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Insulating Older Homes

Insulation is a very effective way of saving energy, but you need to make sure it is properly installed so it doesn't cause other problems. Some types of work may need permission and you should seek advice, especially if your home is listed or in a conservation area (see Who Do I Contact?). 

Sheep's wool wall insulation being fitted
Sheep's wool has been added within the depth of the frame during the repair of this timber-framed building

Insulating roofs

Loft insulation

Adding insulation to your loft or attic is one of the easiest and cheapest ways of improving a building’s energy efficiency. Relatively thick layers of insulation will not cause problems if installed carefully. To meet current Building Regulations you will need about 300mm thickness of insulation.

Insulating pitched roofs at ceiling level

Roof insulation at rafter level

Insulation can be added above, between or beneath the sloping rafters. Insulation added above rafters, known as sarking insulation, can be very effective if installed in one continuous layer with no gaps.

The disadvantage of sarking insulation is that it will raise the roof slightly to accommodate the depth of the insulation used. This may mean having to adjust gutters, eaves, gables, ridges and abutments with chimneys, which can significantly add to the cost.

Adding insulation between and below rafters can usually be tackled from within the building. Although this may be a cheaper option, it will generally involve removing internal finishes, which may be a problem if these finishes are historically significant.

Insulating pitched roofs at rafter level

The following publications provide further useful information:

Close-up of a stack of wood-fibre insulation boards
Permeable insulation such as this wood-fibre board is compatible with the ‘breathable’ nature of traditional construction

Insulating floors

Adding insulation to suspended timber floors

Many traditionally constructed buildings have a timber ground floor suspended above a ventilated sub-floor. Insulation material is placed between the joists underneath the floorboards, so insulating suspended timber floors will require access to the floor void.

If the void is very shallow, which is often the case, all the floorboards will need to be lifted in order to add insulation. This can be a difficult job as it is very easy to damage old floorboards. It is sometimes possible if a building  has a basement or cellar  to add such insulation from below .

Insulating suspended timber floors

Insulating solid floors

Heat loss through solid floors is comparatively small compared with many other forms of heat loss. Insulating a solid floor usually requires excavation, which can be potentially damaging to historic floors.

And even where there is no historic value to the existing solid floor, any alterations to the floor structure need to be carefully considered. The amount of work required also means it's likely to be expensive and not particularly cost-effective.

Insulating solid ground floors

Insulating walls

Adding insulation to solid walls

A large proportion of traditionally constructed buildings were built using solid masonry walls, either of brick or stone, or sometimes a combination of the two.Though these materials look very different their thermal properties are quite similar. Masonry walls are not good insulators and often feel cold.Solid walls can be difficult to insulate for a number of reasons:

  • There is a danger of trapping moisture
  • Skirting boards, architraves and services will need to be removed and refixed
  • Adding insulation can reduce the floor area which, if the room is already small, could be a significant issue

Insulation can also be added to the outside of solid walls but in most cases this is likely to radically alter a building's appearance and character.

Insulating solid walls

Adding insulation to cavity walls

Modern cavity walls are easy and cheap to insulate but early cavity walls built before the 1930s can be more problematic as they are often very narrow or irregular.

All cavity walls should be surveyed prior to work being carried out to check that the cavity meets the necessary British Standard.

Insulating early cavity walls

Adding insulation to timber framed walls

With timber framed buildings it is important not to replace surviving historic panels, so insulation might have to be placed on the inside of the frame rather than within the depth of the timber frame itself.However, where inappropriate materials have been added between the frame, such as concrete block-work or cement render, there might be a good opportunity to replace these with 'breathable' insulated panels. In some cases where the frame is clad, for instance with weatherboarding, it may be possible to place insulation beneath the cladding.

Insulating timber framed walls

Insulation and Repair Work

If your home requires repair work to the roof, loft, floors or walls it's worth considering having insulation installed at the same time. This will be more cost-effective and, if you were considering installing it at some point anyway, can minimise any disruption.

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