When planning a home extension, choosing the right bricks is crucial for both structural integrity and aesthetic appeal. The best bricks for extensions depend on your budget, local building regulations, climate conditions, and the style of your existing home. Engineering bricks offer superior strength and weather resistance, whilst facing bricks provide excellent visual appeal and come in numerous colours and textures to match your property.
Different Types of Bricks for Extensions
Engineering Bricks: The Strongest Choice
Engineering bricks are manufactured to precise specifications with minimal water absorption and exceptional compressive strength. These bricks excel in demanding conditions and are often required for below ground level construction.
Class A Engineering Bricks:
- Compressive strength: Over 125 N/mm²
- Water absorption: Less than 4.5%
- Best for: Foundations, retaining walls, severe exposure areas
- Cost: £0.40-£0.60 per brick
Class B Engineering Bricks:
- Compressive strength: Over 75 N/mm²
- Water absorption: Less than 7%
- Best for: General construction, moderate exposure
- Cost: £0.30-£0.45 per brick
Engineering bricks resist frost damage excellently, making them ideal for the UK’s variable climate. However, their uniform appearance may not suit all architectural styles.
Facing Bricks: Balancing Beauty and Function
Facing bricks are designed primarily for visual appeal whilst maintaining good structural properties. They’re manufactured in countless colours, textures, and finishes to complement different architectural styles.
Common Facing Brick Types:
- Wire-cut bricks: Smooth finish, consistent size
- Handmade bricks: Irregular texture, traditional appearance
- Pressed bricks: Dense structure, sharp edges
- Stock bricks: Traditional London style, weathered appearance
Facing bricks typically cost between £0.25-£1.50 per brick, depending on the manufacturer, finish, and local availability.
Brick Grades and Weather Resistance
Understanding brick grades helps you select materials that will withstand your local conditions for decades.
Frost Resistance Classifications
| Grade | Frost Resistance | Best Use | UK Regions |
|---|---|---|---|
| F0 | Not frost resistant | Internal walls only | All regions |
| F1 | Moderate frost resistance | Sheltered external walls | Southern England |
| F2 | Frost resistant | Most external applications | Most of UK |
Soluble Salt Content
Low (L): Less than 0.17% – Suitable for most applications Normal (N): 0.17-0.5% – General construction use Not specified: Above 0.5% – May cause efflorescence
For UK extensions, choose F2 L grade bricks to ensure long-term durability and minimal maintenance.
Choosing Bricks to Match Your Existing Property
Colour Matching Techniques
Matching new brickwork to existing walls requires careful consideration of several factors:
Age-Related Changes:
- Older bricks develop patina from weathering
- Mortar joints may have discoloured over time
- Pollution can darken brick surfaces
Professional Matching Process:
- Take photos of existing brickwork in different lighting conditions
- Collect loose brick samples if possible
- Visit brick suppliers with samples during daylight hours
- Order test panels before committing to large quantities
Many UK brick manufacturers offer colour-matching services. Ibstock Brick and Hanson provide extensive ranges specifically designed to complement period properties.
Regional Brick Styles
Different UK regions have distinct brick traditions:
London Stock Bricks:
- Yellowish colour from local clay
- Irregular texture
- Perfect for Victorian extensions
Red Midlands Bricks:
- Deep red colour
- Smooth finish
- Common in Birmingham and surrounding areas
Blue Staffordshire Bricks:
- Dark blue-grey colour
- Very dense and durable
- Traditional in industrial areas
Best Bricks for Different Extension Types
Single-Storey Extensions
For single-storey extensions, you have flexibility in brick choice since structural demands are lower.
Recommended Options:
- Class B engineering bricks for foundations
- Quality facing bricks for walls above DPC
- Matching bricks for seamless integration
Key Considerations:
- Thermal performance requirements
- Planning permission conditions
- Budget constraints
Two-Storey Extensions
Two-storey extensions require stronger materials and more careful planning.
