Free Construction Compliance Tools
Part A, Part L, Foundations, Fire Resistance & More
Welcome to our comprehensive collection of UK Building Regulations calculators designed for builders, architects, structural engineers, and DIY enthusiasts. Our free tools help you calculate requirements for Building Regulations compliance across foundations, structural elements, insulation, fire safety, and damp protection.
All calculators are updated for 2026 UK Building Regulations including Approved Documents Part A (Structure), Part L (Conservation of Fuel and Power), Part C (Site Preparation and Resistance to Contaminants and Moisture), and Part B (Fire Safety). Get instant results for foundation depths, DPC heights, U-values, fire resistance periods, and structural loads.
Calculate foundation depths, widths, and strip foundation requirements for Building Regulations compliance
Calculate minimum foundation depth based on soil type, building load, and frost protection requirements. Compliant with Building Regulations Part A.
Determine required strip foundation width based on wall loads, soil bearing capacity, and Building Regulations requirements.
Complete strip foundation calculator including depth, width, concrete volume, and reinforcement requirements for domestic buildings.
Calculate structural loads and verify compliance with Building Regulations Part A (Structure)
Calculate dead loads, live loads, and total structural loads for domestic buildings. Includes floor, roof, and wall loading calculations.
Comprehensive Building Regulations Part A compliance calculator covering structural requirements, wall thickness, and load-bearing capacity.
Calculate U-values and thermal performance for Building Regulations Part L compliance
Calculate U-values for walls, floors, and roofs. Determine insulation thickness required to meet Building Regulations Part L 2026 standards.
Comprehensive Part L compliance calculator for conservation of fuel and power. Calculate insulation requirements for new builds and extensions.
Calculate DPC heights and DPM thickness for Building Regulations Part C compliance
Calculate required damp proof course (DPC) height above ground level. Ensures compliance with Building Regulations Part C for moisture protection.
Determine correct damp proof membrane (DPM) thickness for concrete slabs and floors based on ground conditions and Building Regulations.
Calculate fire resistance requirements for Building Regulations Part B compliance
The UK Building Regulations set minimum standards for design, construction, and alterations to buildings. Compliance is mandatory for most building work, enforced through Building Control approval. Our calculators help you meet these requirements across key regulatory areas.
Requirements: Buildings must be structurally stable and safely constructed
Covers: Foundations, walls, floors, roofs, structural loading
Key Standards: BS EN 1990-1999 (Eurocodes)
Calculators: Foundation depth/width, structural loads, Part A compliance
Requirements: Buildings must provide adequate fire protection and means of escape
Covers: Fire resistance, escape routes, fire spread, access for fire service
Key Standards: BS 9999, BS 476
Calculators: Fire resistance periods for structural elements
Requirements: Protection against moisture, contaminants, and ground instability
Covers: DPC, DPM, radon protection, subsoil drainage
Key Standards: BS 8102, BS 8103
Calculators: DPC height, DPM thickness requirements
Requirements: Buildings must be energy efficient and limit CO2 emissions
Covers: Insulation, U-values, air tightness, heating systems
Key Standards: SAP methodology, BS EN ISO 6946
Calculators: U-value calculator, Part L insulation requirements
Building Regulations are organized into Approved Documents lettered A through R. Each document provides practical guidance on compliance with specific regulations. Our calculators focus on the most commonly required calculations for residential and light commercial construction.
📋 Key Approved Documents for Construction:
Most building work requires Building Regulations approval before starting. Understanding when approval is needed helps you plan projects correctly and avoid enforcement action or problems when selling property.
✅ Building Work Requiring Approval:
⚠️ Exempt Building Work (No Approval Needed):
Building Regulations approval can be obtained through your Local Authority Building Control or an Approved Inspector. Both routes provide the same legal compliance but differ in service approach and fees.
