Case study: A dormer bungalow in Otley
with mould and condensation

internal loft vent
cavity wall insulation restricting ventilation encourages mould
restricting ventilation encourages mould growth mould across a ceiling
A storm cover can be used on external vents to all but eliminate problem draughts when a house faces the prevailing wind


The problem

Mould was evident along the walls of the living / dining room in this property. We measured Relative humidity levels in this home and found that they were high. Also the house was cold and expensive to heat.

Our assessment

The house was occupied by five people - one adult and four children. With no extract fans in either the kitchen or bathroom, draught proof windows, and a lot of humidity produced by the occupants then condensation and mould is the likely result.

We also noted that the loft insulation was poor and that there was no cavity wall insulation. Insulating a property makes it warmer and less prone to condensation (and cheaper to heat).

Our solution

We ventilated the loft space by installing internal lapvents.

With the loft sufficiently ventilated we installed a positive input ventilation system to bring fresh air into the house and lower the level of humidity,

To address the mould problem in the living / dining room we installed two 'passive' vapour vents. Because one of the vents was on the windy side of the house we installed an external storm cover to prevent draughts.

Finally the cavity walls and loft were insulated – we were able to arrange for this work to be done at no cost under a grant. Insulating the walls has the effect of making them less ‘attractive’ to condensation, and of course helps keep the house warmer.

The result was a house that was fresher, had much lower levels of humidity, was warmer and cheaper to heat.

See our page on solutions for condensation problems for further information.

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cold walls, no ventilation cause damp, condensation and mould