could be hit with costs of up to £5,000 if they make one mistake. Building experts are urging people to keep an eye out for a problem which impacts 27% of homes across the - mould and dampness.

As reported by , data shows that over 900,000 homes in England suffered from damp and mould in 2023. Repair costs can range from £300 to £5,000 when the issue causes serious structural damage. Giles Fallan, the CEO of Buildsafe, warned that damp and mould can also cause serious health issues to homeowners, including an increased likelihood of respiratory conditions and asthma attacks.

He said: "Dampness and mould don't just attack your property, they also attack your body. The respiratory effects can cause serious illness and, in the most severe cases, death."

Illnesses associated with cold or damp housing cost the NHS around £1.4 billion every year. Meanwhile, wider healthcare costs, which may include the mental health impacts from the strain of discovering damp and mould, push this figure up to £15.4 billion.

Giles said there are seven warning signs for people to look out for. The first is the appearance of mould on walls and ceilings.

He explained: "Black or green patches on walls, particularly in corners or behind furniture, aren't just ugly, they signal serious moisture problems needing immediate attention."

The second sign is peeling wallpaper of flaking paint. This shows that moisture is seeping through the walls. Giles said: "Water trapped behind wallpaper or paint destroys adhesives and causes visible deterioration.

The third warning sign is persistent window condensation as it creates the perfect conditions for mould growth. This can be resolved by using installing proper ventilation systems.

Giles added that musty smells is the fourth warning sign. He said: "That distinctive musty smell comes from mould spores already multiplying inside your walls."

Deteriorating window frames or skirting birds can also indicate damp in your home as wood easily absorbs moisture. Giles suggests a simple thumb-press test to check for softeness.

The sixth sign is cold or damp spots on walls as they indicate insulation failures. The final sign is rising tide marks on walls and is considered the most serious.

Giles said: "Tide marks or white salt deposits on lower walls clearly show rising damp moving upward through your brickwork."