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Solid wall insulation – external

Nearly half of all the heat lost from some solid-walled houses (those without a wall cavity) escapes through the walls. Insulating these walls keeps the warmth at home for longer and makes homes more comfortable and cheaper to heat.

Solid wall insulation may be suitable for a variety of wall types such as brick, stone, steel-framed and concrete construction. And, depending on the circumstances, the walls can be insulated internally (from the inside) and externally (from the outside); both are significant undertakings in terms of cost and disruption.

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 the wall is almost certainly a cavity wall. If you can’t see the pattern of the brick work then 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 22 cm thick, a cavity wall between 27 cm and 30 cm thick, and a solid stone wall could be as much as 50 cm. The age of your home can also be a good indicator. As a general rule, if it was built before the late 1920s it is unlikely to have a cavity.

What does external wall insulation involve?

External solid wall insulation involves adding a layer of insulating material to the outside walls of a building and coating this with a protective render or cladding. There are lots of options to create the finish that you want and these may even add value to your home. External solid wall insulation, rather than internal, may be particularly suitable if you want to avoid any loss of space or the disruption of work going on inside your house, or if you are doing other work to the exterior of your property, such as re-rendering. It is a specialist job that requires an approved installer who will specialise in work using a specific insulation system.

Changes to the external appearance

External solid wall insulation won’t affect the size of your rooms  but you might need planning permission as it could change the appearance of the building. There is a wide range of colours and finishes that can be applied and all the options should be discussed with your chosen contractor. Often the existing finish can be replicated to preserve much of the original appearance of the house. As solid wall insulation is now constituted as an ‘improvement’ rather than an ‘enlargement’ you are unlikely to need planning permission. Consent and planning permission are likely to be required if your house is listed or is located in a National Park, area of outstanding natural beauty, conservation area or within a World Heritage Site. If you have any doubts at all then check with your local authority before you have any work done.

Average costs and savings

Externally insulating your home costs on average £5,000-£14,000, though this depends on the size of the building and the number of outside walls being insulated (a terraced house is cheaper to insulate). It is likely to be more expensive than internal wall insulation because of the cost of material and labour are higher. A typical 3-bedroom semi-detached house using gas heating could save around £235 per year on heating bills by installing external wall insulation whereas a detached house heating with oil could save around £480 per year.


External solid wall insulation is a significant undertaking that inevitably involves a degree of disruption. Your installer should make you aware of any particular issues but things to consider include:

  • Garden access may be required and boundary walls and lean-to structures may need to be adapted or removed
  • Scaffolding may need to be erected, and a space found for a skip and storage space for materials
  • External fittings like rainwater pipes, satellite dishes and telephone and power cables may need to be removed and replaced afterwards
  • Contractors will require water and power and the use of a toilet
  • There will be a lot of noise, including power tools, and the work will generate a lot of dust and dirt.

A cut-away model of external solid wall insulation

1 | Insulation board (next to brickwork) external solid wall insulation This is the layer of insulation that will slow the lost of heat from inside the house. It is attached to the external wall, either with an adhesive or mechanical fixings and protects and extends the life of your brickwork. 2 | Middle section (grey and mesh) This section, composed of a mesh between two thin layers of render, adds strength and rigidity. 3 | Top layer (white on this diagram) A final coating of cladding or render is applied to give the wall the required appearance. It brings the total thickness of the added material to between 50 and 125 mm. 4 | Window sill External fittings such as pipework and satellite dishes may need to be removed before insulation is applied. It may be necessary to remove and extend window sills so they protrude beyond the cladding 5 | Window and frame Windows can change in appearance, as the insulation needs to extend into the window recess.





The company offers hundreds of products, including technological systems composed of many complementary products. The most important product groups include: materials for laying ceramic and stone tiles, priming, cleaning and protecting materials; ready-to-use mortars, insulating materials and sealants, enhanced renders and façade paints, thermal insulation systems, floors and self-levelling screeds, and a wide range of gypsum products.

Managing a company is in line with world standards. Integrated Management System consists of three complementary subsystems: the quality management (ISO 9001:2008), environmental management (ISO 14001:2004 + Cor 1:2009) and the management of occupational health and safety (BS OHSAS 18001:2007).

