An important note: Structural waterproofing work must not be progressed within a listed building, without obtaining listed building consent from the Local Authority.
Be assured that Trace is perfectly placed to advise on all options for conservation waterproofing to all types of historic and listed buildings throughout the UK and Europe.
In our 47+ year history, we’ve successfully completed structural waterproofing projects on over 570 Grade I, Grade II* and Grade II historic and listed buildings.
With many historic and listed buildings not benefiting from modern forms of protection, they are often subject to the detrimental effects of damp. The challenge when dealing with buildings of special architectural or historic interest is to maintain structural and aesthetic integrity, whilst still achieving the desired effect.
The interesting aspect of effectively managing listed building (conservation) waterproofing is the extent of conflict between the advice that would normally be followed (compliance with British Standard 8102) and conservation preferences.
When treating damp in historic and listed buildings, it is important that any products meet with the stringent Listed Building Requirements. Many products normally require surface preparation techniques that are unacceptable due to the detrimental effect on the structure, which are often irreversible.
However, some products, such as damp proofing membranes, can still be applied with little preparation and minimal fixings. Once installed, the membrane provides an impervious barrier between the damp surface and the new internal wall, preventing moisture and moisture vapour from affecting internal finishes. When supplemented by drainage, this is one of the most effective forms of protection.
For the purpose of this page, we´re principally considering habitable use, because it is both a typical use of space and implies comprehensive systems, so best illustrates the opposing positions of BS8102 and conservation principles, but if the space isn’t to become habitable, this influences the available options. Please enquire for more information.
If it is habitable, then a balanced solution needs to be designed and applied; achieving suitable conditions for the intended use, without wholly covering up the structure, meanwhile ensuring the critical appearance and features are preserved.
Part of the listed building consent submitted to the Local Authority may be a condition survey to record where and how damp a space is, also with consideration of any contributory causes. Trace can assess and report on this basis also.
In the 21st century, the need to either waterproof or install a waterproofing system to Georgian and Victorian basements and other sub-ground spaces within the building is increasing with the changing use of basements and the end user requirements.
Prior to the twentieth century, basements were commonly used as servants` quarters, storage rooms or kitchens. These areas were often built in the same way because of the need to dig deep footings or foundations. These spaces were kept dry with partially effective drainage systems, which after more than a century in the ground have now become unserviceable. They are often filled with silt with the masonry damaged by ground water movement and poor external landscaping.
Minto & Turner Listed Building, Manchester - basement waterproofing completed by Trace
BS8102 code of practice for protection of below ground structures against water from the ground, in many respects advises you to design for the worst case scenario.
The implication therefore is to design and install comprehensive waterproofing to all wall and floor surfaces, ensuring that a dry space, completely free of dampness, is provided in the long term.
This is sensible from a pure waterproofing risk perspective, because what you do not want as a building owner, is to invest significantly in making a space liveable (fixtures, fittings and finishes), for that to become damp, and you then have to strip out and retrofit waterproofing.
However, treating all walls and floors implies covering the structure and in this the appearance of the space is changed. It is this which conflicts with conservation of the space. Conservation by definition is ‘protection from change’.
It’s important to take a holistic view, assuming that pressure will come to bear as with point 1 above, and irrespective of any other factor: this is prudent but it shouldn’t be to the exclusion of all other factors. If there is an issue of water ingress (there often is) then what about the rate of surface water infiltration (rain getting into the ground), and can this be influenced?
Penetrating damp should be treated externally at the source of the water entry. Water in its liquid state can only pass through a wall if there are defects large enough to accommodate it, so it is these defects that require repair.
Many old walls were designed to be dampened by wind-driven rain with the expectation that they would dry out before any moisture reached the internal surface. However, persistent rain over many years means that this can and does happen, and shows as penetrating damp.
The solution is specially formulated external treatments, which penetrate into the wall materials, block the capillaries and prevent moisture from entering. Breathability also allows residual moisture to exit, resulting in damp-free internal walls that are dryer, warmer, and have a dramatically reduced probability of internal condensation.
Subterranean areas will always be subject to penetrating damp due to the natural watercourses within permeable soil, which channel the water like pipes. Saturated soil develops a head of pressure surrounding the subterranean structure, leading to water ingress through gaps and joints in the construction. Habitable or usable below ground areas therefore need to be waterproofed.
For historic and listed buildings, cavity drainage systems are ideally suited for this application. When installed by qualified contractors, the systems depressurise and collect water that enters the structure, before removing it safely. Internal finishes are isolated from the water, leaving a dry and habitable space for the occupier even in the most demanding situations.
Do you know if surface water drains are introducing water into the ground which is then accessing the basement of your building? This consideration applies to all basements, but is especially important in respect of our historic and listed building stock and as such must inform an historic and listed building waterproofing process.
