Rain can make working with concrete really tricky. At National Mini Mix, we know that British weather often surprises us, and sometimes you just can’t avoid working when it’s wet. With over 20 years of experience providing ready mix concrete in your area, we’ve learned a lot about handling all kinds of weather. This guide will help you understand how to pour concrete when rain might be coming, so your concrete projects can still turn out great even when the weather isn’t perfect.
Why Rain and Concrete Don’t Mix Well
Before we talk about what to do, let’s understand why rain and concrete don’t get along:
- Too much water makes weak concrete – Every concrete mix follows strict British Standard rules. When rain adds extra water to the mix, your wet concrete gets much weaker.
- Rain damages the top layer – Raindrops hitting the surface of the concrete can make little holes or rough spots, which ruins the smooth finish you want.
- Takes longer to harden – Concrete needs time to set properly. Rain slows this down, especially in cold weather, meaning you’ll wait longer before it can handle foot traffic.
- Patchy colour – Rain can make concrete dry unevenly, causing the surface of the concrete to look spotty or different colours in different areas.
Check the Weather Forecast
The most important step is to check the weather forecast before you plan to lay concrete. Try to pick a dry day that’s not too hot or cold. Most ready-mix concrete suppliers in Sheffield say you should pour concrete when there’s no rain expected for at least 24 hours.
Before you order, use our concrete calculator to figure out exactly how much ready mix you’ll need. This helps make sure you have the right amount of concrete mix on site when the weather is good.
If you have to pour concrete when rain might be coming, plan ahead with these tips.
Best Practices for Pouring Concrete in the Rain
Before the Rain
- Have covers ready – Keep plastic sheets, tarps, or special concrete blankets nearby. Make sure they’re big enough to cover your whole project.
- Ask for a drier mix – When rain might be coming, ask for concrete with less water in the mix. This way, if rain adds water to your mix concrete, it won’t be too wet.
- Get extra helpers – More people means faster work. With more help, you can finish and cover the concrete quickly if it starts to rain.
- Set up a tent or cover – For small projects, try setting up a tent or shelter over your work area to keep the wet concrete protected.
- Use concrete pumping services – Our concrete pumping services in Sheffield can help you place concrete quickly, so less of your project is exposed to rain.
- Plan where to put control joints – Mark where you’ll need to cut lines (control joints) in the concrete to help prevent random cracking as it dries, which is extra important in bad weather.
During Light Rain
If light rain starts while you’re pouring concrete:
- Keep working but work faster – Light rain probably won’t cause serious damage if you work quickly and compact the concrete properly before covering it.
- Don’t add more water – The rain will already add water to your ready mix, so don’t add extra water to make the concrete easier to spread.
- Use bull floats carefully – Bull floats are tools that help smooth the top of the concrete. Use them to level the surface quickly but don’t overwork it. Too much smoothing can bring extra water to the surface and weaken the concrete.
- Cover finished parts right away – As soon as you finish a section, cover the surface of the concrete with plastic sheeting to protect it from more rain.
During Heavy Rain
If heavy rain starts or is about to start:
- Stop work right away – Heavy rain can seriously damage fresh concrete.
- Cover all fresh concrete – Use plastic sheets or tarps to protect the top.
- Hold down the covers – Put bricks, stones, or boards along the edges of your covers so they don’t blow away.
- Make sure water can drain away – Create paths for rainwater to flow away from your concrete, not toward it.
After the Rain
Once the rain stops:
- Remove puddles – Carefully take off any standing water from the plastic covering, then remove the covering.
- Check the concrete – Look for any damage or spots where rain might have affected the surface.
- Fix small problems – For little imperfections, you might be able to smooth the surface with a trowel if the concrete hasn’t hardened too much.
- Give it extra drying time – Allow more time for the concrete to dry and harden after it’s been exposed to rain.
