Laying paving when it’s frosty
Laying paving slabs in cold weather is every bit as much of a challenge as wet.
Basically, if you don’t have to lay paving when it’s under 3ºC, then don’t. This avoids the possibility of frost damage. You’ll find that most pointing and cement products recommend working at no less than 3 degrees. Experienced builders won’t lay when the temperature is consistently below zero. This is because laying on frozen ground puts slabs at the mercy of the freeze/thaw action, and they’re likely to be dislodged as the ground thaws out and shrinks.
If it’s very cold rather than frozen, and you really can’t wait, then it’s important to take precautions against the effects of frost. The worst case scenario is that the mortar on which the paving is laid fails to “go off” (this means the cement doesn’t cure). To prevent this happening, you need to use a frost-proof mortar. This speeds up the curing process.
It also helps to cover the mortar over in the evenings, before the temperature drops lower, to prevent the frost from getting into it and freezing its moisture content. The cover needs to be reasonably thick and old carpet is ideal.
When it’s this cold, particular care needs to be taken when installing less porous materials, such as slate or granite paving. We often recommend a bond bridge to aid adhesion between the bedding layer and less porous paving, whatever the weather, but it’s particularly important if it’s very cold. Limestone and sandstone paving are generally more porous, so you shouldn’t have to worry about these.
Updated January 2023