Choosing the best render for external walls can make or break your property’s weather protection and appearance. The right external wall render will protect your home from moisture, improve insulation, and last for decades with minimal maintenance.
The short answer: Acrylic render offers the best balance of durability, flexibility, and weather resistance for most UK homes, whilst lime render works best for older properties with solid walls.
What is External Wall Render?
External wall render is a protective coating applied to the outside of your property’s walls. It creates a weatherproof barrier whilst improving the building’s thermal performance and appearance.
Modern renders consist of a base coat (scratch coat), optional mesh reinforcement, and a decorative top coat. This system protects the underlying wall structure from rain, wind, and temperature changes.
Types of External Wall Render
Cement-Based Render
Traditional cement render remains popular for its strength and affordability.
Advantages:
- Low cost
- Strong and durable
- Widely available
- Easy to source skilled applicators
Disadvantages:
- Prone to cracking
- Limited flexibility
- Can trap moisture
- Requires regular maintenance
Best for: Budget-conscious projects on newer properties with cavity walls.
Acrylic Render
Polymer-modified acrylic renders offer superior performance compared to traditional cement.
Advantages:
- Excellent flexibility prevents cracking
- Self-cleaning properties
- Wide colour range
- UV resistant
- Quick application
Disadvantages:
- Higher initial cost
- Not suitable for heritage buildings
- Requires specific expertise
Best for: Modern homes, extensions, and properties in exposed locations.
Lime Render
Traditional lime render has been used for centuries and remains ideal for older buildings.
Advantages:
- Breathable – allows moisture to escape
- Self-healing properties
- Compatible with old buildings
- Antimicrobial properties
- Environmentally friendly
Disadvantages:
- Slow curing time
- Weather-dependent application
- Requires skilled craftspeople
- Limited colour options
Best for: Listed buildings, period properties, and solid wall construction.
Silicone Render
Premium silicone renders offer the highest performance but at a premium price.
Advantages:
- Excellent water repellency
- Outstanding flexibility
- Self-cleaning surface
- Exceptional durability
- Fade resistant
Disadvantages:
- Most expensive option
- Specialist application required
- Limited availability of applicators
Best for: High-end properties, commercial buildings, and challenging environments.
Monocouche Render
Single-coat renders that combine base and finish in one application.
Advantages:
- Quick application
- Consistent finish
- Reduced labour costs
- Good colour retention
Disadvantages:
- Less flexible than multi-coat systems
- Can be difficult to repair
- Limited texture options
Best for: New build properties and large-scale projects.
How to Choose the Best Render for Your External Walls
Consider Your Wall Construction
Cavity Walls (Post-1920s) Modern cavity walls work well with most render types. Acrylic or cement-based renders provide good performance.
Solid Walls (Pre-1920s) Older solid walls need breathable renders like lime to prevent moisture problems. The Society for the Protection of Ancient Buildings provides excellent guidance on traditional building materials.
Insulated Systems If you’re adding external wall insulation, you’ll need a compatible render system. Most modern renders work with external wall insulation systems.
Assess Your Local Climate
High Rainfall Areas Choose renders with excellent water resistance like silicone or high-quality acrylic.
Coastal Locations Salt spray demands superior weather resistance. Silicone renders perform best in these conditions.
Freeze-Thaw Cycles Areas with frequent temperature changes need flexible renders that won’t crack. Avoid rigid cement-based options.
Budget Considerations
| Render Type | Cost per m² (Materials) | Labour Cost | Total Cost Range |
|---|---|---|---|
| Cement | £3-5 | £15-25 | £18-30 |
| Acrylic | £8-15 | £20-35 | £28-50 |
| Lime | £5-10 | £25-40 | £30-50 |
| Silicone | £12-20 | £25-40 | £37-60 |
| Monocouche | £6-12 | £18-30 | £24-42 |
Prices vary by region, property size, and complexity
Aesthetic Requirements
Colour Options
- Acrylic: Widest colour range
- Silicone: Good colour stability
- Cement: Limited but can be painted
- Lime: Natural earth tones
Texture Choices
- Smooth: Modern appearance, easier cleaning
- Textured: Traditional look, hides imperfections
- Through-coloured: No painting required
Step-by-Step Guide to Applying External Wall Render
Preparation Phase
- Survey the walls for structural issues, dampness, or defects
- Clean the surface removing dirt, moss, and loose material
- Repair cracks and pointing as needed
- Apply bonding agent if required by manufacturer
- Install beading around openings and corners
Application Process
- Base coat application
- Apply scratch coat 10-15mm thick
- Create key for next coat
- Allow to cure (24-48 hours)
- Reinforcement mesh (if required)
- Embed in base coat whilst wet
- Overlap joints by 100mm minimum
- Top coat application
- Apply finish coat 5-8mm thick
- Work in manageable sections
- Maintain wet edge to avoid joins
- Finishing touches
- Tool joints and edges
- Apply texture if required
- Protect from weather during curing
Curing and Maintenance
Allow minimum 28 days for full cure. Protect from rain, frost, and strong sun during this period. Regular cleaning and inspection will extend render life significantly.