Special Concrete Types for Rainy Weather
There are special types of concrete that can help when working in rainy weather:
| Type of Concrete | What It Does | Best Used For |
|---|---|---|
| Fast-drying concrete mix | Hardens quickly, less time in the rain | Small projects, fixing things |
| Water-resistant mix concrete | Handles water better, meets British Standard | Outdoor projects |
| Professional concrete with additives | Lasts longer when wet | Places with lots of people walking |
| Special ready mix | Made just for your needs | Big building projects |
| Extra-strong concrete mix | Stays strong even when it gets wet | Important support structures |
For bigger commercial concrete projects in Sheffield, talk to our team about special mixes made for bad weather. Our professional concrete can be made just right for what you need.
What Happens if You Pour Concrete in Heavy Rain
It’s important to know what can go wrong if you pour concrete during heavy rain without protecting it:
- Flaking – The surface of the concrete might start to flake or peel, especially after it freezes and thaws in winter.
- Weakness – The concrete might not be as strong as it should be according to British Standard rules.
- Rough finish – The surface might end up rough or bumpy, which is hard to fix later.
- Slow hardening – It might take much longer before people can walk on it (foot traffic) or before you can build on top of it.
Scientists at the Portland Cement Association found that wet concrete exposed to lots of rain while being poured can lose up to 30% of its strength. That’s why it’s so important to protect concrete from rain when you’re laying concrete in bad weather.
Getting Help from Experts
For important concrete projects, it’s a good idea to hire professionals who know how to work in bad weather. With years of experience in the concrete business, our team at National Mini Mix can help you figure out the best way to handle your project when it might rain.
We know all about providing ready mix concrete for all kinds of projects. We can help you pick the right concrete mix and the best way to get it where you need it. We’ll tell you whether to use concrete pumping services or regular delivery based on your work site and the weather forecast.
The Concrete Society says that for important building work, you should always talk to professionals when pouring concrete in bad weather to make sure it follows British Standard rules.
Frequently Asked Questions
How long after pouring concrete should I worry about rain?
The first 24 hours are the most important. During this time, wet concrete can easily be damaged by rain. After about 2-4 hours, the concrete starts to harden and isn’t as easily damaged, but you should still protect it for the full 24 hours.
Can I lay concrete if it’s going to rain in 12 hours?
Yes, you can pour concrete if rain is coming in 12 hours. The concrete will have started to set by then, so the rain won’t affect it as much. But you should still cover the surface of the concrete with plastic before the rain starts.
Will rain ruin concrete if it’s already started to harden?
Once concrete has been setting for about 4-8 hours, light rain probably won’t cause serious damage. But it can still make the surface look bad. For best results, keep setting concrete protected from any rain for at least 24 hours before allowing foot traffic.
When should I cut control joints in concrete poured in damp weather?
For concrete poured in damp weather, timing the cuts is really important. Usually, cut the control joints when the concrete is hard enough to walk on without leaving footprints, but before random cracks start—usually between 4-12 hours after pouring, depending on temperature and humidity.
Can I add a sealer to protect new concrete from rain?
Sealers are meant to be put on fully hardened concrete, not fresh concrete. Most concrete needs to harden for at least 28 days before you can add a sealer. To protect it while it’s hardening, use plastic sheets or special concrete blankets.
How can I tell if rain has damaged my concrete?
Look for these signs of rain damage:
- A powdery, flaky surface of the concrete
- Patchy colouring or discoloration
- Rough texture where it should be smooth
- Cracks that show up within the first few days
What’s the minimum temperature for pouring concrete in rainy weather?
According to British Standard guidelines, when it’s rainy, the temperature should be at least 5°C and getting warmer. Pouring concrete in cold, rainy weather below 5°C can really slow down the hardening process and make weak concrete.
Conclusion
While it’s always best to pour concrete on dry days, sometimes the UK weather just doesn’t cooperate. By following these tips, you can reduce the problems rain might cause to your concrete projects, whether they’re big commercial jobs or small projects at home.
Remember that for important building work, it’s always best to talk to professionals who have years of experience working with concrete in all types of weather. Contact our team to talk about your concrete needs and get expert advice on working with concrete in rainy weather.
At National Mini Mix, we provide quality ready-mix concrete in Sheffield and nearby areas that meets all British Standard requirements. We also offer concrete pumping services and expert advice to help your project succeed no matter what the weather throws at you.
