Frost Damage / Protection
Although in Britain, it is not unreasonable to expect to work for at least eleven months of the year, during cold weather in particular, care must be taken when working outdoors on paving projects. Whilst it is tempting to work under canvas and portable pop-up tents, which allow for work to proceed even when the temperatures are at or below freezing, it is advisable to avoid working when using any form of cementitious material, or indeed, most ‘building materials’, including resins, grouts, jointing compounds and virtually every other product.
Whilst it is possible to light a fire next to the sand pile to make it ‘workable’ and enable a project to continue, unless the temperatures are three degrees and rising, any work achieved during the day is likely to fail, costing time and money to remove and repeat the operations. Never underestimate the wind chill factor when checking for the likely temperatures forecast for the day, or frost warnings for the following night.
Work should only take place when the temperatures are 3 degrees and rising to 5 degrees.
Frost proofing additives for mortar are available. These tend to be liquid admixtures, designed as accelerants for adding to concrete when working in sub-zero conditions, although they are unsuitable for domestic projects, as they require skill and experience, which may be found on commercial projects where extreme conditions demand solutions.
Whilst these additives are useful for concreting projects, the problems with attempting to carry on working on residential sites on landscaping projects is that the potential for failures extends to the paving materials in use.
A frost proof additive in the mortar will not resolve the problems of slabs frozen together, or covered in frost and invisible ice droplets that will prevent any of the laying materials – laying bed, slurry/bridge bonding compounds from being effective during frost and sub- zero temperatures. As always, carefully read any instructions or advice notes that come with products or materials, as failure to comply with that advice may become an issue in the event of a complaint at a later date.
Failure to protect your work from frost may result in the slabs from becoming loose in their laying bed, especially if the sand and cement has not dried sufficiently to prevent the mix from shrinking and becoming flakey and delaminating from the bonding backed slabs.
The best type of covering to reduce potential frost damage is three or more layers of dry hessian. Wet hessian or plastic sheets are liable to attract even lower temperatures as the moisture and any condensation in or under the sheets becomes frozen.
