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Building in Winter

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A question we get asked a lot in January and February is whether it is possible to build a foundation in the cold winter months. The short answer is “yes” we work and create quality foundations year round. But the winter months do come with a special set of challenges for foundation building the first being:

Ground Frost*

Foundations cannot be built on ground that is frozen. Period. Frost occurs when water in the soil freezes expanding by 10% causing everything built on it to shift with it. (After the foundation is backfilled the footings will be below the frost line). Any ground that is not solid bedrock will be susceptible to frost (with clay and silt soils being the most susceptible). For these reasons, it is essential that proper steps be taken to prevent the ground freezing after it has been excavated. The most user friendly way of ensuring this is insulated tarps. Available for sale at a selection of local retailers, these tarps trap ground heat and prevent freezing. They are light and easy to remove and replace. However care should be taken to ensure that they don’t blow away on a windy day. Tarps should be left over the exposed foundation footings (even after backfill) to prevent frost until the house can be closed in and heated.

Frozen Concrete

Another concern clients raise about pouring concrete in winter is the possibility of the concrete freezing. This concern can be well founded . When the water component of concrete freezes before curing is complete it can compromise the finished concrete strength in addition to causing cracking, spalding and flaking. Fortunately pouring in low temperatures becomes possible by heating the concrete and by placing anti-freezing additives and accelerators (contrary to some internet myths these additives do not affect the finished strength of the concrete). In fact because concrete actually cures more slowly in cold temperatures, the finished compressive strength can become greater. Freezing largely only becomes an issue when the concrete surface will be finished (such as on a basement, garage or porch). The finishing process creates a thin polished layer at the surface of the concrete. This polished layer is particularly susceptible to being frozen. It is therefore advisable when pouring these surfaces in the winter, that these areas are well heated* to an air temperature of above 0 C for 7-10 days to prevent freezing.

In short with the proper planning and tools, building a concrete foundation in the winter months is not only do-able but can be a great way of getting a head start on your project for the season.

* Please note that Manotick Concrete considers frost protection and/or heating of a job site to be the responsibility of the client/contractor. Therefore the purchase and placement of insulated tarps or other frost protection (such as heaters) is not the responsibility of Manotick Concrete and is never included in our quotes.