From October 2025, social landlords must rapidly address serious damp and mould risks. Luke Brooks of Tarmac shows how lime plaster systems are effective as a ‘people-first’ alternative.

Social landlords will already be well aware of Section 42 of the Social Housing (Regulation) Act 2023, known as Awaab’s Law, which was passed as part of the Government’s mission to transform the safety and quality of social housing.

From October 2025, all social landlords will be forced to investigate and fix dangerous damp and mould in set time periods, as well as repair all emergency hazards within 24 hours. Measures to address other dangerous hazards will then be introduced under a step-by-step approach to make the law stronger.

Failure to comply could lead to court action, a major shift which should help to drive a better approach to achieving quality in social housing in all sites across the UK.

Highlighting the problem

Social landlords already have a duty to keep their homes fit for human habitation and to remedy disrepair, including making sure that homes meet the Decent Homes Standard, but damp and mould unfortunately remains a common issue in the sector.

Awaab’s Law honours two-year-old Awaab Ishak, who tragically died following prolonged exposure to damp and mould, but it “will set clearer and stronger laws to ensure that tenants are living in safe homes”, according to
the Government.

Findings published by the Government in 2023 following Awaab Ishak’s death show that around 3-4% of the four million social housing homes in England had at least some notable damp and mould, 1-2% had serious (HHSRS category 2) damp and mould problems, and a further 0.2% had the most serious (HHSRS category 1 level) problems, which would fail the Decent Homes Standard. The most recent English Housing Survey found damp problems in 7% of social homes in 2023-24, an increase of 3% since 2019.

Significant improvements have already been made under various funding programmes, but more work is needed ahead of the new legislation.

Lime plaster – covering the issues

Of course, social landlords can use a number of improvements across the home to improve energy performance and reduce the risk of damp and mould. The WMCA programme included fixing leaking roofs, windows and doors, adding new insulation measures and improving heating systems. Roof space ventilation and bathroom fans also help to remove condensation and tackle damp issues, while retrospective damp proof measures such as the installation of a damp proof course are also an option, albeit costly and time-consuming, with no guarantee of a successful outcome.

Damp and mould is caused by excess moisture remaining on walls, thus creating the perfect conditions for mould growth. Solid brick and stone walls are particularly prone to this as the cold surface of the wall encourages airborne moisture from cooking, washing or exhaled breath to condense. The lack of a damp proof course will only add to the issue. However, another increasingly common option that spans the property is the use of modern, breathable lime plaster.

Lime plasters have a number of positive attributes, including the ability to remove moisture from the air when there is too much, and release it back when the air gets too dry, creating a healthier environment that allows the walls to breathe out moisture and reduce mould growth. This is made possible thanks to the microporous structure, which enables controlled vapour diffusion and offers resistance to liquid water penetration.

In contrast, conventional gypsum plaster is hygroscopic, which means that any moisture from the atmosphere or substrate is absorbed and retained. Without correct insulation measures, this can contribute to damp and black mould. Widespread installation of double glazing may have improved heat retention and offer sound insulation across our ageing social housing stock, but it can also diminish ventilation and increase humidity levels; one limitation of gypsum plaster.

Lime plasters are designed for older buildings, which are common in social housing, and can even make older buildings warmer and easier to heat. Due to the use of expanded perlite, Limelite renovating plasters, for example, deliver thermal conductivity value on average three times lower than gypsum plasters, which improves the insulation properties of the wall.

Added benefits

There are benefits for contractors too. Lime plaster is often misunderstood as being difficult to apply, but in fact can be particularly user-friendly and easy to handle. Modern lime plaster systems have been designed with various skill levels in mind, resulting in a more user-friendly process. Systems can be less than half the weight of a sand and cement plaster, and can also be applied to both modern and traditional substrates, including masonry, block, stone and wooden lath. Additionally, and perhaps most importantly for contractors, lime plasters are quick drying, with modern plasters having the capability of drying in as little as 24 hours.

The path to success comes down to correct material choice. With enhanced understanding of lime plasters and access to premium products, social landlords have another effective tool in their armoury against damp, ahead of the introduction of new legislation. For occupiers, that can only be a good thing.

Luke Brooks is senior commercial manager, specialist packed products at Tarmac