Insulation

Insulation is key to making a home warmer and lowering bills, and from natural sheep’s wool to hi-tech materials, there are a range of options worth considering

Conserve heat and save energy with these insulation solutions

The right way to insulate old buildings has been much debated over the years. Most period homes were built in the days before cavity walls and modern insulating materials, and adding an extra layer can be a delicate balancing act – get it right, and you will be warm and comfortable, and benefit from lower energy bills; but get it wrong and your home could be damp from condensation, and you could even damage the building fabric.

Period homes are often thought of as being draughty, and air leakage is responsible for as much as a third of a building’s heat loss. While reducing draughts by sealing up gaps and adding seamless insulation layers is key to making a house feel warmer, in order to prevent condensation it’s important that materials are breathable and ideally able to help control humidity in the atmosphere.

Insulation products made of natural materials work especially well with old buildings. ‘Natural fibres are truly breathable and can help buffer humidity levels, holding moisture in a less harmful way,’ says Mark Lynn, managing director of Eden Renewable Innovations and a director of the Alliance for Sustainable Building Products. ‘This is particularly important in older homes, where ventilation and humidity levels may be problematic.’

Although natural products cost more than many mainstream options, they are renewable and can even help reduce the levels of indoor pollution. However, don’t overlook man-made insulations, as there are some extremely effective, breathable products that are suitable for period homes. Often the best solution is to employ a mix of materials – consult an expert with experience of old properties.

Where to insulate

Lofts: If your loft is not currently insulated, then tackling it should be your first priority – it’s the easiest area to insulate, and considering up to a quarter of an uninsulated home’s heat is lost through the roof, it’s an important one, too.

The most cost-effective solution is a ‘cold’ roof, where the insulation is laid on top of the ceilings of the rooms below. This is usually done by laying quilts or batts of insulation between and over the joists. Alternatively, loose-fill insulation, which fills all the gaps, can be used. It’s important to maintain ventilation paths at the edge of the roof to avoid condensation, which can rot the timbers.

If you want to convert the loft into living space, you will need a ‘warm’ roof, where the roof itself is insulated. If reroofing is taking place, you could insulate above the rafters, although this will raise the roof height. The other option is to insulate between or below the rafters, or a combination of both. A variety of materials can be used, but it’s important to maintain an air gap beneath the tiles. ➤

WALLS: It is estimated that 35 per cent of an uninsulated building’s heat can be lost through the walls, but this is disruptive to address. Homes built before 1920 had solid walls, as opposed to including a cavity that can be filled with insulation. Solid walls can be insulated either internally or externally – but both solutions involve covering the existing wall finish, which can mean the loss of period features. For internal walls, rigid insulation boards can be applied, or a stud wall constructed and filled with soft insulation. Plaster is then applied over the top. This inevitably affects existing skirting and cornicing. To insulate external walls, a layer of insulation is applied and covered with lime render or other cladding. This can totally change the look of a house and affect elements such as overhangs, windowsills and door openings, so is not suitable for the beautiful façades of many period homes. floors: Around 10 per cent of a property’s heat is lost through floors, of which there are two types: solid or suspended timber. Solid floors are in direct contact with the ground, so without lifting them it is difficult to add insulation, but topping them with breathable, natural carpets, such as coir, will help. Avoid rubber-backed designs. If the original floor has previously been replaced with concrete and includes a damp-proof membrane, then laying a floating wood floor on top can improve thermal performance. If there are damp problems with a concrete floor, consider replacing it with limecrete, made of breathable lime and aggregate.

Suspended floors are straightforward to insulate where there is access from below, such as a cellar. Quilt-type insulation can be fitted between the joists, supported with netting. Insulating from above involves lifting floorboards, so think twice if the floor is of historical value. If you do disturb the boards, lift a small number at a time. A variety of soft insulating materials can be used, supported by nets, or rigid materials can rest on timber battens.

Draughtproofing.

Alongside insulating, it’s important to address gaps, as heat is easily lost through them. The Energy Saving Trust estimates that simply filling gaps can save up to £40 per room, per year on bills. Open chimneys are easy to block off with an inflatable Chimney Balloon or removable Chimney Sheep, while gaps between floorboards can be sealed with discreet strips, such as Stopgap or Draughtex.

Narrow gaps around windows and doors can create draughts as well as rattling noises. Avoid silicone sealants and instead use draught strips, which can be removed in the future if required. If you have single-glazed windows that make a room feel cold, look at fitting secondary glazing.