boards, square metres for membranes.
Waste factors included
All calculations include appropriate waste allowances (5-10%) for cuts, joins, and installation realities.
Timber optimisation
Quantities account for standard UK stock lengths to minimise waste and help you order efficiently.
Opening framing
Automatic calculations for king studs, jack studs, lintels, and cripples for every door and window you add.
Popular Building Guides
Everything you need to know about planning and building UK garden rooms
How Much Does a Garden Room Really Cost to Build?
Real 2026 costs for DIY garden rooms. What a 3×4m office actually costs (£8,500–£11,000) and where the money goes.
Read Guide →Garden Room Timber Frame Guide
Complete guide to UK timber frame construction. Learn CLS timber sizes, stud spacing (400mm vs 600mm), and wall build-ups.
Read Guide →Built for DIYers
Outbuilding Planner is designed to help UK self-builders plan garden rooms, offices, workshops, and studios. Our calculator uses standard UK timber sizes (47mm CLS) and follows common timber frame construction methods.
Important: These are material estimates only. Always verify your design complies with local Building Regulations, obtain necessary approvals, and consult qualified professionals for structural, electrical, and plumbing work. We assume you have a suitable, level base in place.