No house is immune to water damage, but historic homes are even more prone to dampness due to their age, general deterioration of the property and how they have been repaired over the years. 

That is why those who own heritage houses need to ensure they understand how to look after the building to avoid further damage and to keep their home in good condition for as long as possible. 

When does moisture lead to excess dampness?

All buildings have moisture and a structure with good-quality fixtures and fittings will be able to manage a certain level so it does not lead to deterioration. 

However, it becomes a problem when there is too much moisture, resulting in excess dampness

This can occur when water accumulates in a building, as a result of poor engineering, faults within the building structure, leaking drains or utilities, the outside environment, wrong maintenance and the activities of those living in the home. 

Houses located in areas of flooding are also more likely to have problems with dampness due to excess groundwater. Whatever the cause, it is important to have the problem professionally looked at, as the solution will depend on the origins of the moisture.

If the wrong work is carried out because the diagnosis is incorrect, this can actually make the problem much worse in the long run. 

Why does dampness cause problems?

There are many reasons why this causes problems, not just for the brickwork and timber, but also for those living on the property. 

Historic England recognises that excessive moisture can lead to serious deterioration of building fabric, including the corrosion of metals, decay of timber and even insect infestation. 

It can also result in mould growth, wood-decaying fungi and collapsing plaster from water penetration through gutters. Essentially, it causes buildings to start falling apart, as the materials they have been built with begin to wear away. 

Having excess dampness in the house can also cause serious health problems. According to the NHS, these include respiratory infections, allergies, asthma and a weakening of the immune system. 

This is because moulds, caused by excess moisture in the property, produce allergens and can even be toxic. Therefore, touching or breathing in these allergens could result in an allergic reaction, such as a rash. Moulds can also be irritating and bring on asthma attacks. 

Certain groups of people are even more susceptible to ill health from living in a damp house, including babies and children, and the elderly. Those with skin problems like eczema, respiratory conditions, or a weakened immune system, including cancer patients undergoing chemotherapy, are particularly vulnerable to the negative effects of mould in a property. 

Therefore, it is imperative to reduce excess moisture in a property, not only to maintain the integrity and longevity of the home but also for the quality of life of those living in it. 

Usual damp-proofing strategies

In the quest to safeguard modern properties from the damaging effects of water ingress, damp specialists often recommend employing methods such as damp injections, damp-proof membranes and the application of masonry weather-sealing products on bricks to effectively repel water. 

However, when it comes to traditionally built properties, these well-intended strategies can, paradoxically, create more harm than good. 

Although the treatments may initially decrease water penetration, they also inadvertently trap moisture within the brickwork, leading to an escalation in dampness and subsequent masonry decay. 

This counterproductive outcome can have serious ramifications on buildings that have potentially endured for centuries, compromising their structural integrity and longevity.

Tanking slurries, damp-proof paints and water-resistant renders may all be effective on modern homes, but when it comes to lime mortar-built brick or stone houses, a different approach is required.

How to reduce damp in lime mortar-built brick homes

The intricate relationship between older properties built with lime mortar and airflow cannot be understated, as both have a significant impact on moisture regulation within these buildings. 

The natural process of air movement, both inside and outside of the property, is essential for drawing moisture through the lime-plastered walls, allowing the water vapour to escape through the lime mortar joints that connect the brickwork. 

This vital interaction is often disrupted by modern damp-proofing solutions, which, despite their effectiveness in contemporary homes, can worsen dampness issues in older properties. 

By hindering the necessary airflow, these solutions inadvertently trap moisture within the structure, intensifying the very problem they aim to resolve. 

Thus, it is crucial to consider the unique characteristics of older buildings when exploring damp-proofing options, ensuring a harmonious balance between preservation and practicality.

This could be why many historic properties are suffering now, as cement mortar has been used in repairs for over 100 years, which makes structural problems worse in these homes, not better. 

Therefore, traditional lime mortar-built brick or stone homes need to be repaired with another porous material that enables the house to breathe. 

This is why lime plaster and porous paints like limewash or clay paints need to be used on older buildings, as other choices can trap moisture within the house causing condensation and, subsequently, mould and decay. 

Can insulation make damp problems worse?

In a day and age when everyone is concerned about the environment and energy bills, it is easy to see why homeowners want to improve insulation in their property. However, certain types of insulating materials can cause damp problems in older buildings. 

For instance, roofing felts can lead to condensation by providing a barrier to moisture, spray foam insulation in the loft can restrict air circulation to the roof and, while fibre-glass insulation stops cold air from getting into the house, it also provides a barrier for moisture and airflow to the outside.  

Therefore, if you have installed insulating materials to reduce the amount of energy use your property requires, you might cause the structure to deteriorate by preventing water vapour from escaping. 

The best way to ensure your house can stay warm during the winter months, as well as avoid problems of rotting timber and corroding metals is to use naturally-occurring materials as insulation. 

For instance, sheep’s wool has been a traditional choice for hundreds of years, as it can store heat, as well as allow moisture to pass through. Therefore, it prevents condensation from occurring and avoids subsequent water build-up. 

The only way you can be sure your damp-proofing solutions and insulating methods are suitable for your traditional home is to call lime mortar specialists who can advise you on how to avoid damp problems within your property.

If this article is still not enough and you would like to learn more about dampness, check the series of videos “A Common Sense Approach to Damp” by Historic England. You will learn everything about dampness in detail.

A Common Sense Approach to Damp Part I

A Common Sense Approach to Damp Part II