Care of extractor fans

Chartered Surveyor James Bush takes a look at extractor fans and what to look out for.  Condensation can be a problem at this type of year as we reduce ventilation rates and turn up the thermostat ...


Condensation can be a problem at this type of year as we reduce ventilation rates and turn up the thermostat.

The use of bathrooms and kitchens together with activities such as drying clothes inside will create large volumes of moist air which will condense on cold surfaces such as windows, wall tiles and particularly in those areas where there is little or no air movement.  It is essential therefore, that in conjunction with improvements to insulation, buildings are properly ventilated.

Automatically operated extractor fans installed into bathrooms and kitchens that operate with the light are essential to perform the task of extracting moisture laden air from such rooms quickly and efficiently.

Approved Document F of the Building Regulations stipulates that a new bathroom should have a fan fitted that extracts at a rate of no less than 15 litres per minute and that runs for a period of at least 15 minutes after the light has been turned off.  Otherwise, it is easy to leave a bath or shower room, turning off the light, that shuts off the fan, leaving warm, moisture laden air in the room to condense as it cools.

Often these fans become blocked by dust etc. so every now and then they ought to be isolated, have their cover removed and be cleaned out. The easiest way to do this is with a vacuum cleaner hose pipe.

It is clearly important to remove that damp laden air to the outside. Some fans exit directly through an external wall; others pass through a roof space to an end termination point. Often these systems are run in plastic flexi-tubes with a metal reinforcement coil. Commonly they are draped through a loft space, are rarely secured and with sagging loops (see photo from a recent survey) that don’t allow damp air to be expelled efficiently.

They can also become damaged when moving about a loft space or detach at their joints.

Additionally, over time, moisture in the tubing causes the reinforcement coil to rust, expand and split the tubing. The first signs of this are often brown spots on the ceiling surface below.

So, pop up into your loft and take a moment to check the tubing if you have such a system. If there are sags and loops endeavor to straighten them out; resecure and check the condition of the coil. Best of all, take time to replace in hard horizontally run plastic to the end termination point to eliminate the risk of the tubing splitting altogether.

If your home is suffering from abnormal condensation and you would like advice from a building surveyor, Woodward Chartered Surveyors offer a specialist service.  Contact our helpful team for a quotation on 01923 920950.

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