- Recent drops in temperature.
Frosty weather and cold periods can bring cold air with very high humidity. As soon as this enters the roof space and comes into contact with any cold service, condensation is formed.
- Breathable membrane not performing correctly
The last 15 years has seen a huge increase in the use of vapour permeable underlay known as breathable membranes. Many have been sold as negating the need for ventilation units to introduce airflow into the roof space, allowing the removal of damaging condensation. The effectiveness of the breathable membrane depends on a number of design considerations, not all of which, if any, would have been met. With ever increasing insulation requirements and winters appearing to be becoming colder again, the incidence of condensation within domestic roof spaces is on the rise.
- Too much or increased loft insulation.
When you add insulation above the top-floor ceilings, you are not actually insulating the loft – you are insulating the top-floor rooms. But this comes at a cost – it makes the roof space cooler. Now, condensation occurs when moisture-laden air hits cool surfaces, so you might well expect to see a bit more condensation on the sarking felt.
Following loft insulation, the air in the rooms below becomes warmer, This means it can hold more moisture, absorbed from the normal human activities of cooking, showering, breathing and perspiring. This warm, moisture-bearing air then passes through the top-floor ceilings into the cool loft.
Why you must act immediately
If condensation problems are allowed to escalate it can become an extremely costly problem, so it’s important to catch it early and attend to it immediately. Water can lead to mold, wet insulation, and roof failure. Check your roof space regularly and make sure you keep a roof system historical file to stay on top of the situation.