Best for: Complex projects, new builds, commercial work
Process: Submit detailed drawings and calculations before starting
Timeline: 5 weeks for approval (8 weeks if extended)
Advantages: Approval confirmed in writing before work starts, formal rejection if non-compliant
Cost: £600-£2,500+ depending on project size
Best for: Simple projects, small extensions, straightforward work
Process: Give notice before starting, submit details as work progresses
Timeline: Can start 48 hours after notice (for most work)
Advantages: Faster start, flexible for design changes during construction
Cost: Similar fees to Full Plans but no refund if work doesn't proceed
Purpose: Obtain approval for work completed without Building Regulations consent
When needed: Buying property with unauthorized work, preparing for sale
Challenges: May require opening up work, difficult to prove compliance retrospectively
Cost: Typically 150-200% of standard fees due to additional inspection burden
Alternative to: Local Authority Building Control
Advantages: Often more flexible, may offer better customer service, can work across LA boundaries
Process: Submit Initial Notice before starting, inspector visits at agreed stages
Cost: Competitive with LA fees, often package pricing available
Foundation design must comply with Building Regulations Part A to ensure adequate structural stability. Requirements vary based on soil conditions, building loads, and proximity to trees, drainage, and boundaries.
Good bearing soil (rock, gravel): 450mm minimum depth
Clay soil: 900-1000mm (seasonal movement consideration)
Near trees: Depth equal to tree height at maturity or engineer's design
Frost protection: Minimum 450mm below ground level
Sloping sites: Additional depth on downslope side
Calculation basis: Wall load ÷ soil bearing capacity
Rock (600+ kN/m²): 400-500mm typical width
Gravel/sand (100-200 kN/m²): 600-850mm typical width
Clay (75-100 kN/m²): 850-1000mm typical width
Weak soil (<75 kN/m²): Engineered solution required
Standard specification: C20/25 grade concrete (ST3)
Sulphate protection: May require C30/37 or sulphate-resisting cement
Minimum thickness: 200mm for strip foundations
Reinforcement: Not typically required for standard strip foundations
Coverage: Min 75mm concrete cover to reinforcement
Trench fill: Narrow trench filled with concrete to within 150mm of ground level
Pad foundations: For individual column loads
Raft foundations: Weak or variable ground conditions
Piled foundations: Very poor ground or high water table
Engineer required: Anything beyond standard strip foundations
Building Regulations Part L sets maximum U-value requirements for thermal elements. The 2021 amendments (updated for 2026) increased insulation standards significantly to meet the Future Homes Standard.
Walls: 0.18 W/m²K maximum
Floors: 0.13 W/m²K maximum
Roofs: 0.11 W/m²K maximum
Windows/doors: 1.2 W/m²K maximum (whole unit)
Party walls: 0.0 W/m²K (full cavity fill or equivalent)
Walls: 0.28 W/m²K maximum
Floors: 0.22 W/m²K maximum
Roofs: 0.16 W/m²K maximum
Windows: 1.6 W/m²K maximum (whole unit)
Note: More relaxed than new builds but still require high performance
Cavity wall (full fill): 100-150mm cavity insulation
Solid wall (external): 100-120mm EPS/PIR boards
Ground floor: 100-150mm rigid insulation under slab
Pitched roof: 270mm mineral wool between/over rafters
Flat roof: 150-200mm PIR boards
Air permeability: Max 8 m³/h/m² @ 50Pa for new dwellings
Thermal bridging: Accredited construction details or PSI-value calculations
Primary heating: Restrictions on fossil fuel systems from 2025
SAP calculation: Required for new builds and some extensions
Building Regulations Part B specifies minimum fire resistance periods for structural elements and compartment boundaries. Requirements increase with building height and purpose group.
🔥 Standard Fire Resistance Periods:
Building Regulations Part C requires effective protection against moisture from the ground. DPC (damp proof course) and DPM (damp proof membrane) are mandatory for most construction.
Minimum height: 150mm above finished ground level (external)
Material: Two-course slate, bitumen felt, polythene, or proprietary DPC
Cavity trays: Required at openings, roof abutments, and cavity closures
Continuity: Must link to DPM in floor to create continuous barrier
Minimum thickness: 300 microns (1200 gauge) polythene or equivalent
Positioning: Below concrete slab or between slab and screed
Laps: Minimum 150mm overlap, sealed or taped
Protection: Sand blinding under membrane to prevent puncture
⚠️ Common Building Regulations Issues:
Our calculators provide quick compliance checks and preliminary calculations for common building regulation requirements. While they're based on approved standards and typical scenarios, always verify results with your Building Control officer or structural engineer for your specific project.
✅ Calculator Best Practices: