Cedral’s Lisa Grosse explains why overheating and resilience are key factors when making decisions about the facade and roof of your home.
Homes in the UK weren’t designed for the extreme heat that has been setting records, and which is projected to become a regular occurrence. The Local Government Association has found that 20% of homes in England experience overheating issues now, even during cooler summers.
Nearly 38% of the country’s residential properties were built before 1946 when the norm was to construct to trap the sun and minimise heat loss during mild summers and cool winters. More recently residential design has featured expanses of glass to maximise the sunlight with conservatories, skylights and large glass doors. At the same time, government data shows that two thirds of the homes in the UK need better insulation which would help mitigate the effects of heatwaves.
With more intense sunshine, higher temperatures and increased radiation, the UK renovation and homebuilding sector is having to re-evaluate material choices as well as design features to ensure that homes are more resilient. Such extremes particularly affect the performance and fabric of south facing facades. Designing buildings that remain cool in the summer and are efficient for colder weather has become more of a priority to comply with building standards.
While most building materials are designed to withstand some degree of expansion and contraction, excessive heat can push these materials beyond their limit. The impact of expansion and contraction on the building’s fabric can also adversely affect the quality of the indoor environment and the wellbeing of the occupants.
Heat or over exposure to sunlight, especially for south facing facades, can result in warping and bulging, and can even affect the structure. For example, a timber facade can not only bleach in colour in consistent direct sunlight but it can also warp and expand. This can damage or create gaps in the facade and as a consequence this could result in a leak later in the year. Stone is highly robust, but like wood, can discolour as a result of constant exposure to extreme fluctuations in temperature.
The materials used for residential roofing in the UK are also facing challenges because of more extreme weather. Increasing temperatures could cause blistering or cracking on roof tiles and slates. The sealants could also be affected. This isn’t just about the visible damage caused by heat.
At the same time we are seeing increases in rainfall and wind speeds which could potentially compromise the roof’s durability and result in costly maintenance in the future. The Met Office measured the highest amount of rain for any 18 month period in England from October 2022 to March 2024, since its records began. The longer and heavier periods of rain have implications for the robustness of roofing tiles and fixings. Older roof structures, for instance, may not have the capacity to support heavier tiles if there are more prolonged periods of stormy and wet weather.
With the UK becoming warmer, the choice of material and design for a home’s facade will make a tremendous difference in creating an energy efficient, climate-responsive building. The most frequently used options include, either used on their own or in various combinations: timber, stone, brick, metal, weatherboard, concrete, and glass. And a trend we have seen growing in popularity is fibre cement cladding which has undergone stringent testing to ensure its durability under extreme weather conditions. For roofing, the most popular material options have
been concrete tiles, clay tiles, asphalt shingles, metal, and increasingly, fibre cement tiles.
Each of these has their own pros and cons in terms of the protection they provide their durability under extreme conditions, their cost and value, both from initial installation to maintenance and replacement.
A ventilated facade makes it easier for your home to be cooler during summer and warmer during winter. An example is the use of a ventilated rainscreen system used with cladding. Having effective ventilated walls can improve thermal efficiency of a home by helping to circulate air flow which in turn helps to regulate the temperature and improve conditions indoors. In hot weather, air can rise to the top leaving space below for cool air to enter and keep the building cool.
Other advantages of installing a ventilated wall include reducing structural movement of the building and extended lifetime of the facade. In wet weather, the air flow allows the exterior walls to dry quickly, preventing a build-up of condensation. Ventilation around windows and doors can also reduce condensation and humidity coming from inside and outside the building.
Tips for adapting your home to a changing climate
As you are designing and specifying your new home or looking to make changes or upgrades, bear in mind these points:
- Opt for heat-resistant materials where possible
- Ensure that existing structures have some allowance for heat expansion
- Think about the importance of insulation for walls, windows and the roof cavity which can help to stop heat flowing through the building’s fabric
- Take the orientation of the building into account, especially south facing walls
- Look at traditional materials and building methods which have been effective in hot climates. These include concrete, brick, tile and thick plaster as well as the use of lighter coloured materials on the exterior to reflect the sun
- Incorporate active shading to keep the heat out – everything from shutters and awnings to deciduous trees
- The impact of climate change varies by region. Homes in coastal areas, for example, need materials that can withstand high levels of moisture, salt and potential storm surges.
Since 2021 government guidelines for new homes have included minimising excess sunlight in the summer, for example by setting limits for window sizes as a proportion of the floor space.
The new Future Homes Standard’s ‘fabric first’ approach, applicable to all new homes built from 2025, with minimum standard U-values addresses improvements to insulation and efficiency. For existing properties, extensions and the replacement of thermal elements such as walls, floors or windows have to meet the new fabric efficiency standards. Achieving these will be challenging, but innovations in materials and construction techniques are providing new solutions.
Lisa Grosse is brand manager at Cedral