Why Older Homes Need a Different Approach

Period properties were built to manage moisture, not to be airtight. Solid brick or stone walls, lime mortar and plaster, suspended timber floors and open chimneys all allowed water vapour to move through the fabric and escape. Modern materials work on the opposite principle: they seal, block and trap. That is why slapping cement render, gypsum plaster or foil-backed insulation onto an old wall so often ends in damp patches, blown plaster and rotten joist ends a few winters later.

The guiding rule is simple: keep the building breathable. Use vapour-permeable materials and let walls dry inwards and outwards as they always have. Retrofit is not about making a Victorian terrace behave like a new-build; it is about improving comfort and cutting bills while leaving the building able to look after itself.

Begin with the Cheap, Invisible Wins

Before spending money on walls, deal with the losses you cannot see. Draughts, not insulation, are often the biggest single source of discomfort in an old house.

• Chimneys: an open flue can pull warm air out of a room all day. Fit a chimney balloon or sheep's wool draught excluder in unused flues — but keep one flue ventilated if it serves a boiler or stove.
• Suspended timber floors: draughts whistle up between the boards. Lift a few boards and lay breathable insulation, such as sheep's wool or wood fibre, between the joists, leaving a clear gap beneath for ventilation.
• Lofts: top up to 270–300mm with a breathable mineral or natural fibre, keeping the eaves ventilation path clear and never blocking the gap at the wall plate.
• Doors and windows: brush seals, compression strips and a well-fitted letterbox flap cost very little and make an immediate difference.

Insulating Walls Without Losing Character

Solid walls are the hard part. External insulation will change the look of a period facade and may need consent in a conservation area or on a listed building, so most owners look inwards. Internal insulation works, but only with the right build-up and careful detailing.

A typical breathable internal system uses a stud frame or direct-fix battens, wood fibre or calcium silicate boards, and a lime or clay finish. Wood fibre at 60–100mm will noticeably improve a room's warmth without sealing the wall. Crucially, do not use foil-backed plasterboard, cement-based renders or injected foam in older solid walls — these trap moisture against the masonry.

Three details matter more than the insulation itself:

• Insulate the reveals and returns at windows and doors, or you create a cold bridge right where condensation forms.
• Keep the original plaster on the external face wherever possible, and repair with lime rather than gypsum.
• Never insulate a wall that is already wet. Fix the leak, the blocked gutter or the raised ground level first, then wait for the wall to dry out.

Windows, Shutters and Original Joinery

Original sash windows are usually worth keeping. Well-maintained timber with a decent draught seal and secondary glazing performs respectably, and repairs are almost always cheaper than replacements. Secondary glazing fitted on the room side, leaving a ventilated gap, cuts noise and heat loss while leaving the external profile untouched.

Where there are shutters, use them — closing internal shutters at dusk adds a real layer of insulation. Heavy curtains, lined and fitted close to the wall, do the same. If a window is beyond saving, replace like for like in timber, and check whether the property sits in a conservation area before ordering anything.

Heating: Right-Size, Then Improve the Emitters

Old houses rarely need a bigger boiler; they need a better-matched system. If you are considering a heat pump, the priority is reducing heat demand first, then making sure the emitters can run at lower flow temperatures.

• Room-by-room heat loss calculation before any boiler or heat pump is specified. Oversized systems cycle inefficiently; undersized ones never get comfortable.
• Upgrade radiators, particularly in living rooms and hallways. Larger, well-placed emitters let you run at 45–50°C rather than 70°C, which suits heat pumps and condensing boilers alike.
• Zoning and controls: thermostatic radiator valves, a smart programmer and separate upstairs and downstairs zones stop you heating empty rooms.
• Keep pipework warm: insulate all accessible primary pipework and the hot water cylinder to at least 80mm.

If you have an open fire or stove, remember that a chimney is a permanent hole in your insulation. Fit a register plate and a properly sized flue liner, and close the damper when not in use.

Ventilation and Moisture: The Non-Negotiable Bit

Every improvement that reduces draughts also reduces the air changes that were quietly drying your house. Cooking, showering and breathing add several litres of water vapour a day, and it has to go somewhere. Continuous extract fans in kitchens and bathrooms, trickle vents where windows are replaced, and a humidity monitor in a bedroom or hallway are sensible, low-cost insurance. If you are sealing a house tightly, a whole-house ventilation system with heat recovery may be worth discussing with a designer.

Work room by room, monitor for damp after each change, and be patient. A thoughtfully retrofitted period home can be warm, quiet and inexpensive to run — without sanding away the very details that made you fall in love with it.