Download As PDF

As I wrote in January 2023. Lastingly high energy prices have created the perfect conditions for the rise of a particular blight across the country. 

Surveyors have reported a tenfold increase in calls from worried landlords and homeowners. These landlords and homeowners have discovered damp and mould hiding in their properties. This issue threatens to cause chaos.

New-build homes in the UK must last 60 years, but without mechanical ventilation, they may not last that long.

This standard, rooted in old mortgage provider requirements based on two typical mortgage terms, is becoming outdated. Concerns are growing as building materials and methods evolve to meet net-zero targets. This minimal lifespan is no longer good enough. It does not protect homeowners from future costs and failures.

Experts are increasingly critical of the situation. Freya Chapman from the ground engineering firm Mainmark has described it as an outrage that modern construction, with all the advantages of advanced engineering, still produces homes that may not last. She argues that stronger guarantees are essential and that legislation is urgently needed to ensure the durability and sustainability of new homes. Without such protections, repair costs will inevitably climb as these buildings fail in the coming decades.

Alongside structural concerns, the conditions inside many new homes are also deteriorating. Soaring energy prices have intensified problems that were already widespread. Surveyors report dramatic increases in damp and mould. Properties of all ages are affected, from Victorian terraces to homes built as recently as the mid-20th century.

The problem has taken on a modern twist in new builds. High levels of insulation and airtight construction, paired with inadequate ventilation, allow moisture to build up inside. The result is condensation, damp patches, and mold growth. These issues pose serious risks to both buildings and the health of those living in them.

Many occupants of new-build homes now report persistent mold problems. The cause lies in the very design features that are marketed as sustainable.

Homes are built to be airtight to conserve heat and reduce energy use. However, without continuous and adequate ventilation, moisture from daily life has nowhere to go.

In older houses, natural draughts and breathable materials provided some relief. Water vapour lingers in today’s sealed environments, settling on cold surfaces and allowing mold to thrive.

Air-source heat pumps, widely promoted as the future of home heating, add another layer to the problem. While these systems work efficiently in airtight, well-insulated buildings, they do nothing to remove stale air or reduce humidity. Heat pumps move heat but don’t manage air quality.

Moisture accumulates without a dedicated ventilation system like Mechanical Ventilation with Heat Recovery (MVHR). This is often overlooked as developers focus on energy ratings and insulation while treating ventilation as an afterthought. Basic extractor fans or window trickle vents are commonly installed. However, they are rarely sufficient in winter. Windows remain shut, reducing their effectiveness.

Homeowners deal with black mold on walls and ceilings. They suffer from respiratory problems. They often rely on stopgap solutions like bleach and dehumidifiers. The promise of sustainable living in a high-performance home quickly fades when the environment becomes unhealthy. True sustainability means designing homes that work in practice and theory. These homes should balance energy efficiency with the need for fresh air. They must also guarantee healthy living conditions.

The government’s energy advice encourages draft-proofing as a key way to reduce heat loss and cut bills. Yet this overlooks airflow’s crucial role in preventing damp and mold. Without providing alternative ventilation, sealing a house from draughts can backfire. Blocking chimneys and sealing gaps can hold moisture, accelerating the very problems these measures were meant to solve.

These risks are already becoming clear. In early 2025, the UK government banned nearly 40 construction firms from installing insulation. Widespread reports of shoddy workmanship, including exposed insulation and insufficient ventilation, prompted this action. Homeowners caught in these failings have been unable to sell their homes. They can’t remortgage them. As a result, they stay stuck with properties suffering from damp and decay.

Despite these warning signs, many developers continue to build large estates with air-source heat pumps but no proper ventilation systems. MVHR remains rare outside of high-spec, bespoke eco-homes. Instead, most estates rely on basic fans in bathrooms and kitchens. They use minimal window vents. Sometimes, they have little more than the bare minimum to meet building regulations.

Developers avoid MVHR to keep costs down. Still, the industry lacks the knowledge to design genuinely low-energy, breathable homes. Building regulations reinforce this problem by focusing on insulation standards rather than making comprehensive ventilation mandatory.

Until this changes, new-build homes will continue to be plagued by damp, mold, and poor indoor air quality. The cycle will repeat as buyers move into brand-new properties. They will only discover the uncomfortable reality of living in a sealed box without adequate airflow.

Stronger regulations and a commitment to whole-house ventilation are essential. Without these, the promise of sustainable housing will remain an illusion. The homes being built today will not last a lifetime. They will fail to offer a healthy place to live from the very start.