As flooding risk increases across the UK, the need for an innovative solution to provide sufficient resilience to older buildings becomes even more prescient. Daniel Fitch, Technical Sales Manager Packed Products at Tarmac, explores why innovative lime plasters need to be at the forefront of every renovation conversation.

Flooding is increasingly becoming an unfortunate but common occurrence in the British winter. Due to climate change, extreme rain is leading to unprecedented amounts of flooding with flood risk expected to increase for 73% of affected properties by 2080, while the probability of flooding is set to increase by a further 8%.

While many older homes were designed and constructed to be resilient to flooding, the increased regularity and intensity will pose a problem to these buildings, if not during the actual flood, then afterwards during the delicate process of remedial works. Tackling this problem head-on means talking about plaster and specifically, lime plaster.

The known options

The modern housebuilder and renovator have a variety of cement-based plasters at their disposal, each with their different advantages and challenges. The most common ones tend to be gypsum plaster, clay plaster and hydraulic lime.

One of gypsum plaster’s main advantages is its use of gypsum, a readily available raw material, making the plaster highly accessible. Furthermore, when readily made gypsum plaster requires no curing time, saving water during the plastering process. Clay plaster’s unique, matte finish is popular amongst many, and its lack of toxins, polymers, VOCs, formaldehydes, and plastics is very desirable also.

While these plasters have their benefits, within the context of flooding and flood risk, lime plasters have the upper hand. For example, due to its setting by hydrolysis, hydraulic lime plaster can be more practical in damp conditions. Simple lime plasters are known for their breathability, meaning they take out moisture from the air when there’s too much, and release it back when the air gets too dry, inarguably creating a healthier environment. 

Innovation in plaster

When looking at more innovative lime plasters, such as Tarmac’s Limelite, there is a combination of the traditional benefits of lime products with the ease of use of modern materials. Ideal for flood-prone properties and suitable for older housing stock, Limelite ensures flood resistance against the floods of today and tomorrow. 

Lime plaster’s key advantage over other plasters is its breathability. Conventional gypsum plaster is hygroscopic, meaning that moisture from the atmosphere or substrate is absorbed and retained. Limelite allows for natural moisture regulation, working with the fabric of a building and allowing the walls to breathe out moisture, reducing mould growth. But compared to traditional lime plasters, Limelite has quick-setting properties which means additional plaster coats or paint can be applied in just 24 hours. In the event of a flood, people can return to their homes quickly, an understandable priority for many.tar

Ease and efficiency of application is a priority for many housebuilders and renovators and is something that has typically been considered a challenge for traditional lime plasters. However new inventive plaster creations have been designed with various skill levels in mind, resulting in a more user-friendly process. Limelite in particular is 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.

Myth busting

One of the most common myths surrounding traditional lime plasters is that there is a trade-off between flexibility and strength. However, lime plaster is very long-lasting. Because of its chemical composition, lime plaster will become stronger over time as calcite crystals form. tar, the plaster will form a tight bond with the wall material due to being made up of small particles that are able to get into the smallest of gaps and spaces.

Expense is another aspect of lime plaster that can sometimes be overemphasised without an explanation of the long-term cost-effectiveness. While there tends to be a higher upfront cost when requiring lime plaster, compared to the relatively lower upfront costs of gypsum and other non-lime plasters, newer lime plasters, such as Tarmac’s Limelite, have rapid drying times making lime plaster a more cost-effective investment. Furthermore, combined with lime plaster’s flexibility and long-lasting properties, the finish will be less likely to crack and, when properly cared for, can endure for decades.

As flooding becomes more prominent and frequent, the cost-effectiveness of purchasing and applying lime plaster only increases. Lime plaster is ideal for moist, damp environments due to its breathability and the lime content makes the plaster naturally aseptic, preventing mould growth. Tarmac’s Limelite specifically provides a barrier to salt and efflorescence, so any moisture that does evaporate does not leave a less-than-aesthetic finish. Additionally, Limelite prevents the corrosion of metal fixtures, such as angle beads and lath, a key advantage for renovators of older and historic buildings where protecting original features is crucial.

Flooding in the limelight

Flooding is going to become even more frequent and challenging in the coming years. While extreme weather can feel both unpredictable and uncontrollable, the solution to protecting and making flood-prone properties more resilient can be simple and easy to apply. Lime-based plasters are back in the limelight, with innovative compositions bypassing previous issues and challenges. 

The solution of a traditional lime plaster combined with modern efficiencies often seen in gypsum or clay plasters, lies in new, innovative lime plasters. There may just be a clear path to weather this particular climate change storm.