A beginner's guide to rendering walls

Refresh your home's exterior with a coat of render. Find out how to render in our easy to follow guide by DIY and renovation expert Michael Holmes

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Changing and improving the exterior of your home is actually one of the most effective ways of adding value to your property, and new rendering is one of the cheapest ways of achieving this. You home’s exterior is the first thing that any visitors or potential buyers might see, so making sure it has got as much kerb appeal as possible is important, especially if the current exterior is in poor condition, or a mixture of different mismatched materials.

Render can be sand and cement or a flexible, breathable polymer modified render for homes with solid walls. It can hide poor-quality or mismatched brickwork on period properties, and create a sleek finish on modern homes. It can come self-coloured or be painted later. Render works well with masonry or timber cladding, to add architectural interest, and can be matched with external insulation to warm up a draughty home.

How much does rendering cost?

External rendering using a sand and cement ‘scratch coat’ and a finer render topcoat, followed by two coats of external masonry paint will cost in the region of £40–£60 per m². Rendering and painting a typical three-bedroom semi-detached house with 80m² of walls would therefore cost £3,200–£4,800.

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For a solid walled house or where the cavity is too narrow to apply sufficient levels of insulation you may wish to take this chance to add insulation. In this case an external wall insulation system is usually a better option than insulating internally as no space or architectural detail is lost within the property.

There are many different external wall insulation systems, but most of them are promoted on a supply and fix basis by specialists, so they’re not available to the DIY market.

Applying external insulation with a render finish typically costs £70–£90 per m². A typical three-bedroom semidetached house would require 80m², so it would cost £5,600–£7,200.

Rendering a 1950s house to give it a new look

This house didn’t fit well with the period properties in its south-west London street. Render, painted cream, was an affordable solution

Which render finish?

Render can be applied to create a smooth, textured or patterned finish, and comes in a wide range of colours. Consider the type of render you use carefully – lime render with a textured or patterned finish will suit old, historic buildings, while new, silicone-based renders that are flexible, breathable, low-maintenance and smooth in their finish will suit contemporary homes. Modern renders are a big improvement on the concrete renders widely used until recently. Prices typically start at just under £60 per square metre.

How to render a wall

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1. Preparing the walls

Before a building is rendered, the walls should be surveyed, with repairs made to structural defects and any movement stabilised, otherwise the render finish is likely to fail. Any new finish is only as good as the wall behind it.

2. External details

External details such as bargeboards will often have to be removed, along with rainwater and soil pipes and other external details such as alarm boxes. Any vents will need to be extended, and sometimes window sills must be extended too. Metal stop and angle beads are then applied around the window and door openings and corners (or the edges of a terraced property) to provide clean edges for the render. The render system can then be applied.

3. Insulation

Where external wall insulation is being applied before the render coat, this is usually in the form of rigid boards or slabs. The type of fixing needs to be selected depending on the type of wall — which is either mechanically fixed or glued to the walls.

4. Creating a foundation

A fabric render mesh is then applied over the insulation, bedded into the first base coat layer of render. This mesh acts as a reinforcement against cracking. This is followed by one or two more thin coats of render, usually a primer and a topcoat.

5. Building up the render

Different proprietary systems are built up of different layers, using various forms of insulation, including expanded polystyrene (EPS), mineral fibre (Rock Fibre) and phenolic foam (more expensive but superior performance). Different types of render are also used with external wall insulation systems, depending on the application and the desired finish, including polymer cement, silicone and acrylic.

6. Render finishes

Thin coat render systems are designed to be self-coloured so that they don’t need painting. As well as a choice of colours, different finishes are also available, from very smooth to textured. If you have chosen rendering that needs painting, make sure you choose a weatherproof external paint.

7. Final finishes

Finally, the external rainwater and soil pipes etc. can be reapplied. You can expect the total process to take around three to four weeks.

Transforming a house by rendering it

Back to Front Exterior Design transformed the exterior with the removal, resizing and addition of windows, and by applying render and new roof tiles

Do you need planning permission to render your home?

Planning permission isn’t usually required to apply render, providing the house isn’t listed or in a conservation area, and permitted development rights haven’t been removed (visit planningportal.co.uk and check with your local authority).

Rendering work on a substantial part of a house must comply with Building Regulations. In an older house it is likely that the walls will have to be insulated. This will mean adding insulation within the cavity or, in the case of solid walls, by applying insulation on the inside or outside face of the external walls. It adds to the cost but reduces fuel bills by up to 40 per cent.

Dos and don’ts of transforming your home’s exterior

DO ensure the changes you make are in keeping with your home’s age and proportions. ‘Rendered walls on period properties can be painted in pastel hues, with architectural features picked out in white,’ says Michael Zucker, a chartered surveyor for estate agents Jeremy Leaf & Co. ‘Pebble-dashed or badly painted walls can be taken back to the brick, clad or rendered. Damaged brickwork can be insulated and rendered.’

DO consider how the changes you’re planning will fit with surrounding properties. ‘In a terraced or semi-detached house, you need to picture how your house relates to its neighbours,’ adds Michael. ‘In a detached house, more radical treatments can be possible – including alteration of windows, a partial render, tile-hanging or cladding. A design consultant or architect will help you maximise its potential.’

DO check with a local estate agent that your plans will improve, rather than detract from, your home’s value.

DON’T miss the opportunity to improve your property’s energy efficiency if you’re  rendering your home.

DON’T forget to keep some of your budget back in case you need to revamp the garden once the makeover is finished.

This house was extended and rendered to transform it

This detached house was transformed by VC Design using Sto render – an insulated panel with the render applied on top. It improved the insulation on the property and its energy efficiency

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