Structural Requirements:
- Higher compressive strength needed
- Enhanced weather resistance essential
- Proper thermal bridging prevention
Best Brick Combinations:
- Class A engineering bricks for lower courses
- Class B engineering or premium facing bricks above
- Cavity wall construction with appropriate insulation
Rear Extensions and Conservatory Replacements
Modern rear extensions often feature large glazed areas, requiring careful brick selection for thermal performance.
Considerations:
- Thermal mass benefits of dense bricks
- Colour coordination with existing rear elevation
- Integration with glazing systems
Sustainability and Environmental Impact
Recycled and Reclaimed Bricks
Reclaimed bricks offer environmental benefits and unique character:
Advantages:
- Reduced carbon footprint
- Authentic weathered appearance
- Often matches period properties perfectly
Challenges:
- Variable quality and sizes
- Limited availability
- Higher labour costs for cleaning and preparation
The Green Building Council provides guidance on sustainable building materials and their environmental impact.
Modern Sustainable Options
Contemporary brick manufacturers increasingly focus on sustainability:
Eco-Friendly Features:
- Lower firing temperatures
- Recycled content
- Local sourcing to reduce transport emissions
- Improved thermal performance
Brands like Wienerberger and Forterra offer carbon-neutral brick options that meet modern environmental standards.
Cost Considerations and Budgeting
Brick Pricing Factors
Several factors influence brick costs for extensions:
Material Costs:
- Basic facing bricks: £250-£400 per thousand
- Premium facing bricks: £500-£1,500 per thousand
- Engineering bricks: £300-£600 per thousand
- Reclaimed bricks: £400-£2,000 per thousand
Additional Expenses:
- Delivery charges (typically £50-£150)
- Wastage allowance (5-10%)
- Special requirements (colour matching, small quantities)
Labour and Installation Costs
Professional bricklaying typically costs £150-£200 per square metre, including materials and labour. Complex patterns, curved walls, or difficult access can increase costs significantly.
Cost-Saving Tips:
- Order bricks in standard pack sizes
- Plan delivery timing to avoid storage costs
- Choose locally available bricks
- Consider simpler bond patterns
Installation Best Practices
Foundation and DPC Requirements
Proper foundation work is crucial for long-term success:
Foundation Depth:
- Minimum 450mm below ground level
- Deeper in clay soils or frost-prone areas
- Engineer approval for structural calculations
Damp Proof Course:
- Essential at 150mm above ground level
- Must connect to existing DPC
- Use appropriate DPC materials for brick type
Mortar Selection and Mixing
Mortar choice significantly affects durability and appearance:
Mortar Types:
- M4 mortar (1:0.5:4.5) for most applications
- M2 mortar (1:0.25:3) for high-exposure areas
- Lime-based mortars for heritage properties
Key Principles:
- Mortar should be weaker than bricks
- Consistent mixing for uniform colour
- Weather protection during curing
Cavity Wall Construction
Modern extensions typically use cavity wall construction:
Components:
- Outer leaf (facing bricks)
- Cavity (minimum 50mm)
- Insulation (cavity or external)
- Inner leaf (blockwork)
Thermal Bridging Prevention:
- Use appropriate wall ties
- Maintain cavity integrity
- Install insulation correctly
The NHBC Standards provide detailed guidance on cavity wall construction requirements.
Common Problems and Solutions
Efflorescence Issues
White salt deposits on new brickwork are common but usually temporary:
Causes:
- Natural salts in bricks or mortar
- Moisture allowing salt migration
- Poor weather protection during construction
Solutions:
- Allow natural weathering process
- Gentle brushing when dry
- Avoid chemical treatments initially
Colour Variations
Slight colour variations between brick batches are normal:
Prevention:
- Order sufficient bricks from same batch
- Mix bricks from different packs during laying
- Accept natural variation as character
Thermal Movement
Bricks expand and contract with temperature changes:
Management:
- Include movement joints every 12-15 metres
- Use flexible sealants at junctions
- Allow for differential movement
Quality Control and Standards
British Standards for Bricks
UK brick manufacturing follows strict standards:
BS EN 771-1: Specification for clay masonry units BS 3921: Specification for clay bricks (legacy standard) BS EN 1996: Eurocode 6 for masonry design
Quality Indicators
Look for these quality markers:
Certification:
- CE marking (mandatory)
- Kitemark (optional quality assurance)
- BBA certification for innovative products
Physical Properties:
- Consistent dimensions
- Sound when struck
- No visible cracks or chips
Building Regulations and Planning Permission
Structural Requirements
Building control approval ensures safety and compliance:
Key Areas:
- Foundation design
- Wall thickness and height
- Thermal performance
- Fire resistance
Planning Considerations
Brick choice can affect planning permission:
Important Factors:
- Conservation area requirements
- Neighbour consultation responses
- Local design guidelines
- Heritage property restrictions
The Planning Portal offers comprehensive guidance on planning requirements for extensions.
