Mould on walls and decorations

Why is my house mouldy?

Picture of Bryan Hindle CSRT CSSW GradIOSH

Bryan Hindle CSRT CSSW GradIOSH

Bryan is Technical Director of Brick-Tie Limited

Why is my house mouldy?

This is a question we get asked almost every day, especially in winter. There was a time when the mouldy house situation was quite rare but over the last decade mould has become the number one complaint in Yorkshire, when clients or landlords call us with a damp problem. It’s always – why is my house mouldy ?

black mould on a shower ceiling why is my house mouldy?
Ugly black mould growing above the shower in this bathroom

So, what has changed? Well two things really:

First – Our houses have been robbed of their fireplaces with most flues and chimneys now bricked up. We’ve also installed double-glazing in much of the housing stock in Yorkshire, which has done away with the drafts from old wooden window frames. This means that older houses, which are modernised, are far less well ventilated than houses back in the day. The result is that the air in houses isn’t changing regularly with fresh air from outside. As a result water vapour levels rise and mould loves this.

Second – Our prosperity since the Second World War, has brought about massive social change. Whereas once we had to heat enough water for a bath or laundry with the fireplace for hours; we have hot water at the flick of a switch now. We never wear clothes more than once before washing them and most people shower or bath every day. This means that we produce vastly more water vapour than say, a family in Leeds, Sheffield or York did, say in 1940 and, they lived in a house of drafts, not one which is sealed up like ours are.

Like it or not this change is permanent and we live in houses which are much more humid than in the past. Some people link the increase in Asthma, skin irritations and many allergies to this social and housing change.

One thing is for certain ?these are the main reasons why mould in houses is now quite common.

mould on decorations in Leeds - why is my house mouldy?
Ruined decorations caused by mould and damp

So can we get rid of mould?

We already have done in hundreds of cases, from Sheffield to Scarborough and Skipton to Leeds. We don’t suggest not washing, bathing or opening up the fireplaces or getting rid of the double-glazing!

The most important thing is to make sure that all the rooms where we produce ‘extra’ water vapour are properly ventilated. These ‘wet rooms’ (bathrooms, kitchens and utilities), need excellent extraction and the Building Regulations stipulate how efficient this should be (Approved document part F – means of ventilation). In addition, it is known that cold houses are damp houses. This is because cold air can hardly carry any water vapour and it becomes near saturated very easily, even if ventilation is adequate. This is cold comfort if you are in fuel poverty, but it is really essential that houses are heated properly. Sometimes owners and tenants will heat the main rooms and, for example leave a spare bedroom unheated to save money. It’s very common to find that this spare room then seems to be damp and may have mould on walls, ceilings or even furnishing and clothes. Keeping the heating on everywhere is best if you can afford to do it.

A good balance of efficient extraction in the wet rooms combined with reasonably warm rooms, is a great way of controlling mould growth because it keeps the conditions too warm and dry for mould to grow.

Another way of helping keep mould down is to avoid making extra water vapour in the dry rooms of the house. This includes avoiding drying clothes on radiators in these rooms or setting up a clotheshorse, to dry things in the lounge, bedrooms or hallway. If radiators must be used for this, then only the radiators in the wet rooms should be used. This enables the extractor fans to get the water vapour out, before it spreads around the colder areas and causes mould growth.

What else can be done to eradicate mould?

Heat is expensive, so insulating walls and ceilings is a good way of saving the heat to keep the surfaces warm. Loft insulation and cavity wall insulation or even internal insulation such as dry-lining can help a lot. Special thermal paints such as SureTherm can make a big difference too. Where solid walls, lacking a cavity are concerned, our Deepshield external water repellent cream is a great option, to help keep walls warmer and reduce the risk of internal mould growth. It also stops water penetrating through the walls in wet weather.

Our surveyors are qualified domestic ventilation engineers as well as damp surveyors. We can not only test for underlying dampness, but also measure and monitor the internal environment, with great accuracy.

water vapour measurment can tell you the answer to why is my house mouldy?
Our surveyors can measure the amount of water vapour in the air with great accuracy – and find out why levels are high

Existing extract fans are checked to Part F of the building regulations using calibrated equipment, so we can see if they are working correctly, properly specified and sufficient. If necessary, we can specify and commission new ventilation equipment, which will meet the Building Regulations and is guaranteed to clear mould problems.

In cases of very heavy mould growth we also offer safe and effective mould sterilisation treatment and anti-mould paints, to clear a problem before any other improvements take effect. We sell and also apply anti-condensation paints.

extract fan testing and commisioning - why is my house mouldy?
To comply with Building Regulations fans should be checked and commissioned – we can do this

The important thing to remember though, is that most mould problems can be treated with relatively little intervention and it is rarely necessary to resort to expensive and disruptive work. This is where a proper survey by our qualified damp and ventilation specialists is necessary. If you have mould or damp problems in your home call us free.

0800 591541

or if a mobile call our office direct from any of the numbers below:

Leeds – 0113 265 2752

York – 01904 566 577

Sheffield – 0114 224 5121

You can book a professional damp survey, using state of the art equipment and by qualified experts for less than you’d think and it may save you money and it will accurately diagnose why your house is mouldy.


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