Re-Rendering vs. EWI: What’s the Better Choice?

Spring is just around the corner, bringing longer days and warmer temperatures—making it the perfect time for home improvements. As homeowners look for ways to refresh their properties, many face a common question: should I re-render my property for a fresh new look, or invest in external wall insulation at the same time?

While re-rendering can improve your home’s appearance and protect it from the elements, such as rain, wind, and temperature fluctuations, it doesn’t enhance energy efficiency. External wall insulation not only improves curb appeal but also reduces heat loss, lowers energy bills, and boosts your home’s EPC rating.

So, which option is best for you? In this blog, ‘Re-Rendering vs. EWI: What’s the Better Choice?’, we’ll break down the differences, costs, and benefits of just rendering your home vs. installing external wall insulation to help you make the right choice. Whether you’re upgrading your home’s exterior for aesthetics or long-term energy savings, this blog will provide all the insights you need.

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What is External Rendering?

External rendering involves applying a protective and decorative coating to a property's exterior walls. It is one of the most popular cladding methods for homes, offering both aesthetic appeal and weather resistance. The render layer—typically made from plaster, cement mortar, or modern silicone-based materials—helps to shield walls from rain, wind, and environmental damage while enhancing the property's appearance.

A well-applied render can last 30 years or more, depending on the material used and exposure to the elements. The two main reasons for rendering a home are:

1. Protection – Preventing weather-related wear and water penetration.
2. Aesthetics – Creating a smooth, clean, and modern finish.

Rendering is typically applied in multiple coats using a metal trowel to ensure a durable and even surface.

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The Benefits of External Rendering:

Rendering protects and enhances your property in several ways:

• Waterproofing & Weather Resistance – Shields walls from moisture, preventing damp and mould.
• Covers Imperfections – Hides cracks, stains, and uneven brickwork.
• Boosts Property Value – Enhances curb appeal and makes homes more attractive to buyers.
• Customisable Appearance – Available in a variety of colours and textures to suit any style.

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Drawbacks of House Rendering:

Despite its benefits, rendering has some limitations:

• No Significant Insulation Benefits – Standard rendering does not improve energy efficiency unless combined with insulation.
• High Upfront Cost – Quality rendering can be expensive, especially with specialist finishes.
• Not a Fix for Damp Issues – If walls have underlying damp problems, rendering alone won’t solve them.

External rendering is an effective way to refresh and protect a property, but homeowners should weigh the costs and benefits before deciding. While it enhances appearance and weather resistance, it does not provide insulation benefits unless paired with external wall insulation.

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What is External Wall Insulation?

External Wall Insulation (EWI) is a multi-layer system applied to the exterior of a building to improve thermal efficiency and durability. It typically consists of insulation boards (EPS, mineral wool, or phenolic boards), which are securely fixed to the walls, followed by a reinforcing mesh, a render base, and a final finishing coat.

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The insulation layer acts as a barrier, preventing heat from escaping, which helps to lower heating bills and improve energy efficiency of a property. EWI is particularly beneficial for solid wall properties, which lack cavity walls for internal insulation. It is one of the most effective ways to enhance a home’s thermal performance, significantly improving its EPC rating and increasing property value.

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Benefits of External Wall Insulation

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• Improves Energy Efficiency – Reduces heat loss, lowering energy bills, especially in older homes.
• Protects the Building – Shields walls from weather damage, helping to maintain structural integrity.
• Enhances Comfort – Eliminates cold spots and drafts, ensuring a consistent indoor temperature year-round.
• Increases Property Value – Makes homes more attractive to buyers with both improved efficiency and aesthetics.
• Supports Sustainability – Reduces carbon emissions by improving energy conservation.

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Drawbacks of External Wall Insulation

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• Changes Property Appearance – EWI alters the exterior and may require planning permission for certain homes, such as listed buildings.
• Risk of Cold Bridges – Poorly sealed gaps around windows and doors can reduce insulation effectiveness, therefore expert installation is vital.
• Not Suitable for All Properties – Homes with decorative brickwork or structurally unsound walls may not be ideal for EWI.
• Higher Upfront Cost – Requires a larger initial investment compared to standard rendering.
• Potential Moisture Issues – If improperly installed, EWI can trap moisture, leading to damp problems—making professional installation essential.

EWI is an excellent investment for improving energy efficiency, comfort, and property value, particularly for solid-wall homes. However, homeowners should consider costs, installation requirements, and planning restrictions before proceeding. Expert installation is crucial to avoid moisture problems and ensure long-term effectiveness.

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Re-Render vs. External Wall Insulation: Which is the Better Investment?

If you’re planning to refresh your home’s exterior, this is the perfect time to consider whether standard re-rendering is enough or if adding insulation makes more sense. Here’s how the two options compare:

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How Much Does Re-Rendering Cost?

• Cost: approximately £50-£80 per m²
• Full House Cost: £4,000-£8,000
• Project Duration: Typically 1-2 weeks, depending on property size, render type, and weather conditions.

Re-rendering improves curb appeal and protects your home’s exterior but does not enhance energy efficiency or reduce heating bills.

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How Much Does External Wall Insulation Cost?

• Cost: approximately £100-£150 per m²
• Full House Cost: £8,000-£15,000
• Project Duration: Usually 2-4 weeks, as insulation boards must be fitted before rendering.

EWI offers the same aesthetic benefits as rendering but also improves insulation, cuts heating costs, and boosts your home’s EPC rating—making it a long-term investment rather than just a cosmetic upgrade.

Before starting your project, it’s essential to consult local building control authorities or a qualified professional to ensure compliance with regulations.

Ultimately, the choice between re-rendering and external wall insulation comes down to your priorities. If you're simply looking to refresh your home's exterior, re-rendering is a cost-effective and quick solution. However, if you want to improve both the appearance and energy efficiency of your home while reducing heating costs, investing in EWI is the smarter long-term option.

By carefully weighing the benefits of each approach, you can make the best decision for your home, ensuring durability, efficiency, and lasting value.

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With spring on the way, it's the perfect time for home improvements. Whether you're looking to refresh your home’s exterior or improve energy efficiently, choosing the right solution matters. 

If after reading this blog you are still unsure which option is best for your home, we’re here to help! Based in the Midlands, but serving areas as far as Greater London, PD Rendering have been providing a professional rendering service for more than 15 years. Contact us today for expert advice and a no-obligation consultation.