Mark, what do you see as the main challenges of listed building projects?
Countering the unexpected is probably the most challenging aspect of dealing with projects on Listed buildings. Even with thorough investigation before construction coming across unsuspected defects, unusual materials or construction techniques, previous poor quality repairs or alterations and the potential for contamination or hazardous materials can all arise, which does make such work unpredictable but interesting. After all, practical problem solving is probably what draws a lot of people to the construction industry.
In your opinion, what are the principal factors which could delay a heritage building project and what is key to preventing these?
Prior to the commencement of construction the process of obtaining Planning and Listed Building Consents and, where applicable, obtaining grants or similar funding can result in delays, particularly where additional information is requested unexpectedly.
However, these frustrations can be minimised, or often eliminated, provided that sufficient time and care is taken in preparing the initial submissions. Key to this is having a clear understanding of what the project objectives are and how these can be implemented, whilst respecting and responding to the building’s historic character.
Where such approvals are required, a convincing case can only be submitted if it is evident that the proposals are based on a detailed understanding of the historic significance of the property and a sound technical understanding of the building’s construction and the materials used. Proposals can then respond to these features and demonstrate that the building is not being devalued in terms of its historic importance or otherwise put at risk by the proposals.
Unknown factors which might only come to light during construction can be far more problematic as delays and resultant contractual claims can arise whilst work is hindered by the need for unexpected repairs. Details of the design may have to be altered to take account of previously unknown original construction details. The key to minimising such risks is the investment in time and resources for a detailed survey of the building with non-destructive investigation of concealed areas where required. However, even such thorough preparation cannot guarantee that previously unknown defects or structurally unsound past repairs will not significantly impact upon an otherwise carefully prepared construction programme.
Which materials are the most challenging to work with on a heritage building project (and why)?
I don’t think you can generalise, as many materials pose significant challenges but these vary depending upon the individual building, how the materials have been used in the original construction and the quality of subsequent maintenance and repair.
A project which at first sight can appear relatively straight-forward can quickly become far more complex. An example of this was the repair of a number of prominent Coade Stone urns at Somerset House. Initially it was thought that only some superficial surface repairs were required but upon detailed examination it was found that they were in very poor condition, not only due to deterioration through exposure to the elements but that this initial damage had been greatly exacerbated by previous inappropriate repairs – ferrous cramps had been used to address some earlier cracking to the urns. Corrosion of these cramps had greatly increasing the damage – an example of a repair undertaken with good intentions but being poorly thought-through, thereby exacerbating the situation.
What are the main factors which affect the cost of a heritage building project?
Funding, revenue and operational limitations – in order to be successful, funding applications are often sought in a phased approach. This can also be influenced by the need to maintain an on-going operation and reduce revenue loss during the period of the works. This can result in works being fragmented and the overall period of construction being extended, resulting in reduced economies of scale and increased overhead and management costs.
The specialist and project-specific nature of the work can also be a factor. There is reduced opportunity to utilise standard building components (e.g. windows and doors) with design and specifications tending to be largely bespoke resulting in increased material supply prices, and higher supply and installation prices due to reduced competition in specialist areas of work.
Due to the inherent risk of opening up existing buildings and the discovery of unknown artefacts, features etc., coupled with the limitations of conservation and listed buildings, there is an enhanced risk of changes and additions to the scope of work. The risk of change is a much higher cost and can extend construction programmes arising from the works themselves and the potential for additional approvals being required.
What has been your most interesting experience working on a heritage building project (and why)?
The repair of a collapsed ceiling and associated supporting coffered ceiling to a small family chapel in rural Devon was particularly interesting, as although on a small scale it involved technically challenging repairs and the use of specialist contractors.
The need for repair was only revealed when a number of the panels were found to have collapsed into the chapel below and initially it was thought that the traditional plaster had simply separated from the lathes. However, a survey of the roof space above revealed extensive damage due to a combination of decay and infestation of the supporting timber structure, with a number of the principle timbers having been very heavily damaged, with little structural integrity remaining.
The decorative plaster panels themselves were also found to be losing their bonds with the supporting lathes. Temporary propping of the decorative plaster panels and structure were required to prevent further collapse and loss of historic material, whilst the full extent of the damage and a structurally sound but, aesthetically acceptable, repair solution was developed and agreed with the local authority conservation officer.
The feature ceiling was one of the key design features of the chapel interior and so the conservation officer agreed that repair and replacement should replicate the original designs as closely as possible using the original materials but to facilitate this a new steel supporting structure could be installed in the roof void from which the structurally damaged sections of the ceiling could be hung.
Specialist contractors were engaged to undertake repairs, including resin repairs, to the remaining timber structure, which in some instances comprised little more than a thin shell of sound material around a completely decayed beam; replacement of the destroyed plaster panels with hair-reinforced lime based plaster; and the others refixed to the lathes before redecoration and gilding.
Although one of the smallest projects I have worked upon, the intimacy of the space involved and the delicacy with which the remaining fragile structure had to be treated makes it one of the most interesting and memorable.
How can heritage building owners ensure that future requirements for repair and upgrade are kept to a minimum?
The key has to be regular and appropriate maintenance and repair. It is obviously temping to skimp on routine maintenance such as clearing gutters of debris and vegetation, or to reduce the frequency of external redecoration, particularly of timber features, but what might appear to be useful financial savings can quickly lead to deterioration of the property, often in areas that are not readily accessible and so the early signs of damage to the property may not be obvious.
It is sometimes surprising how robust historic buildings can be to this sort of neglect but this can mean that extensive damage can sometimes occur before the owner is aware that there is a problem and so relatively small savings in maintenance costs can result in considerable repair bills.
Another major issue is ensuring that appropriate advice is obtained once the need for repairs is identified and, that contractors experienced in the repair and maintenance of traditional buildings are used with a good level of site supervision. Without these precautions it is common for inappropriate repairs to be specified or for contractors to cut corners or alter a specification if they do not understand what effect this might have on a building constructed with traditional materials. Again, the temptation to refrain from seeking suitable professional guidance, or to accept the cheapest tender, can result in the need to renew faulty repairs in only a few years and these in themselves may result in further damage and higher associated costs.Back to top