With over four million properties in the United Kingdom dating back to Victorian and Edwardian periods alone, British heritage is on display throughout the buildings we work and live in. While these properties serve the purpose of keeping history alive, they are not without issue, with damp-proofing being required in old stone buildings for a range of different reasons.
This could be as a result of general wear and tear in the materials, such as cracks that form naturally in the stone over the years, or because of the presence of an outdated DPC (Damp Proof Course). In buildings built before 1919, it wasn’t uncommon for the DPC to be made from materials such as slate, bitumen, jute or hessian.
Period properties were designed to allow as much ventilation as possible, which is why such material was used in its construction. It is also why, when modern methods and materials are used for maintenance works, damp issues can become prevalent as the new techniques and supplies are not compatible with the property's initial building work.
Whereas in the present day, DPCs are made from synthetic materials which are designed to last for around 20 years, slate was a popular choice previously due to its water-resistant properties. However, unlike synthetics, slate can crack easily, which then makes the DPC penetrable.
Once the DPC has been damaged, this allows for moisture to rise through the stone wall, thus causing a rising damp problem. If you go back even further in time to Georgian architecture, you will find no actual physical DPC. This is because the Georgians focused much more on ensuring their buildings had good ventilation and kept moisture levels down to a bare minimum.
During the latter part of the Victorian era, in 1875, DPCs were made compulsory in all new buildings in London. Early builds during this era were highly susceptible to condensation due to the presence of large cold surfaces, only made worse by the high proportion of timber work in these buildings, which would then begin rotting away due to the damp and high moisture levels in the building.
Many Victorian houses, particularly those to first feature a DPC, can suffer from damp issues in the modern-day because the DPC has been bridged externally due to an increased ground level. Over the years, the level of any adjoining garden and/or driveway may have raised to the point that it is now higher than the building’s DPC, thus rendering the damp proof course ineffective.
When the DPC is below ground level, this makes for easy entry for any moisture in the ground to rise through the walls without having to penetrate the DPC. The easiest way to fix this, assuming that no great damage has already been caused, is to reduce the property’s external ground levels so as it sits below the DPC.
Older buildings were built to breathe, with walls that easily allowed for moisture to travel from room to room without becoming trapped and forming mould spores on the surface. However, as time has gone on and properties have either been decorated or altered in a way that is not compatible with the needs of the building, this breathability can be lost and result in condensation or damp concerns.
One such cause is the use of insulation, with homeowners keen to keep as much heat in the property as possible to reduce energy costs. When an older property is fitted with insulation, there must still be a ventilation system in place such as an extractor fan. You will also be advised to keep doors and windows open as much as possible, particularly in wet rooms, to allow moisture in the air to travel freely, reducing the risk of condensation.
When it comes to eventually repairing and/or replacing any of the features on an older building, the correct materials must be used. Impervious materials that trap moisture, such as concrete, can worsen any damp problems in the property. It is often the case that older properties feature lime mortar which, as a porous and permeable material, allows the building to breathe and aids the property’s ventilation. If this is replaced with cement mortar, this effectively stops the building from breathing.
This is why any damp-proofing work must be conducted by a professional team with experience in the field, knowing exactly what it is they are looking at. Far too often older properties continue to suffer from issues relating to a damaged and/or faulty DPC and poor ventilation caused by the introduction of materials that are not compatible with its structure, resulting in costly repair works.
Here at Garratt’s Damp & Timber, we have close to 20 years of experience in diagnosing and treating various damp problems and are so confident in our ability, we offer a 20-year guarantee on all general damp proofing work carried out by our team.
For more information on the different types of damp problems in older buildings, as well as to arrange a property survey complete with a no-obligation quotation, please get in touch with us today.