Future-Proofing Your Extension
Climate Change Adaptation
Consider future climate conditions:
Anticipated Changes:
- Increased rainfall intensity
- More frequent freeze-thaw cycles
- Higher summer temperatures
Adaptive Strategies:
- Choose higher weather resistance grades
- Improve drainage design
- Consider thermal mass benefits
Long-Term Maintenance
Plan for future maintenance requirements:
10-Year Tasks:
- Repointing mortar joints
- Cleaning brick surfaces
- Checking for movement cracks
25-Year Tasks:
- Comprehensive condition survey
- Potential repointing of entire elevation
- Replacement of any failed bricks
Summary and Recommendations
Selecting the best bricks for your extension requires balancing multiple factors: structural requirements, aesthetic preferences, budget constraints, and local conditions. Engineering bricks provide superior durability and weather resistance, making them ideal for foundations and exposed areas. Quality facing bricks offer visual appeal and adequate performance for most applications.
For typical UK extensions, specify F2 L grade bricks with appropriate compressive strength for your structural requirements. Invest in professional colour matching if visual integration with existing work is important. Consider the total cost of ownership, including long-term maintenance requirements.
Work with experienced professionals who understand local conditions and building regulations. Quality brick selection and proper installation will ensure your extension performs well for decades whilst enhancing your property’s value and appearance.
Frequently Asked Questions
What’s the difference between engineering bricks and facing bricks for extensions?
Engineering bricks are manufactured for maximum strength and weather resistance, with precise specifications for compressive strength and water absorption. They’re ideal for foundations and high-exposure areas but have limited aesthetic appeal. Facing bricks prioritise appearance whilst maintaining good structural properties, offering extensive choice in colours, textures, and finishes. Most extensions use engineering bricks below ground level and facing bricks for visible walls.
How do I match new bricks to my existing house walls?
Professional colour matching involves several steps: photograph existing walls in different lighting conditions, collect loose brick samples if available, visit suppliers during daylight hours with samples, and order test panels before purchasing large quantities. Many manufacturers offer colour-matching services. Consider that older bricks develop patina over time, so perfect matches may look wrong initially but weather to match naturally.
Are reclaimed bricks suitable for modern extensions?
Reclaimed bricks can work excellently for extensions, offering environmental benefits and authentic character that perfectly matches period properties. However, they require careful selection for structural adequacy, consistent sizing, and freedom from contaminants. Expect higher costs for sourcing, cleaning, and potential wastage. Ensure reclaimed bricks meet current building standards for your specific application.
What brick grade should I choose for UK weather conditions?
For UK extensions, choose F2 grade bricks (frost resistant) with L designation (low soluble salt content) to ensure long-term durability. F1 grade may suffice in sheltered southern locations, but F2 provides better security against freeze-thaw damage throughout the UK. Avoid F0 grade bricks for any external applications as they lack frost resistance.
How much should I budget for bricks in my extension project?
Brick costs vary significantly: basic facing bricks cost £250-£400 per thousand, premium options £500-£1,500 per thousand, and reclaimed bricks £400-£2,000 per thousand. Add delivery charges (£50-£150), wastage allowance (5-10%), and installation labour (£150-£200 per square metre including materials). A typical single-storey extension might require 2,000-4,000 bricks, making materials costs £500-£6,000 depending on specification.