At RHL we are often asked for advice on how to solve condensation and black mould issues. This is a typical example of the type of question we receive:
“Could you please advise on what would be an appropriate solution for the 3 bathrooms detailed below. All of them have ceiling extractors fitted by the builders but all are ineffective and we get black mould on the ceiling and walls within a couple of months of cleaning/decorating.
Main bathroom (bath, shower, sink & toilet) approx 10ft x 8ft with a window.
En-suite bathroom (bath, shower, sink & toilet) approx 9ft 6ins x 10ft 6ins – no window or other ventilation.
En-suite – shower, sink & toilet only approx 10ft 6ins x 3ft 6ins – no window or other ventilation.
The distance from the fan to the external wall is approx 20ft.”
What we would recommend is as follows:
The best practice ventilation solution for each of the three bathrooms is the Dryvent B. The Dryvent B bathroom fan is a high performance, dehumidifying fan designed for particularly demanding condensation control requirements of bathroom environments and it is particularly effective for use in properties suffering from damp conditions and black mould.
The Dryvent B continually extracts on low speed to remove moisture laden air at source before it can condense so an added benefit is that this background level of ventilation also improves the air quality throughout the property.
Condensation control is achieved through the inclusion of an internal, microprocessor driven Autostat unit. When the built-in Autostat detects the humidity level rising above acceptable levels the fan triggers into high speed delivering powerful performance when it is needed most.Some other factors would be worth considering in order to control condensation and mould:
Check the ceiling material and the surface coat. Anaglypta type (embossing around woodchip with epoxy glue ) wallpaper should not be used as this is “food for black mould”. It is important to use specific bathroom paints that have anti-fungicidal properties that are repellent to water vapour. These can be found in any high street DIY store.
The cooler the surface the more it attracts moisture from other areas which then rapidly turns vapour in to condensate as the dew point is reached, and you get condensation and then black mould. So it is important to ensure that the ceilings are well insulated!
Apart from localised ventilation other major sources of moisture need consideration. If you have extractor systems in the kitchen and utility rooms that take the locally produced moisture out of the dwelling then these will need to extract to current building regulation rates and preferably be automatic.