Common Problems and Solutions
Cracking
Causes: Poor application, unsuitable render type, structural movement Solutions: Use flexible renders, proper reinforcement, address underlying issues
Staining
Causes: Algae growth, pollution, water penetration Solutions: Choose self-cleaning renders, improve drainage, regular cleaning
Blown Areas
Causes: Poor adhesion, moisture behind render, freeze-thaw damage Solutions: Proper surface preparation, breathable systems, quality application
Professional vs DIY Application
When to Use Professionals
- Heritage or listed buildings
- Multi-storey properties
- Complex architectural details
- Warranty requirements
- Lack of experience
DIY Considerations
Small, single-storey areas can be suitable for competent DIYers. However, render application requires skill and experience for good results. Poor application often costs more to rectify than professional installation.
The Federation of Master Builders can help you find qualified local contractors.
Long-term Performance and Maintenance
Expected Lifespan
- Cement render: 15-25 years
- Acrylic render: 20-30 years
- Lime render: 50+ years with maintenance
- Silicone render: 25-35 years
Maintenance Requirements
Annual Inspection Check for cracks, staining, or damage. Address minor issues quickly to prevent major problems.
Cleaning Most modern renders benefit from annual cleaning. Use low-pressure washing and appropriate detergents.
Repairs Small cracks can be filled with matching repair compounds. Larger areas may need professional attention.
Environmental Considerations
Sustainability Factors
Lime Render: Most environmentally friendly option. Natural materials, low embodied energy, fully recyclable.
Cement Render: High carbon footprint due to cement production.
Synthetic Renders: Longer lifespan may offset higher embodied energy.
The Building Research Establishment provides environmental impact data for construction materials.
Energy Efficiency
Proper render application can improve thermal performance by eliminating thermal bridges and air leakage. Combined with insulation, this significantly reduces heating costs.
Regional Variations and Building Regulations
Different UK regions have varying exposure conditions and building traditions. Check with your local planning authority regarding:
- Conservation area restrictions
- Listed building requirements
- Permitted development rights
- Building regulation compliance
Cost-Benefit Analysis
Initial Investment vs Long-term Value
Higher-quality renders cost more initially but offer better long-term value through:
- Reduced maintenance requirements
- Extended lifespan
- Better weather protection
- Improved property appearance
Return on Investment
Good quality render typically adds 3-5% to property value whilst providing decades of protection.
Summary
The best render for external walls depends on your specific circumstances:
For modern homes: Acrylic render offers the best balance of performance, cost, and durability.
For older properties: Lime render provides essential breathability and compatibility.
For premium applications: Silicone render delivers maximum performance and longevity.
For budget projects: Quality cement-based render can provide adequate protection when properly applied.
Success depends as much on proper application as material choice. Invest in skilled contractors and follow manufacturer specifications for best results.
Frequently Asked Questions
What is the cheapest external wall render?
Cement-based render is typically the cheapest option at £18-30 per square metre including labour. However, consider long-term costs as cheaper renders may require more frequent maintenance or earlier replacement.
How long does external wall render last?
Lifespan varies by render type: cement render lasts 15-25 years, acrylic 20-30 years, lime render 50+ years with maintenance, and silicone render 25-35 years. Proper application and maintenance significantly affect longevity.
Can I render over existing render?
Yes, in many cases you can render over existing render if it’s sound and well-adhered. The surface must be clean, stable, and properly prepared. Loose or damaged areas must be removed first.
What’s the best render for a Victorian house?
Lime render is typically best for Victorian properties as it’s breathable and compatible with traditional solid wall construction. It prevents moisture problems common with modern renders on old buildings.
Does external wall render need planning permission?
Generally no, as rendering falls under permitted development rights. However, check with your local council if your property is listed or in a conservation area, as restrictions may apply.