Cement – sometimes a plumber’s best friend!

Published:  14 December, 2015

Dr. Bill Price looks at the advantages of having a little cement in the back of the van

For plumbers, cement isn’t a product that is front of mind when going about their day-to-day jobs.  However it is something that can prove invaluable in certain awkward situations, and knowing which cement to use and how to use it can save a lot of time and hassle.

Plumbers will often need to install or repair pipes or vents that have to pass through an exterior wall. These tend to include waste pipes, water pipes and vents for boilers or tumble dryers.

Why do these projects need cement?  Because they all demand that the gap where the pipe or vent exits the wall is sealed.

This is vital. Without it, the wall will not be weather-tight and this can lead to rain penetrating the indoor space.

Some specialists may opt to use polyurethane foams to seal these gaps. However, this tends to be unsatisfactory. The foam makes neat finishes difficult and, unless it is painted or sealed when hardened, it degrades due to exposure to sunlight, making it a short rather than long-term solution.

Cement based mortars offer a better alternative. They can be pushed into gaps from the outside and then leave a neat, professional finish once they have set and hardened.

As with all cement-based materials however, mortars must be kept moist. This is called ‘curing’ and requires the mortar filling to be covered with a wet cloth or sheet of polythene. There is a risk, if mortar is allowed to dry out too quickly, that it will shrink and leave a gap around the pipe. Always remember that mortar sets by reacting with water, rather than ‘drying out’.

Plumbers don’t need to carry the large amounts of cement needed by builders. Despite this, the majority of bags available are large and require a messy and wasteful process to be usable. Once used, the remaining half-bags are thrown into the back of vans and cover everything in dust – ruining boilers and other plumbing products.

Instead, plumbers may find re-sealable plastic tubs more useful. These allow plumbers to use a small amount of product and then nearly reseal the tub, preventing dust from being spread around the back of a van. Once emptied, these tubs are also great for storage!

Dr. Bill Price is national commercial technical manager at Tarmac Cement