How to Approach Damp in a Listed Building
4 December 2018
A listed building is a building that holds significant architectural or historic national importance. Listed buildings are also included on one of the four statutory lists of ‘buildings of special architectural or historic interest’. The four lists cover all parts of the UK and are made up of Historic England (England), Historic Environment Scotland (Scotland), Cadw (Wales) and the Northern Ireland Environment Agency (Northern Ireland). Listed buildings come in all shapes and sizes, from terrace houses to large castles and from Lands End to John O Groats, listed buildings are literally scattered all over the United Kingdom.
So, what does it mean if a building is listed? Listed buildings benefit from having extra legal protection within the planning system above and beyond that of normal properties. There are three categories of listed building that are used in the UK, and these are based on their significance and importance:
Grade I buildings – To obtain this status the building has to be of exceptional interest. Only 2.5% of all listed buildings are Grade I
Grade II* buildings – This grade refers to buildings that are of particular importance and are of special interest. 5.5% of all listed buildings are Grade II*
Grade II buildings – Buildings obtaining Grade II status are of special interest. 92% of all listed buildings meet Grade II classification.
What parts of a building are covered by the grading?
The listing ordinarily covers the whole building, which includes all of the interior, unless sections of the property are excluded) The listing will usually cover the following:
– Any object or structure that is fixed to the building;
– Any object or structure within the the land surrounding the building. Although the object may not be physically attached to the building it forms part of the land and has done so since before 1st July 1948.
As all buildings are different, what is actually covered by a listing can vary quite widely from building to building. It is therefore prudent to check with the Local Planning department to identify what exactly is covered by the listing before commencing any work.
There are around 500,000 listed buildings in England, but it is difficult to be precise, because one listing for example can cover a row of terraced houses.
The main challenge that has to be faced when protecting a listed building from damp, or designing a basement waterproofing solution, it’s imperative to adhere to the “Listed Building Regulations Act 1990” in order to protect the structural integrity of a building with so much historic interest.
What is causing the damp?
There are three types of damp, rising damp, penetrating damp and condensation, these are all caused by various factors. Poor servicing of the property, poor build quality and design deficiencies within the property all have a part to play, especially within listed buildings where the design and build of the times would not meet modern standards.
What are the consequences?
Often such problems can go unnoticed for years and gradually the damage escalates. Regular checks can avoid such problems, particularly for vulnerable areas such as downpipes and hidden gutters. Damp can give rise to timber decay and insect attack when timber becomes very damp, with a moisture content of around 20%, it can attract insects such as wood-boring beetles and also can lead to dry rot and wet rot. Where the problem is left undetected for a long period, it can cause serious structural damage.
What are your options?
The recommended solution can in no way affect the integrity of the building and as such chemical solutions are not an option.
- A low-profile membrane can be placed on the walls with an integral mesh, this is applied with little or no preparation at all and depending on the chosen wall finish, only very few fixings are needed to hold the membrane in place.
- Electro-osmosis involves the introduction of a low static electrical charge into the masonry, via a series of titanium wire anodes. It is chemical free and environmentally friendly.
Timberwise have provided damp solutions, to both domestic and commercial, listed properties including University of Manchester’s Waterloo Place building, their iconic Grade 2 listed building forming part of the original campus and home to the University’s occupational health service
This Grade 2 listed building’s rear elevation downspout from the gutter was not sealed and fixed correctly, this was allowing moisture to enter the building instead of being dispersed away as required. The mastic seals around the windows were in poor condition and therefore allowing water to trickle through.
Timberwise advised the wall would eventually dry out and some of the current problems being experienced will naturally cure themselves once the walls are fully dried. In the meantime, the University needed a temporary measure to make the wall presentable.
Timberwise then proceeded to remove the surface plaster and a low-profile membrane was then placed on the wall with an integral mesh, a lime-based plaster was then applied which meant that in the future, possibly after 12 months, Timberwise would then re-inspect the property and if the walls have had indeed dried out naturally, as expected, Timberwise would then remove the temporary plaster and membrane and re-apply a traditional lime-based plaster to put the wall back into original condition without having affected the original integrity and structure of the building.
The System was quick to install and sympathetic to the structure, making it the ideal waterproofing solution all whilst retaining the original features of this historic property, thus meeting Listed Building Requirements.