When Damp Turned Out to Be Poor PIV Maintenance

At JDN Property Services, we’re often called out to homes where occupants believe they have a damp problem. This week’s survey was a perfect example of how appearances can be misleading, and how the real issue sometimes lies in ventilation.

The Customer’s Concern

The customer contacted us after noticing mould growth and a musty odour within her property. She was convinced this was a case of damp and wanted a professional inspection carried out.

Our Survey Findings

Using specialist equipment, we quickly established that the relative humidity levels were unusually high, suggesting condensation rather than rising or penetrating damp.

When discussing the issue, the customer pointed out a Positive Input Ventilation (PIV) system that had been installed by her landlord. She explained that it seemed to work when first fitted but now considered it “a lot of rubbish.”

On closer inspection, we removed the PIV cover and found the real culprit...

The filter was heavily clogged with dust and debris, restricting airflow and rendering the unit ineffective.

Understanding Condensation

Condensation occurs when warm, moist air comes into contact with colder surfaces, creating water droplets. Everyday household activities such as cooking, bathing, drying clothes indoors, and even breathing contribute to excess moisture. If this moisture is not ventilated properly, it leads to persistent condensation, mould growth, and that unmistakable musty smell. Over insulated homes can also be a factor.

How PIV Systems Work

A Positive Input Ventilation unit combats condensation by:

Drawing in filtered, fresh air (usually from the loft space or an external grill).

Gently distributing it throughout the property.

Reducing humidity levels and preventing mould growth.

For these systems to remain effective, regular servicing and filter replacement are essential. A clogged filter, as seen in this case, stops airflow and leaves the property unprotected.

The Outcome

We advised the customer that there was no evidence of structural dampness. Instead, the solution was straightforward:

Clean and maintain the PIV system.

Replace the clogged filter.

Continue with regular servicing to ensure optimal performance.

Once serviced, the system will once again provide fresh air circulation and help manage humidity levels throughout the property.

Key Takeaways

Not all mould is caused by damp, condensation is a common culprit.

PIV systems are highly effective when properly maintained.

Landlords and homeowners should schedule routine servicing to prevent blockages and inefficiencies.

Thinking About a PIV System?

At JDN Property Services, we install and maintain PIV units across Central Scotland. If you’re experiencing condensation or mould—or if your existing system looks anything like the one pictured above—now is the time to act.

Contact us today to arrange a survey or discuss installation options.