A. Be very careful about the diagnosis of damp. Moisture entering a wall at higher levels often descends down the wall and accumulates at the base, leading to many false diagnoses of 'rising' damp. Ask an independent specialist (someone who does not have a vested interest in selling a treatment) to determine the source of the damp, and give advice on how to rectify it. Even if the source of the damp is groundwater, it is very difficult to effectively retrofit a damp proof course into a solid wall. It is important to be absolutely sure that the source of the damp has been removed before attempting to insulate the wall.
A. There is no single figure that would be a good guide for all buildings. A great deal of the cost of installing wall insulation is in the cost of the adjustments that have to be made to accommodate it: changes in rainwater goods, eaves, verges, and window surrounds etc for external insulation and to cornices, skirting boards, wiring and plumbing for internal insulation. These will all vary dramatically from building to building. Meanwhile the benefits will also vary as the size, shape and construction of older buildings varies so much. Before embarking on a significant improvement such as wall insulation it is a good idea to instruct a building services engineer to run the proposal through a computer programme which can model the thermal performance of the building. The benefits of the insulation can then be predicted.
A. It is very important that all materials used to insulate walls of traditional buildings are compatible with the breathing performance of the wall. Wood-fibre based boards can be used for internal or external wall insulation. Finishing coats of render can be clay or lime based. If you are insulating internally with a dry-lining system a range of fibrous insulation materials can be used between the studwork.
A. Different insulation materials have different properties so it’s always worth checking with the manufacturer or supplier if you have a target standard you wish to meet. Also the Building Regulations change from time to time (and are different in the different countries of the UK), so it is worth checking the current regulations. The thickness of the existing wall will also affect the amount of insulation needed to meet the current building regulation targets.
For most traditional and historic buildings, however, the decision of how much insulation to install will be driven by the practicalities of the building. Building Regulations only require what is practically and economically feasible.
A. No. The Building Regulations only apply to new building work, so there is no need to upgrade an existing wall to meet the standards if you are not doing work to it. However, if you are refurbishing a wall, for instance by removing render or plaster from it, then you should take advice from a building control surveyor on what is required.
A. Almost certainly, but do check with your local planning authority’s conservation officer as every building is different. With listed buildings, consent will be required for any alterations, external or internal, that affect the appearance and character, including any materials, details and finishes of historic or architectural interest.
A. Check with your local planning authority’s conservation officer as rules vary from area to area. Purely internal work is unlikely to require permission, but external insulation would require planning permission which would be unlikely to be granted in most conservation areas.
Back to top