Regular visitors will have noticed that we have had damp problems in the south wall for many years. In spite of annually scraping, filling and repainting it is a losing battle. Even the filler won’t stick for long, which is why we have chosen this year to repaint and not try to fill the craters.
When we did the exterior refurbishment in 2014 we hoped that by removing all the exterior cement render and replacing it with breathable lime render that the wall would dry out. One theory was that damp in the ground was trapped under the concrete floor slab and rose up the wall. Why the damp only occurred in one wall was a mystery. We recently removed the 1970’s wainscoting to do a damp meter survey and only then it became clear that it wasn’t rising damp.
There is a question over the ability of the external window cills to shed rain water, and the water soaks into the wall rather than running off. We have applied for Listed Building Consent to add lead flashing over the external cills, preserving the original but failed C18th brick cills underneath. The new lead will be painted to hopefully make it slightly less obvious. Our current thinking is that we should remove all the interior plaster on the south wall and replace with breathable lime plaster.
There is not much more we can do to protect the south wall from driving rain which, in the UK, is principally from the SW, or from the traffic spray. Once, the wall might have been coated with a hard cement impermeable render, but this method is now known to fail when the cement eventually cracks and allows water through. Modern heritage building advice is to let the walls become damp, but allow them to naturally dry out by using breathable render and paints. The OBS walls are solid and made of flint, so is likely that the wall will still take several years to dry out once we have lime render on both sides.
We have also applied for Listed Building Consent to install security grills and/or CCTV on the north side to protect the windows which have been pointlessly smashed on five different occasions in two years. Most importantly we want to ensure that building hirers are not at risk from further vandalism.
We still have to obtain formal agreement from several parties, such as West Berkshire Council and Thatcham Town Council, which is going to take several months. Then our Architects, Mathewson-Waters, will need to finalise a detailed specification and obtain contractors’ quotations which will take a further few months. While external work such as CCTV or window grill installation won’t inconvenience hirers, the south wall plastering will have to fit around hirers’ bookings. Realistically however, these works would be “sometime in 2019” at the earliest.
We should be able to fund this work out of our existing reserves but any donations or sponsorship would be gratefully received. The planned improvement works to the wc and kitchen will be dependent on finding new funding.
Mark Thomas, Vice Chairman, OBS Charity