Mould Inhibitor

Weatherproof coatings contain a fungicide to act as a mould inhibitor, to help prevent algae and lichen growing on your roof. However, it is worth bearing in mind that these things seldom grown on the actual fabric and are instead growing on dirt and grit that has built up in the fibres of the roof, so it is important to keep your roof clean.

What it means

A mould inhibitor is a product used to help stop mould coming back after a car has been wet. Once the leak has been found and fixed, and the interior has been stripped, cleaned and dried, a mould inhibitor can be applied to carpets, underlay, seat fabrics and some trims. Its job is to leave behind a residue that discourages mould and mildew spores from taking hold again if there is a little residual moisture or high humidity.

Why it matters

• Helps prevent regrowth: After a leak, mould spores are everywhere in the car. A good inhibitor reduces the chance of new growth appearing on freshly cleaned surfaces.
• Supports odour control: By slowing down or preventing mould returning, inhibitors help keep musty smells from creeping back after a decontamination job.
• Adds a safety margin: In the real world it is hard to get every last nook bone dry immediately. An inhibitor provides some extra protection while any last traces of moisture evaporate.
• Not a substitute for proper repair: Mould inhibitors only work on clean, treated surfaces. If the leak is still active or materials are left wet, mould will eventually win.

Where you’ll see it

You will see mould inhibitor mentioned in leak repair quotes, interior decontamination estimates and flood damage reports. Typical notes include apply mould inhibitor to carpets and underlay, mould inhibitor used after drying or mould inhibitor treatment included as part of decontamination. It may also appear on product labels for interior sanitisers and anti-fungal treatments aimed at damp vehicles.

Context

Mould inhibitor sits alongside leak diagnosis, drying and cleaning in the sequence of putting a wet car right. The proper order is: find and fix the leak, strip out affected trims and soft materials, remove or replace badly soaked soundproofing, dry the vehicle shell and components thoroughly, clean and disinfect, then apply mould inhibitor where appropriate before refitting. On its own, without fixing the leak and drying properly, an inhibitor is little more than a sticking plaster and will not prevent long term mould, rust and electrical problems.

Common mistakes

• Using mould inhibitor as a quick fix without first finding and repairing the actual leak that made the car damp.
• Spraying inhibitor over dirty, still-contaminated surfaces instead of cleaning and drying them properly first.
• Assuming a light mist of product in the air will cure mould inside seats, under carpets or deep in soundproofing.
• Relying on inhibitor alone and skipping proper drying, only to have mould and smells return as soon as conditions are warm and humid again.

Written by Danny Argent. Last updated 04/12/2025 03:37