When laying concrete flooring in hot temperatures, special care and attention is required to ensure that the concrete reaches full strength and the correct finish.
In the UK, we recommend avoiding pours when the temperature exceeds 25°C, especially if the work is outdoors and exposed to direct sunlight. When concrete gets too hot, it accelerates the curing process and limits the time your team has to place, level, and finish the slab. This often results in lower overall strength and surface cracking.
Concrete undergoes a process known as hydration as it cures, where water and cement chemically react to form crystals around the aggregates. When external temperatures are too high, this reaction speeds up unnaturally - leading to crystals that grow too quickly and never reach full strength.
Weaker concrete floors are not the only concern. Moisture loss is the biggest threat to freshly poured slabs in hot weather. Rapid evaporation at the surface leads to plastic shrinkage, early-age cracking, and reduced long-term durability. Thermal gradients between the hot surface and cooler inner slab can also cause internal stress and cracking.
That’s why hot-weather installation requires trained and experienced concrete contractors - especially for outdoor applications where full sun and wind exposure can severely affect results.
When exposed to direct sun, concrete can reach surface temperatures of 35°C or more - even when the air temperature is lower. Concrete absorbs heat quickly, especially if the surface is dark, surrounded by reflective surfaces, or exposed to wind.
While avoiding high temperatures is ideal, we understand project deadlines can’t always be moved. Below are several steps we take to protect your slab and ensure proper performance even in warm conditions:
1. Use a set retarder in the concrete mix
We work with trusted UK suppliers to ensure our concrete is suitable for summer conditions. A set retarder slows the curing process, reducing the risk of early-age cracking and giving our teams more time to work the surface properly before it sets.
2. Avoid the hottest part of the day
Whenever possible, we avoid pouring concrete between 11 am and 3 pm. We often schedule early morning or evening pours - and for especially sensitive installations, we may even pour overnight when conditions are coolest.
3. Cool the sub-base and prevent moisture loss
We lightly dampen the sub-base before pouring to stop it pulling water from the slab. We also use curing agents or covers immediately after finishing to retain moisture and slow down evaporation at the surface.
Concrete typically reaches around 70% of its strength in 7 days and full design strength in 28 days. In hot weather, while the surface may appear hard quickly, internal strength may suffer if the slab is not properly cured. That’s why using the right process from day one is essential.
We are concrete flooring specialists with extensive experience working in summer conditions. From material selection to curing strategies, we manage every step to ensure your floor performs — even in challenging heat.
We are concrete flooring specialists with experience installing concrete floors in a broad range of conditions, including hotter temperatures. Get in touch today to discuss your project requirements on 01590 676 585.