Summer working tips - Applying render in hot weather

Weber UK

In the UK we often think of weather issues as being something at the other end of the spectrum – too cold, too wet or too windy to work – rarely do we ever highlight the fact that it's too sunny! It’s important to keep an eye on temperatures when working outdoors as keeping yourself and your materials cool is essential on any project.

Hot weather in particular can cause cementitious materials to go off much quicker than usual. Render that stiffens too quickly can become weakened, as the cement has not given time to hydrate fully and reach its full strength.

We've outlined some of the main things to watch out for when applying render in hot weather, as well as some top tips for looking after you and your crew when working in the hotter months:

  • Don't apply above 30 degrees celcius

    Don't apply above 30°C

    Check the temperature of the substrate before applying - not just the air temperature – retained heat will affect freshly-applied mortar.


  • Substrate too hot?

    Substrate too hot? Mist it with water

    Be careful not to saturate the substrate as this can lead to cracking and a poor bond between render and substrate.


  • Always apply render in the shade

    Always apply in the shade

    Follow the sun around the building to avoid applying in direct sunlight


  • Don't let it cure too quickly

    Don't let render cure too quickly

    Hot, windy, or other conditions that can cause faster-than-usual drying conditions mean it may be necessary to mist the render twice daily for three days after applying to avoid it drying too quickly.

To achieve a next-day scrape in warm weather, you will need weber monocouche retarder. It will not damage the colour of your render of your machine as it is a colourless liquid. This product can slow down the scrape time in warmer months if applied correctly, meaning that rendering can still be completed at the standard of 20°C when it is up to 30°C. 

To learn more about using this product effectively, contact our technical team at or call 01525 718877 option 2, or make an appointment with your regional application manager, who can visit you on site to provide a tool box talk on this subject.

Looking after you and your crew

It’s not just materials that need extra attention when it’s warm. It’s important to take care of yourself and your crew when working in hot conditions. Here are our top tips for keeping cool on site:

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    1. Stay hydrated

    In hot weather it’s particularly important to stay hydrated. Consider bringing a fridge on site for the duration of the heatwave and keep it stocked with water. Physically intensive work (like what you’ll be doing on site) in heat will cause you to sweat more than usual, so make sure you’re drinking lots of fluids. It’s best to drink small amounts often so as not to become dehydrated.

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    2. Stay away from caffeine

    As much as we all love our morning coffee, caffeine can be dehydrating, and is best avoided in high temperatures. If you really can’t do without a cup, keep it to a minimum, and make sure you’re drinking enough water to compensate.

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    3. Cross breeze

    If you’re working inside you might be thankful to be out of the direct sunlight, but you could be missing out on the breeze too. Depending on the trades that are working on site, keep doors and windows at opposite sides of the building open to create a nice cross breeze.

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    4. Don't strip off

    While you may be tempted to go for the bare-chested look under your high-vis, it actually won’t make much of a difference in cooling yourself down, and will leave you open to sunburn. Instead go for a loose, light-coloured cotton t-shirt.

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    5. Keep out of the sun

    Where you can, keep to the shade. Take lots of breaks, and make sure people are rotating in and out of the sun.

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    6. Use sun protection

    Protect yourself further from the sun by using and reapplying SPF throughout the day.

The most important thing is to keep yourself cool when working in hot conditions. If you feel lightheaded or dizzy at all, take a break, find some shade, and drink some water.

Keep it cool

We care about building better for people and the planet, so ensuring you look after yourself and those around you during the hotter months is key to producing your best work.

Discover more top tips for rendering in different weather ->

If you're unsure about using our products in hot weather, please feel free to ask us a question – we're always here and happy to help.

Click Compare to help you choose the right product for your project, if you need further assistance please email