21 Dec 2011

Building in the rain

Posted by bcsands

This summer’s unpredictable weather has caused delays in the construction trade. Rain is a builder’s  enemy – not because builders are wimps who don’t want to get wet at work, but because wet weather can cause potentially serious damage at almost every stage of the building process. Here are some of the reasons why builders down tools when the rain starts coming down.


Rain doesn’t necessarily damage wood – if wood gets wet, it should dry out in a day or two and suffer no lasting damage.  So rain doesn’t usually cause too many delays when a wooden frame is being put up – unless it is extreme. A high wind can be more of a problem.

However, if wood is very wet when it is covered, there is a danger of decay. The framework of a wood-framed house must be dry before insulating and plastering can take place. This can cause delays in periods of unrelenting rain, however, when the weather improves the wood should only need a couple of days to dry out.


Brickies can work through a light shower, but anything heavier than that will stop them. That’s because mortar doesn’t adhere to bricks if it gets too wet. Wet mortar should be covered up during heavy rain – a real downpour might even wash the mortar out of the joints. Wet bricks can’t be laid and so must be covered in wet weather.


The amount of water in a cement mix is a critical element that will affect its final strength. While concrete does need moisture to help the curing (drying/hardening) process, no concreter wants any extra water added to his mix thanks to the rain.

Pouring a concrete slab when rain is forecast is not advisable. If the slab absorbs too much water during curing the end result is a weak surface that may dust and crack. Any flooring that is ultimately applied to the top of the slab may also be damaged by the weak surface below it.


One of the last stages in construction – but another activity best left to a dry day. Obviously painting outside in the pouring rain is not a good idea, but painting inside on a cool, wet day is also not ideal. Oil-based paints can run in cold weather, leaving streaks. Paint needs heat to dry and while heaters and lights can help, a warm day on which you can open windows and doors is better – and also cuts down on fumes, creating a safer environment for the painter.

Fast drying paints like lacquers should never be applied on a wet day –moisture can get trapped in the paint, resulting in blisters and peeling at a later date.


Many landscaping projects also involve some of the construction techniques above, so landscapers run into the same problem as builders in wet weather. Wet grass can’t be cut or edged and heavy rain turns soil into sludge and can drown young plants. No landscaper wants to create a beautiful garden only to see it washed away a few hours later!

So what can builders do in the rain?!

Builders have to take precautions to ensure that heavy rain doesn’t wash earth, gravel and building supplies off their site.  One of the few jobs builders can – and should – do during heavy rain is ensure that their site run off prevention measures are in place. These might include sand bags, silt fence, filter socks, straw bales and purpose-designed devices such as BioSock.

Other than that, there is little a builder can do except get on with paperwork and hope that the rain stops soon!

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