When you are looking at tired or patchy render, a fresh coat of paint can seem like the obvious answer.
It may be the right approach, but I would check the wall before choosing a colour. You need to know what the render is, whether it has been painted before and what condition it is in.
Choosing exterior render paint involves more than finding a shade you like. The paint needs to suit the surface, and any underlying problems need sorting before you start.
Does the render actually need painting?
First, think about what you want to improve. Is the colour uneven, has the finish become dirty or are you looking to change the appearance completely?
If the main problem is dirt or organic growth, suitable cleaning may be enough to improve it. I would assess the surface again once it is clean and dry before deciding whether to paint.
Where the render is sound but needs a decorative refresh, a compatible paint can be an option. However, painting should follow an assessment of the existing finish and the preparation it needs.
What should you check first?
Look over the whole wall, including around windows, doors, gutters and near ground level. Check for loose render, flaking paint, cracks and persistent damp patches.
If something is failing underneath, a new coating will not make it sound. You might improve the appearance temporarily, but the original problem still needs attention.
I would be particularly careful with cracks that keep returning or patches that remain damp. Find out what is causing them before deciding how to repair or coat the surface.
Does the type of render matter?
Yes. Different renders and existing coatings can have different requirements, so I would not assume that one masonry paint suits every wall.
Try to establish which render was used and whether it has already been painted or treated. Original paperwork or information from the installer can help.
If the render forms part of an external wall insulation system, check the system specification before applying another coating. Where you cannot identify the surface, speak to the manufacturer or technical supplier before ordering.
Which exterior render paint should you choose?
Start with the existing surface and what you want the paint to do. A general decorative refresh, uneven colour and hairline cracking are different situations.
Ecorend SP77 Silicone Masonry Paint is a silicone resin-based option designed to provide weather resistance while allowing water vapour to pass through. Ecorend lists several suitable backgrounds, including render and properly bonded existing coatings.
Webersil P Silicone Paint is another option for suitable render and masonry, including refreshing tired façades. Check Weber’s current guidance for the building and system, as it includes restrictions relating to building height and multi-occupancy use.
Baumit Silikon Color is a ready-to-use silicone resin façade paint. As with the other options, check its suitability for the existing render and any previous coating before deciding.
I would not treat these products as interchangeable simply because they are silicone paints. Preparation, application and substrate requirements still need checking for the product you choose.
What if the render colour is uneven?
Where the main issue is colour variation, Ecorend RP77 Equalising Paint is designed to help achieve a more even appearance on suitable render. Ecorend identifies monocouche render as a suitable substrate.
Before using it, establish why the wall looks patchy. Colour variation and persistent damp staining need different attention.
If you are matching an existing finish, check the colour information carefully. Rendit’s SP77 and RP77 product pages include colour-matching notes, particularly relevant when continuing work started with materials from another supplier.
Can paint cover cracks?
Some specialist coatings have crack-bridging properties. Bauer Kapalux Flex Crack Bridging Paint, for example, is an elastic coating designed for suitable surfaces showing hairline cracks, including old render.
That does not mean it is the answer to every cracked wall. The type and extent of the cracking need to fall within the product’s specification.
I would get larger, widening or recurring cracks assessed first. A flexible coating cannot make loose render sound or resolve the cause of movement.
How much preparation is needed?
The surface needs to be sound and free from anything that could affect adhesion. Loose coatings, dirt and organic growth should be dealt with using methods suitable for the existing render.
Check the chosen paint’s instructions for cleaning, repairs and drying requirements. Any repaired areas also need to be ready for coating before you continue.
Primer requirements can vary. One product may need a separate primer, while another may specify a particular first-coat treatment. I would follow the individual instructions rather than use the same preparation for every paint.
When should you paint exterior render?
Check the forecast alongside the manufacturer’s application guidance. You need suitable conditions while painting and during the drying period afterwards.
Rain, frost, high humidity and hot surfaces can all affect when the work should go ahead. Direct sunlight can also be an issue, even when the air temperature seems reasonable.
The limits are not identical across products. I would plan around the paint’s stated temperature, humidity and drying requirements rather than assume a dry afternoon is enough.
Check colours and quantities before ordering
Before placing your order, make sure you know:
- Which paint is suitable for the existing surface
- What preparation or primer is required
- The area you need to cover
- How many coats are specified
- Whether coverage is quoted per coat or for the complete application
- Which colour and finish you want
Texture and absorbency can affect how much paint you use. Check the coverage information for your chosen product and background rather than relying on a general estimate.
Where samples are available, review them before committing to the full order.
Choosing the right products for the job
Painting existing render starts with understanding the wall. Check its condition, identify the existing materials and choose a paint that suits the surface and the result you need.
It is much easier to establish the preparation and coating requirements at the beginning than to put problems right afterwards.
If you are unsure which exterior render paint to choose, speak to us before ordering. Details of the existing render, photographs and an approximate wall area will help us discuss the options with you.
