Tree Cassyn Property Solutions

26/07/2025

Discover the Technical Advantages of Lime Render 🏛️

From vapour permeability to enhanced building longevity, our latest article breaks down why lime render remains the gold standard for breathable, durable construction.

Whether you're working on heritage projects or sustainable new builds, this expert guide explains how lime render supports structural integrity, reduces moisture issues, and helps maintain the hygrothermal balance of the substrate.

www.ecorend.co.uk/benefits-of-using-lime-render-in-construction

24/07/2025

Do you live in a traditional building? By this we mean solid stone wall building - one of the many beautiful Victorian terraced houses around the island for example. Well, SPAB is a goldmine of helpful information. This link covers a topic we see so often, and really is worth a read, as it's really relevant if your home has had (well meaning, but inappropriate) work using non breathable materials. Traditional buildings aren't just "ancient", they provide homes for many of us, and the use of non breathable materials is a really common source of dampness.

Why is cement so often bad news for old buildings? 🛠️

Much of the guidance we give on our Technical Advice Line concerns buildings that had their original lime render removed in favour of modern cement coverings.

Lime render is a traditional material, known for its flexibility and breathability. This allows traditionally constructed buildings to manage moisture naturally, in the way they were designed to.

In contrast, cement render, while strong and durable, can trap moisture, potentially leading to damage over time.

So, how can you tell if a render is cement or lime? 🔍

Although a range of finishes exists with each, cement has a more uniform appearance, and corners and details are sharper and more defined.

They also weather differently. Cement renders often fail in patches and detach from the wall, whereas lime renders erode back gradually in a more even manner.

For more information, including what to do if there's cement on your old building, check out our detailed guide: https://www.spab.org.uk/advice/lime-renders-vs-cement-renders

📷 Lime pointing © Ralph Hodgson

23/07/2025

12/05/2025

Living in or buying an old stone property? It doesn’t have to be damp.

It’s a common myth that old stone buildings will always be damp, but that’s simply not true. While these homes have stood, in many cases, for centuries, they do require a different approach compared to modern houses - especially when it comes to managing moisture.

Dampness isn’t just unpleasant - it can harm both your health and the building’s structure. Many damp issues we see in stone buildings aren’t due to their age, but rather from well-meaning repairs done with the wrong materials. Using non-breathable materials like cement, gypsum, or plastic paints can trap moisture inside walls, leading to mould, rot, and even misdiagnosis of “rising damp.”

The good news? With the right care and materials, these beautiful old properties can be warm, dry, and healthy.

Why do old stone walls often seem damp?

Two words: Interstitial Condensation.

This might sound technical, but it’s actually a simple process. Solid stone walls behave very differently to modern cavity walls. When warm, moist air from inside your home moves through the thick stone walls, it can hit a colder layer inside the wall. That’s where water vapour condenses into liquid water - inside the wall, hidden from sight.

Over time, this can weaken the stone, erode mortar, and encourage mould growth. If left to build up, it also often leads to water in liquid form forcing its way through to the surface, often lower down due to gravity, mirroring the type of symptoms seen in more serious forms of “true” dampness, such as penetrating damp and rising damp. Water as a liquid will do this whether breathable materials are used or not - in fact, we most often see it happen where non-breathable materials are used, since they can often be the cause of the build up of moisture. Salt deposits are also often left behind during this process, which can lead to yet more damage.

Why do materials matter so much?

Think of a stone wall like a sponge - it can hold moisture, but it also needs to breathe and dry out naturally. When you seal it up with modern, non-breathable materials, it’s like wrapping that sponge in clingfilm, but it eventually leaks through the joints.

Using breathable materials allows moisture to escape in its vapour form, reducing the moisture buildup inside the wall. Once the wall temperature increases back above dew point, water diffuses away in its vapour form, provided breathable materials are used. The use of non-breathable materials prevents this from happening, locking the water inside the wall as a liquid. Over time, water in liquid form will fall due to gravity, and will slowly soak through the lower part of the wall (whether breathable or not), and the resultant visible symptoms can mirror those seen for more serious “true” damp problems, such as penetrating damp or even rising damp.

How to keep your old stone home dry and healthy

1. Always use breathable materials

Lime Mortar & Lime Plaster:
When renovating or repairing, always use traditional lime-based products instead of cement or gypsum for solid wall structures. Lime allows the wall to breathe and helps moisture evaporate naturally. Some modern lime-based alternatives exist too - they’re generally better than cement, though traditional lime is still preferred, and in many cases no research into their longevity and effectiveness has yet been possible.

Natural Paints:
Use finishes like limewash, clay paint, or mineral paints. Avoid plastic-based paints, especially over lime plasters, as they block breathability.

2. Avoid impermeable products

No Cement Renders or Mortars:
Cement traps moisture and can damage the stone over time. Always use softer, weaker materials when pointing than the stone itself, so the mortar takes the wear, not the stone.

No Waterproof Coatings or Tanking Slurries:
Applying waterproof sealants or cementitious tanking products is a common but harmful mistake. These don’t solve the root cause and will usually make damp problems worse. If you’re in need of a waterproofing solution for a sub-ground-level area, such as a cellar, alternative forms of structural waterproofing should be pursued, if needed (though we’ve seen plenty of cellars and basements which haven’t needed such solutions).

