If you’ve landed here because you’re looking at insulating an older property then you need to know one thing first – Insulating an older property is one of the most misunderstood areas of traditional building work — and one of the most consequential if it goes wrong.
Covering Devon & the South West, we carry out breathable insulating lime plaster work across Shropshire and the surrounding counties, helping owners of period and traditionally constructed properties improve thermal performance without compromising the way their buildings manage moisture.
Not every insulation solution is suitable for a solid-wall building. Many modern systems trap moisture, cause interstitial condensation, and create the very damp problems they were supposed to solve. Every insulating lime plaster system we install is specified with breathability and compatibility at the forefront — because getting it wrong is far more expensive than getting it right.
Solid-wall buildings—such as cob cottages, Dartmoor stone farmhouses, Victorian brick terraces, and period townhouses—were never designed with a modern vapour barrier in mind. They manage heat and moisture through the fabric of the building itself, and any internal insulation system needs to work in harmony with that principle. Fit the wrong insulation product and you don’t just waste money; you risk trapping moisture inside the wall structure, accelerating rot in timber lintels and floor joists, and creating persistent damp that is difficult and costly to resolve.
The right insulating lime plaster system improves thermal performance, provides essential hygroscopic buffering, and leaves the wall able to breathe freely. The wrong one seals it shut. That distinction is everything in an older Devon property, and it’s why material selection and correct specification matter just as much as the application itself.
Before specifying or applying an insulating lime plaster system, an initial on-site evaluation is essential. Every historic building in Devon presents unique challenges—whether it’s original cob, granite, soft sandstone, or rubble masonry. Existing damp levels and wind exposure directly determine which breathable insulation system will perform safely. An approach that suits a dry Victorian property in Totnes could cause severe moisture trapping if applied to a damp stone farmhouse in North Devon.
Insulating traditional solid-wall properties requires tailored solutions, which is why I don’t push a single off-the-shelf product. My recommendation is always based on a practical diagnosis of what the specific building fabric needs.
A lightweight, well fibred breathable insulating render suitable for application to solid masonry walls. Cornerstone provides a meaningful improvement in thermal performance while remaining fully vapour-permeable — making it a practical option for stone and brick properties where internal wall depth is limited and breathability is non-negotiable. This is applied much in the same way that a traditional lime plaster is applied – A Scratch Coat, Float Coat and Final Skim Coat. Cornerstone insulating render is by far one of my favourite options when it comes to insulating older properties. You can read more information about the product here.
Warmcote is a pre-mixed, non-hydraulic insulating lime plaster from Best of Lime, formulated specifically for use on traditional solid-wall buildings. It combines thermal improvement with the breathable, hygroscopic properties of lime — applied as part of a compatible lime plaster system, it improves comfort and reduces heat loss without introducing moisture risk. This again is applied much like a traditional three coat lime plaster system and can also be applied over any boarded systems like woodwool or woodfibre and cork as a further layer of breathable insulation.
Insulating lime plaster isn’t a straight swap for standard lime plaster — the specification, preparation and build-up vary depending on the system, the substrate and what the building needs. Here’s a general overview of how a typical installation comes together:
Before any product is selected, the wall condition, moisture levels and existing construction need to be properly understood. The wrong system on the wrong wall causes problems — this stage is where the right approach is established
Existing incompatible materials are removed, the substrate is cleaned and any remedial work carried out before installation begins. No insulating system performs well over a compromised base.
Each system is installed to specification, with multiple coats if required to build up plaster thickness and increase thermal value build-up for the product being used.
All systems are finished with a compatible breathable lime plaster coat — ensuring the completed wall performs as a unified, vapour-open system from substrate to surface. This is usually a fine lime putty skim but other systems use dedicated top coats.
If your property was built before around 1919 with solid walls, the answer is almost certainly yes — with the right system. Modern rigid foam boards and impermeable renders have no place in a traditionally constructed building, but that doesn’t mean you have to choose between comfort and building health. Breathable insulating lime plaster systems are specifically developed for this scenario, and when correctly specified and installed, they make a genuine difference to how a building feels to live in.
If you’re in Devon and you’re considering internal insulation on a period property, particularly a listed building or a stone cottage — I’d strongly recommend having a conversation before committing to anything. The wrong choice at this stage is expensive to undo.
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Every property and every job is a unique story, requiring an in-person survey to enable us to give you the best advice. To arrange a tailored on site quote, please use the form below or give us a call to get in touch.
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From transforming just one problematic wall in a thatched cob cottage in Tavistock through to complete lime restoration projects for country estates around Totnes, we handle a wide variety of work across Devon. Here’s what clients have to say about working with us!
Insulating lime plaster throws up plenty of questions — especially when you’re trying to weigh up different systems, understand what’s genuinely breathable, and work out what’s right for your property versus what’s just being marketed as a traditional solution. Below, I’ve answered the questions I hear most often from Devon homeowners considering insulating lime plaster for the first time. If yours isn’t covered, give me a call — I’m always happy to talk through what your walls actually need before any system is specified or committed to.
Standard lime plaster is applied primarily to protect and finish a wall surface. Insulating lime plaster systems incorporate thermally efficient materials — whether that’s lightweight aggregate, cork, or insulated board — to improve the thermal performance of the wall at the same time. The key distinction from modern insulation systems is that everything remains breathable and vapour-permeable throughout.
Yes, though the degree depends on the system chosen and the existing wall construction. Solid stone walls can lose significant heat through the fabric of the building, and even a moderate improvement in U-value makes a real difference to comfort levels in older properties. The added hygroscopic benefit of lime also helps regulate internal humidity, which contributes to how warm a room feels day to day.
In most cases yes — breathable insulating lime systems are among the few internal insulation options that conservation officers and historic environment consultants are comfortable with, precisely because they don’t introduce impermeable barriers or risk damaging historic fabric. That said, listed building consent requirements vary, and it’s always worth checking with your local authority before proceeding with any insulation work.
Warmcote is a pre-mixed insulating lime plaster from Best of Lime, designed for direct application to solid masonry walls. It’s a good option where wall depth is limited and a board system isn’t practical — it adds thermal resistance as part of the plaster build-up without introducing any vapour barrier. Best suited to brick or stone walls in reasonable condition where a modest thermal improvement is the goal.
A correctly specified breathable system should not cause damp problems — in fact, improving the thermal performance of a cold wall can reduce condensation on the internal surface. The risk comes from using impermeable systems that trap moisture within the wall structure. Every system I install is vapour-permeable, and I always assess existing moisture conditions before specifying anything.
It can absolutely be approached room by room — many clients start with the coldest or most problematic room and extend the work over time. There are some thermal bridging considerations to be aware of at junctions between treated and untreated walls, but these are manageable with correct detailing. I’ll talk through the options and any implications as part of the initial assessment.
Both. Not every job needs a full strip and start-again — sometimes a room has isolated areas of failure that can be cut out and patched correctly without touching the rest. Where the existing plaster is predominantly sound and the substrate is compatible, targeted repairs are a perfectly valid and cost-effective approach. The key is making sure any repair is done with compatible materials and proper preparation, otherwise you’re just deferring the problem.
Three-coat lime plaster systems using traditional non-hydraulic lime mortars.
Improve comfort and thermal performance of older properties whilst maintaining breathability.
Traditional cob repairs and lintel replacements
Breathable repointing for stone and brick buildings using appropriate lime mortars.
Currently Accepting New Projects
Traditional Lime Plastering and Heritage Lime Pointing Services for Devon’s Older Properties.
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