SYSTEM ATLAS (ETICS) Composite thermal insulation system with render coatings the first Polish system, which received European Technical Approval according to ETAG 004:2000 system with foamed polystyrene boards Properties: gives required thermal insulation parameters to walls protects and increases fastness of external walls wide range of textures and palette of colours for renders and paints increases aesthetic value of facades SYSTEM ATLAS (ETICS)

ATLAS XPS SYSTEM External thermal insulation composite system with rendering The concept of the system is based on the use of extruded polystyrene (XPS) panels as the thermal insulation material- it conforms with a European Technical Approval ETA-07/0316, issued on the basis of the Guideline for European Technical Approval included in ETAG 004: 2000 Properties -creates required insulation of external walls -increases durability of external walls – the system is resistant to mechanical impacts, moisture and impact of microorganisms

External thermal insulation composite system with rendering

ATLAS ROKER SYSTEM External thermal insulation composite system with mineral wool boards recommended for thermal insulation of different types of buildings, demanded for tall buildings above 25 m high. Properties increases fire protection of building construction elements, highly vapour permeable, increases acoustic insulation, facilitates insulation of protruding surfaces, new quality approved by European Technical Approval ETA -06/0173

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Types of internal solid wall insulation

There are various ways to insulate a solid walled building from within, but they broadly fall into three 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 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 using a special adhesive. Flexible linings may not provide the same level of insulation but you could install the material yourself if you are a competent DIYer. Moreover, as flexible linings tend to be no more than 10mm thick they can be a good option for rooms that have limited space.

Average cost and savings

Internally insulating your home will probably cost between £5,500 and £8,500, depending on how many rooms are being renovated and the type of material being used. Generally this is less expensive than external solid wall insulation because of the lower cost of materials and labour. A typical 3-bedroom semi-detached house using gas heating could save around £260 per year on heating bills by installing internal wall insulation whereas a detached house heating with oil could save around £450 per year.


Internal solid wall insulation is a significant undertaking that inevitably involves a degree of disruption. Your installer should make you aware of any particular issues but things to consider include:

  • A skip may be required
  • Rooms where the work is being done may not be usable whilst the work is being carried out and furniture, kitchen units etc may need to be temporarily removed
  • Fittings such as radiators, skirting boards, window sills and plug sockets that are on the wall that is being insulated will need to be removed and reattached afterwards
  • Pipe work and wiring may need to be re-laid
  • The works will produce dust and could be noisy at times
  • Contractors will require water and power, and the use of a toilet
  • The newly insulated walls and adjacent surfaces will need to be re-decorated when the work has finished.

Internally insulating a wall will reduce the size of your room. However, by making a cold wall warmer you may find you have more usable space.

A cut-away model of internal solid wall insulation.internal solid wall insulation

1 | Surface coating (green) This is the new plasterwork that covers the insulation layer. Just like a normal internal wall, it can be painted (green in this case) or papered                                                                                      2 | Insulation (orange) This is the layer that prevents warmth escaping through the outside walls of the house. In this case, rigid insulation boards have been used.                                                                                        3 |Internal wall (white) This is the old internal plaster which is now covered by the new insulation board and plasterwork.                                                                                                                                                                               4 |Windows Ideally, the insulation board is fitted to the inside of the window recess to prevent cold patches developing where condensation forms. But, as is the case here, this is not always possible.                                                                                                                                                                                      5 |External wall (brickwork) From the outside, your property will look exactly the same                                                                                                                                                                              .

Insulate your loft

Around 25% of the total heat loss for a typical home is through the roof. Insulating your loft can be a simple and effective way to reduce heat loss, keeping you warmer in the winter and saving you money on your energy bills.

What type of insulation material should I use?

The most common form of loft insulation is mineral fibre which comes in rolls that are laid out at the floor level of the loft between the joists. Loft insulation can also be made from sheep wool, hemp fibre, flax, cellulose or recycled materials like plastic, glass or newspaper. There are other alternatives such as rigid boards, blankets (where insulation is sealed inside a foil bag) and foam panels that squeeze between joists. Some materials are better insulators than others. So you could use a thinner layer of a solid insulation board to achieve the same results as a thick layer of mineral fibre, for example.

For this guide, we’ll assume that you’re using standard mineral fibre insulation. If you want to compare materials, you can use the figures on the product packaging or get the figures from manufacturers. Some retailers provide leaflets comparing the relative properties of different materials. Look out for:

R-value (the higher the better; a measure of how heat loss is reduced by a material)

k-value (the lower the better; a measure of heat flow through a material)

U-value (the lower the better; a measure of heat flow through a given thickness of a material)

Ventilation and condensation

Once the loft is fully insulated, the air temperature in the loft will be considerably cooler. Because cold air cannot hold as much moisture as warm air, condensation is more likely to form. To prevent condensation creating a damp problem, it’s important to make sure the loft is adequately ventilated and that air can circulate. Be careful not to cover air vents, and make sure that the insulation is not pressed up around the outside walls or eaves. Check the loft from time to time to spot any condensation problems. You may find additional ventilation is required. If you are concerned about condensation making items stored in the loft damp, consider using plastic boxes with fitted lids.


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