3. Ensure good ventilation

Keep air moving:
Use air bricks, trickle vents, and maintain good cross-ventilation. Old chimneys should stay vented at both the top and inside, even if the fireplace is blocked off.

Humidity-controlled ventilation systems:
Consider installing systems that automatically manage humidity levels inside your home.

4. Apply steady, gentle heating

Keep it consistent:
Stone buildings do best with low, constant heating - aim for a base temperature of around 15℃. While this might feel low, it helps warm the walls gently, reducing cold spots where condensation forms, and reducing the likelihood of dew point being reached in the substrate close to the internal wall surface.

Avoid short bursts of intense heating:
This can worsen condensation (the temporary increase in air temperature will hold more moisture - but rapid drop in temperature will result in more condensation). Instead, think of your home like a storage heater - slow and steady warmth helps the thick walls retain heat over time.

If costs are a concern:
If you can, use solid fuel stoves to supplement your heating, and ensure good airflow when they’re in use.

12/05/2025

It’s been a while since we shared any updates (if you know us, you’ll know we’ve been keeping busy). But one of the reasons we have social media is to inform, and we’re aiming to do a bit better on that front going forward. We're not here for the likes - our goal is simply to build up a useful bank of information that might help you out one day.

First up - Woodworm.

It’s a topical subject right now, as we’ve entered “emergence” season. This is when larvae, after spending years inside the timber, finally pupate and emerge as adult beetles. They bite their way out through what are known as emergence or flight holes, then get on with mating and restarting the cycle all over again.

If you’re buying or selling a property and the surveyor spots signs of beetle activity - often just the presence of these flight holes - you might find yourself needing a specialist survey, or a quote to treat the infestation.

By far the most common culprit we encounter is the Common Furniture Beetle (the name says it all), or for the budding entomologists, Anobium Punctatum. This species can be introduced into a home via infected furniture, hence the name, and favours softwoods and some European hardwoods. It typically sticks to the sapwood - the younger, outer part of the timber - which is softer and more nutritious, rather than the heartwood, which is denser and less appealing to them. Notably, older houses tend to have been built with older, slow grown timber, which contains a greater amount of heartwood, and this results in a certain amount of natural immunity. Modern construction timber is grown much faster to meet modern demands, and hence contains mostly sapwood, and needs to be “treated” before use. But that “treatment” can wear off, and doesn't pe*****te the entire timber, even though it's applied under very high pressure. But we see beetle activity in a wide range of properties, old and new.

The life cycle of this beetle can last 2 to 5 years in the larvae stage, during which they do the real damage, munching away at the timber as they tunnel through it. Each adult beetle can then lay up to 100 eggs, so if conditions are right and the infestation goes unchecked, things can escalate pretty quickly.

How do you spot them?

The most obvious sign is the presence of circular flight holes, typically 1 mm to 2 mm in diameter.

Often, these holes are historic, especially if they look dark or aged and no other evidence is found, meaning the infestation might already be long gone or the area has dried out - in these cases, no treatment is needed.

Fresher holes tend to look lighter in colour. If you also spot bore dust (called frass), which looks like sawdust but is gritty and lemon-shaped under magnification, that’s a strong sign of current activity. Frass can appear in small piles or hanging on to nearby cobwebs.

What does treatment consist of?

The most common treatment is spraying a diluted insecticide.

While DIY products are available, professional treatment is usually required during house purchases, especially to meet lender requirements.

Our preferred treatment involves the use of a micro-emulsion product, which is safer than solvent-based chemicals.

Thorough preparation is key, including deep cleaning of affected areas - vacuuming timbers, removing debris, cobwebs, and dust.

A micro-emulsion product is a type of water-based insecticide formulation where the active ingredients are mixed into extremely small droplets (microscopic), creating a stable mixture that can easily pe*****te surfaces like wood.

Why is it considered safer?

Low odor and low toxicity: Since it's water-based, it doesn't have the strong chemical smell or high toxicity of solvent-based treatments.

Better pe*******on: The tiny droplets can soak into timber more effectively, ensuring insects are reached without over-saturating the area.

Environmentally friendlier: Micro-emulsions are designed to minimize harm to people, pets, and the environment while still being effective against pests.

This makes it a safer, more modern approach, especially suitable for indoor treatments or in sensitive environments.

What protection, or warranty, should you expect on completion of the treatment?

You should expect a guarantee for the work, ideally insurance-backed, which protects you even if the contractor stops trading during the guarantee term.

Most lenders require a 10-year insurance-backed guarantee, which is quite standard in the industry.

Treatments by Tree Cassyn include our 10-year guarantee backed by QA National Warranties, a highly respected, market leading provider of contractor guarantees.

We’ve included some images below:

An adult Anobium Punctatum beetle - often found on window sills, as they’re attracted to light coloured surfaces. They’re small (3 mm to 5 mm), dull brown, with rows of pits on their wing covers.

A graphic showing heartwood vs. sapwood..

A picture from a recent loft inspection showing a purlin where activity is heavy in the sapwood but absent in the heartwood - highlighting why only certain parts of a timber may be affected. The holes here were actually historic and inactive, but there was fresh activity elsewhere in the same loft, including recently deceased adult beetles on a nearby window sill.

A close-up picture from an inspection featuring heavy frass piles, a clear indicator of an active and significant infestation that needed treatment.