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Interior Wall Insulation

Around half of all the heat lost from a typical solid-walled home escapes through the walls. Insulating these walls will keep the warmth inside for longer and greatly reduce your heating bills. Solid walls can be insulated internally (from the inside) and externally (from the outside) – both are significant undertakings in terms of cost and disruption.

Solid wall insulation may be suitable for homes made from brick, stone or concrete construction, and works by adding a layer of thermal material to the existing inside wall. This will reduce the size of your rooms a bit, though you may find if a cold wall is made warmer you actually increase the amount of usable space in a room.

Internal solid wall insulation is particularly appropriate where you need to maintain the external appearance of the building (e.g. in a heritage context).

How do I know if my home has solid walls?

If your home is made of brick, and the bricks have an alternating long-short-long pattern like this, then the walls are likely to be solid. If you can see only the long edge of the bricks, like this, then they are almost certainly cavity walls.

If the brickwork is not visible, measuring the thickness of the wall at any entrance or window will help to determine the construction type. A solid brick wall is usually about 22cm thick, a cavity wall between 27cm and 30cm and a solid stone wall as much as 50cm thick. The age of your home can also be a good indicator; if it was built before the late 1920s it is likely to have solid walls.

Adding insulation to the internal walls can mean replacing the woodwork around sash windows like these

Types of internal solid wall insulation

There are various ways to insulate a solid walled building from within, but they broadly fall into four categories:

1) Rigid insulation boards
These come in a variety of materials and thicknesses and deliver the highest energy saving. Some have pre-attached plasterboard which makes the installation process more straightforward.

2) Dry lining
Here, battens are fixed to the walls, insulation is fitted between them and then covered with plasterboard. This is a good option if the wall has a lot of heavy fittings such as book cases or kitchen cupboards, or if the original wall is rough and uneven, as in some stone properties.

3) Flexible thermal lining

This comes in rolls like thick wallpaper and is glued to the wall with a special adhesive. It may not provide the same level of insulation but can be installed by a competent DIYer. Flexible linings tend to be no more than 10mm thick so can be a good option for small rooms.

4) Insulated plaster
This is a mix of plaster and insulating material, such as cork. It is trowelled or sprayed on. It is a good option for uneven walls and can help achieve good levels of airtightness.

Managing Moisture

Most solid walls were built to be ‘vapour-open’ meaning that moisture can pass through the wall. If we insulate with ‘vapour-closed’ materials (such as foil-faced insulation foam) we risk trapping moisture inside the wall which could lead to damp, mould and damage to the building. If the existing wall is vapour-open you should always use vapour-open insulation materials, plasters and paints. Suitable insulation materials include woodfibre, mineral boards and cork. These should always be plastered with a lime-based finish and painted with vapour-open paints.

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Telephone: 0333 344 1542

Email: info@ecohomeuk.co.uk

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