“Maddisons appointment to undertake periodic inspections of the Borough’s corporate building stock has been one of the key elements to the Council’s successful planned maintenance programme. With structures dating back to 1630, and with a mixture of Scheduled Monument, Grade I and Grade 2* Listed Building status, few buildings can be more challenging for building surveyors than Guildford Museum” says Bill Gill, Estates Department, Guildford Borough Council.

During a periodic maintenance inspection the previous year the Maddisons surveyor noticed several splits and holes to leadwork coverings on the museum roof. Despite the lead having been replaced only 15 years ago we were concerned that it showed signs of premature failure and suggested further investigation.

Upon opening up the lead was found to have thinned to only microns in thickness in various places. This was due to excessive corrosion on the underside of the lead from condensation trapped below.

Maddisons were initially commissioned to undertake a measured survey of the building and to prepare detailed plans and elevations for the Council’s records. We were then appointed to prepare a specification and schedule of remedial works, to procure tenders and supervise the works on site.

The Museum is open to the public for six days a week and although most of the work was external some related internal repairs were also required. The ramifications of working in an occupied building, which is also a historic monument, placed many constraints on the building operations and project management of the works.
The principal requirement for management of this project was that the project had to be completed in a timely fashion prior to the opening of a new gallery. Close liaison was therefore required between English Heritage, the Planning Department and the Museum management. A further challenge was to ensure rigorous compliance with the health and safety plan due to the toxic material whilst maintaining commercial considerations and providing the technical solution.

The main technical issues related to the lead work where corrosion had created a white carbonate dust on the underside of the covering. This dust is highly toxic and it was essential that it was prevented from being dispersed into the air, inhaled, or ingested by persons within close proximity.

Careful risk assessment and a method statement for safe removal of the lead was therefore essential and to assist in this a regime of ‘air monitoring’ was adopted before, during and on completion of the works.

In addition to the lead replacement works a number of ancient timbers had to be repaired or receive preserving treatments. Whilst the roof was stripped it was discovered that air conditioning plant had been built into the void and whilst still live it had been redundant for many years. Their removal enabled a solution to be designed for cross-ventilation to the roof void.

The works were completed on time and within budget despite the additional plant removal works. Regrettably some six months after the works were completed the lead was stripped and stolen, and had to be renewed again, the cost of which on this occasion was recovered from the insurers.