Types of Render and Maintenance

House and building rendering and how to maintain it

Gleam Team Cleaning Services – 07581 681994 – exterior cleaning specialists in Kent

Rendering is the application of a cement based mix to exterior walls to provide a decorative, attractive and waterproof finish. Depending on personal preference the finished surface can be smooth or textured and additives can be used to determine the colour.

Types of render

Stucco is a term used to describe all types of render but more specifically it refers to lime based mixes. Lime mortar can also be used for rendering and it uses lime in place of cement.


Cement and lime are what’s known as Binding Agents and these are what holds render together and gives it its strength.

Structural Filler is what constitutes the bulk of the mix and sand is most typically used as filler.

Additives such as acrylic, silicon and polymers are added to alter the fundamental characteristics of the mix including its colour and flexibilty.

Water is an essential component of render that creates a workable mix and activates the bindng agent.

Types of Traditional Render

Lime render

Lime render can be applied to a wide range of building materials including timber frames, brick and stone. This makes it particularly suited for use on older buildings. But its versatility means it can also be used on modern buildings and applied to metal and fibre boards, breeze blocks and engineering bricks.

It is extremely flexible and ideally suited to older buildings more prone to movement and a pigment can be added to create a wide range of colours for lime render.

Cleaning lime render

All renders are susceptible to dirt and staining caused by organic materials, traffic pollution and green and black algae. Lime render is very soft and so needs to be treated with great care to avoid damage to the surface. Jet washers can be used but I would not recommend it unless the work is carried out by a competent, experienced professional who knows how to use a pressure washer. Only low pressure water should be used and sprayed in a wide fan pattern to avoid a concentrated jet.

There are various detergents that can be used to help the cleaning process and biocides may be necessary to remove algae and prevent future algae growth. Contact us for a free quote for external lime render cleaning and all other render cleaning services in Kent, London and south east.

Our preferred method for cleaning walls, brickwork, cladding and render is a low pressure soft wash which is a gentle but effective cleaning solution on fragile external surfaces.

Sand and cement render

This is made using Portland Cement and as a result is significantly stronger than lime render. It is usually finished with a coat of paint to provide protection and a more visually attractive finish. Being so much harder than lime render it is more likely to crack and is only suitable for use on fewer types of building , e.g. new builds that are less likely to suffer from movement.

Again, Gleam Team’s preferred cleaning method would be soft washing with suitable detergents for general staining and biocide for algae removal. Pressure washing is an option but it should it always be borne in mind that all exterior house and building cleaning should be done using the minimum amount of water at the lowest possible pressure.

Exterior walls should not be unnecessarily saturated and water should never be blasted with such force it penetrates into wall cavity.

Pebble dash

Pebble dash refers to a decorative finish in which pebbles, gravel or shale are coated with wet mortar. It is also sometimes called roughcast and is often found on external walls of houses in the UK built in the 1920s and 1930s. It can be found on both lime and cement based renders.

Modern renders do not use pebbles at all and in their place are small flint chips known as spar. Varieties still in use include Canterbury Spar and Yellow Spar.

Pebble dash cleaning

Particular care should be used when cleaning pebbledash to avoid dislodging the pebbles or flints and we would always recommend softwashing pebble dash. Gleam Team clean pebble dash walls in Kent, London and the south east using specialised detergents applied at very low pressure. They are then gently brushed, rinsed and the process repeated.

Modern Renders

Silicone Render

This is a long lasting render that is flexible, durable and allows the building to breathe. They can be pre-coloured in a wide range of colour options and are usually through-coloured meaning they do not need painting.

Acrylic Render

A cement based render with plastics added to make it more durable and flexible with improved water repellancy.

Polymer Render

Cement based render with polymers added for better resistance to water and flexibilty. Polymer renders usually need painting and tend to be easier to clean and maintain.

Monocouche Render

Monocouche is a French word meaning one coat and it is a cement based render with silicone added and applied with one thick coat using white Portland cement. The use of white cement means colour can be added making it a through-coloured render with excellent water repellancy.

Render Staining

Any type of render will need cleaning to remove black stains caused by pollution and carbon monoxide. If these stains are left on porous render they will absorb deeper into the surface and affect the breathability of render. This can lead to cracks and damage to the exterior of your house and they need to be professionally cleaned to enhance appearance and prevent damage.

Rust stains on rendered walls

Rust staining usually occurs when water and oxygen come into contact with metal containing iron particles. This causes the metal to oxidise and rain drops that come into contact with it then drip down the wall leaving a trail of reddish rust stains on the render.

Rust stains do not affect the structural properties of render but are extremely unattractive and impact the look of a home or commercial building. It is possible to remove rust stains from render with the careful application of specialist cleaning products. You can find information online suggesting the use of various household products for rust removal such as baking soda, vinegar and lemon juice but I would definitely NOT recommend such DIY methods that are likely to do more harm than good.

Contact Gleam Team Cleaning Services for rust removal, render cleaning and wall and brick cleaning in Kent, London, Surrey and East Sussex.

K Rend

K Rend is a cement based coloured silicone render for external walls of residential homes and buldings. K Rend is the largest manufacturer of silicone coloured render in the UK. Their products provide a highly attractive, smart, water repellant finish to buildings and are available in an extensive range of colours.

