Renovating a period property without fighting how it was built

Damp is the most misunderstood problem in older houses. Water coming in from outside through a leaking gutter, a cracked render, a raised flower bed or a garden path built up above the floor level is far more common than true rising damp. Condensation from modern living in rooms with blocked chimneys and sealed windows is another major cause.

Chemical damp-proof course injection and cement replastering are often sold as the cure. The Planning Portal notes that installing or replacing a damp-proof course does not in most cases need Building Regulations approval, which also means nobody checks whether it was needed. Ask for a diagnosis that looks at the outside first: gutters, downpipes, ground levels, pointing and render. An independent surveyor who does not sell treatments is worth the fee.

Suspended timber ground floors rest on joists over a void that is ventilated through airbricks in the outside walls. When airbricks are blocked by raised paths, extensions or rendered over, the void gets damp and joists rot. A renovation should clear and, if necessary, add airbricks, and any floor insulation fitted between the joists should keep the void ventilated.

Chimneys in older houses do two jobs: they carry smoke and they ventilate. A disused flue should be capped with ventilation at top and bottom, not sealed. Removing a chimney breast is structural work: whatever sits above has to be properly supported, Building Control has to approve it, and where the chimney is in a party wall, GOV.UK names removing it as work that requires notice under the Party Wall etc. Act 1996.

Source: legislation.gov.uk

Lath and plaster ceilings can often be repaired and re-fixed rather than pulled down, which keeps cornices and ceiling roses intact and avoids a huge amount of dust. Where ceilings must go, some owners replace them in lime to keep the look and the breathing performance. Original joinery such as doors, skirtings, architraves, staircases and shutters is usually better repaired than replaced; matching new work to old profiles is specialist, costly joinery.

Sash windows can be overhauled with new cords, repaired timber and draught-proofing, and secondary glazing adds warmth without losing the originals. If the house is listed, consent is needed for works affecting its character, and that includes interior features. In a conservation area, the exterior is what the council mainly controls.

Many period houses have been rewired once, decades ago, and replumbed in several stages. Old lead water pipes can still be found in some older properties; the water company can advise on the supply pipe and whether it is lead. Running new cables and pipes through old joists needs care, because deep notches weaken floors that are already under strain.

Heating an older house efficiently usually starts with draught-proofing, loft insulation and careful floor insulation, then looks at the walls with materials that let moisture escape. A heat pump can work in a period property, but the heat loss survey should come after these improvements.

Experience with period buildings shows in the questions a builder asks. Expect questions about lime, ventilation, what was done before and what should stay. Be wary of a firm that proposes to hack off all plaster, inject a damp course and tank the walls before seeing the outside of the house.

Specialist trades, such as lime plasterers, sash window joiners and leadworkers, may be subcontracted. Ask who they are and to see their work.

• the diagnosis of damp and its causes, not just the treatment
• materials: lime or other breathable mortars and plasters, where used
• features to be kept, repaired or replicated, room by room
• airbricks, subfloor ventilation and flue ventilation
• structural work to chimneys, beams or walls, with engineer's design
• consents needed: listed building consent, planning, Building Control

Describe the house, its age and what you have in mind. Renovation firms in your area see the description without your personal details, and only one can buy it; that firm pays Offrano, while the service is free for you. Before the firm sees who you are, we email you its name, address and phone number.

We cannot promise that a firm takes on the request, which is withdrawn after 21 days without a buyer, and you never have to accept a quote. Offrano checks only that the buyer is a registered business, not its experience with older houses. Ask to see period properties it has worked on.