K Rend cleaning

K Rend themselves advise cleaning render on an annual basis with detergent and a gentle jet washing. They recommend treating algae with a biocide or algaecide. They also sell an own brand product for this – K Rend Algae Clean.

Weber Render

Weber manufacture a range of coloured render and decorative finishes including smooth and textured. They produce monocouche render, a French word meaning ‘single coat’, in a variety of colours for a weather proof and attractive finish residential and commercial properties.

Weber Render cleaning and maintenance

Weber also recommend cleaning their render using a low pressure jet wash and detergent and this must be done with great care. Render should never be blasted with high pressure water as this will damage it or cause striping marks.

They also manufacture a protective coating called Weberend Protect which repels water and protects render against water, oil and grafitti.

Render cleaning services in Kent, London & the South East

Gleam Team provide professional render cleaning in Kent, London, Surrey and Sussex. We combine low pressure soft washing with occasional pressure washing, if necessary and only on suitable renders, for the most effective and comprehensive render cleaning service in the south east.

Cleaning algae from render

Green, red and black algae can be cleaned and completely removed from render by the professional grade specialist biocide we use. It also has a residual ongoing benefit and continues keeping rendered walls free of algae by killing biological spores that may come in contact with the wall. North facing walls are most susceptible to algae as it prefers damp areas where if left untouched algae will thrive and colonise the entire wall.

Both K-Rend and Weber Render recommend using a suitable biocide or algaecide. Gleam Team use Bio Cleanze biodegradeable softwashing biocide for the removal and prevention of green, red, yellow and black algae, lichen, moss and other bio;ogical spores. Bio Cleanze keeps on working for 12 months or more after application.


We are also able to remove white salts known as efflorescence that can appear on all types of render. Ths is a highly specialised task that needs specific chemicals and knowledge and experience of how to use them.

Protective Treatments for K-Rend & Weber Render

Just like any other bulding facade, all types of render are susceptible to staining caused by organic growths, traffic pollution and grafitti and will need cleaning to keep them looking their best. In addition K-Rend and Weber produce water repellant protective treatments.

K Pro

This is a water based product manufactured by K Rend. It is described as :

protective treatment used to provide long term, enhanced water repellent properties to external render and other masonry surfaces.

source K Rend Homeowners Guide pdf

It has enhanced water repellancy and prevents water intrusion keeping the substrate clean and dry for longer.

Weberend Protect

Made by Weber this is another water repellant protectve coating for monocouche render, and also prevents the build-up of dirt and protects against UV fading, oil and grafitti.

Gleam Team are able to apply these treatments to your render as part of our render cleaning service and exterior house and building cleaning services in Kent and the home counties.

Soft washing – safe cleaning for all types of render

Geam Team are experienced exterior cleaners and are able to clean all outdoor areas and hard surfaces. We also understand that best practice always recommends using the minimum amount of water and water pressure to safely clean fragile surfaces such as render, brick and cladding. Soft washing is the low pressure application of specialist cleaning products designed for powerful outdoor cleaning.

The very low pressure of water flow is completely safe as are the detergents that are applied when used according to the manufacturers instructions. Soft washing was originally developed in America for cleaning delicate external surfaces such as roofs and the process and cleaning products used have been continually developed and improved since soft washing came to the UK. There are a number of manufacturers in the UK and Ireland who specialise in the development and efficacy of these cleaning products. The products we use are fully approved by the UK Health and Safety Executive.

We provide render, wall and brick cleaning in the following areas :

  • Maidstone
  • Medway Towns
  • Gillingham
  • Rochester
  • Strood
  • Ashford
  • Canterbury
  • Swale
  • Tonbridge
  • Sevenoaks
  • Tunbridge Wells
  • Kings Hill
  • East & West Maling
  • Gravesend
  • Bexleyheath
  • Sidcup
  • Bromley
  • across south London
  • Surrey
  • Sussex
  • Essex

Please call 07581 681994 or email using Contact Us for further information or to arrange a free quote.

Our other exteror cleanng solutions in Kent and London

We are able to clean all external areas and hard surfaces around houses, gardens and commercial premises throughout Kent and London. One area we specialise in and have a great deal of experience in it is block paving renovation and refurbishment and patio and driveway cleaning and sealing .

To the left are a few examples of our work to demonstrate the level of expertise. 2 of the photos show an Indian Sandstone before and after cleanng by us and the 3rd image is an example of block paver refurbishment, cleaning, resanding and sealing.

Using a variety of cleaning methods after considering which is the most suitable for any given surface, we are able to provide professional cleaning in Kent and London of :

  • roof moss removal and roof tile cleaning
  • wall and brick cleaning including after builders clean up for new builds
  • fascias, soffits and gutters
  • UPVC and timber cladding
  • pressure washing services
  • decking cleaning, maintenance and staining / oiling.

Please feel free to get in touch with us for a free, no obligation quote or for any other queries you may have.

Other blog posts that may be of interest include the driveway and patio cleaning and sealing hub, FAQs page and roof cleaning information and prices.

Sources and References :

Designing Buildings (October 2020) – Rendering – available at https://www.designingbuildings.co.uk/wiki/Rendering

UK Weber (June 2021) – Render Ceaning – avaiable at https://www.uk.weber/blog/helpful-advice/render-cleaning

K Rend (2021) – Homeowners Gude – available at https://www.k-rend.co.uk/pdf/Homeowners_Guide.pdf

Share this post