Government Backed Scheme 
Around 7 million homes in the UK are built of solid wall construction - that’s 28% of all homes according to the National Energy Federation. Generally, houses that were built before the 1920s will have solid walls and probably don’t automatically have internal wall insulation. 
But that doesn’t mean they can’t be insulated; they can be. Approximately half the heat in a solid house is lost through the walls, so insulating the external solid walls will significantly lessen the amount of heat lost, making your home more energy efficient and reducing heating bills. 
 

Solid walls or cavity walls? 

As a rule, if your home was constructed before the 1920s and is brick-built, it is more than likely the external walls are solid rather than cavity walls. Solid walls are not as thick as cavity walls, although the walls of stone built homes are much thicker and timber or steel-framed houses are entirely different again. Measuring the thickness of your external walls in a window or external doorway will give you a good idea whether they are solid walls or cavity walls. 
 
In addition, if the bricks on the outside have an alternating pattern, i.e. one long brick, one short brick, one long brick, etc., they are probably solid walls. Houses built of brick that have cavity walls have a different pattern in that only the long edge of the brick is used. 
 
A solid brick wall is approximately 22cm in thickness, whilst a cavity wall ranges from 27cm to 30cm. Solid stone walls can be as much as 50cm thick. 
 
If your home has cavity walls, i.e. there is a gap between the external and the internal wall, and was built before the 1990s, it may or may not have insulation. Cavity walls are made up of two layers and the gap in the middle is where the insulation sits. Houses built from the 1990s with cavity walls will be insulated as this became an official building requirement at this time. 
 

Types of solid wall internal insulation 

Whenever internal solid walls are insulated, before you start it is important to realise that a small amount of floor space will be lost and it will be disruptive, but it can be carried out room by room. There are four general solid wall insulation categories
 
1. Rigid insulation boards – available in a variety of thickness and materials, rigid insulation boards provide the best level of energy saving. Some types come with a pre-attached plasterboard that helps to simplify the insulation process. 
 
2. Dry lining – with this option, installers will fix battens to the solid walls and then insert an insulation material between them, which is subsequently covered with plasterboard. If your home has a variety of fixtures to the walls that are heavy, such as kitchen cupboards, bookshelves or other items, or if the original wall is uneven, i.e. they are stone walls, dry lining is a good option. 
 
3. Flexible thermal lining – this insulation is available in rolls. Using a specially-designed adhesive, the insulation is glued to the wall. However, flexible thermal linings are usually 10mm in thickness or less and don’t provide as high a level of insulation as other options, but for small rooms they are a good option. 
 
4. Insulated plaster – this option uses a mixture of an insulating material, such as cork, and plaster which is either sprayed on to the solid wall or plastered to the wall using a traditional trowel. If the solid walls are uneven, such as in stone walled homes, this option is a good choice and helps in getting the insulation air-tight. 
 
When it comes to cavity walls, there are generally three types of commonly-used materials
 
1. Mineral wool or Rockwool – usually used in residential homes, mineral wool, also known as Rockwool, comes from igneous rock which is heated and then spun. This creates a fibre-like material which is blown into the space between the exterior and interior walls. It is resistant to water and prevents moisture from the outside elements permeating the walls. 
 
2. Polystyrene bead – known as Expanded Polystyrene Beads (EPS), the beads and an adhesive are pushed into the space between the two cavity walls. The adhesive holds the beads together so they don’t spill out from the wall. If the space between the cavity walls is narrower than standard, or if it is a stone build house, this is a preferred form of insulation. 
 
3. Cavity foam insulation – commonly used for insulating cavity walls is urea formaldehyde foam, although today polyurethane foam is a preferred choice. It is popular because to insert it into the space between the cavity walls, only a small hole needs to be drilled in the wall, or brickwork. 
 

Advantages and disadvantages 

There are advantages and disadvantages to installing internal wall insulation. Whether you have solid walls, cavity walls, stone walls, timber or steel, insulating your home will: 
 
● Save energy 
● Reduce your heating bill 
● Lower your carbon footprint 
● Retain heat within the home for more comfort 
● Act as a noise barrier to neighbours and outside elements 
● Potentially increase the value of the house. 
 
The Energy Saving Trust estimate that households can save as much as £460 for a detached house, £270 for a semi-detached house and £180 for a mid-terrace house on their heating bills over a period of a year. 
 
But there is a downside to installing internal wall insulation. With solid walls, the disadvantages include: 
 
● It is disruptive to family living and when a room is being insulated, it can’t be used 
● It creates a lot of mess and dust, and a skip may well be required 
● A small amount of floor space will be lost so if the room is small in the first place, it will be a bit smaller when the installation is complete 
● You need to make sure a porous insulation material is used if the solid walls are permeable, so that the walls can breathe, or add a vapour barrier to prevent damp. 
● Cold areas can be created so avoid this by making sure the insulation is continuous throughout, including at wall-floor junctions, internal wall-external wall junctions, and between walls. 
 

Available grants to help with internal wall insulation 

One of the main reasons why homeowners put off insulating their internal walls is due to the cost. However, there are a variety of government-backed grants available that can help towards the cost of installing internal wall insulation. 
 
The Energy Company Obligation (ECO) scheme is an incentive from the government which aims to make homes in the UK more energy efficient, as well as reducing the cost of heating homes. The grants also help towards lowering carbon emissions as well as fuel poverty among low income families. The scheme legally requires the principal energy suppliers in the UK to install energy efficient initiatives, including insulation and boilers, to homes in the UK. 
 
Cavity wall insulation grants are available for homeowners that qualify and will help towards the cost of insulating your home to reduce the loss of heat, as well as making your home more energy efficient. For more information on cavity wall insulation grants and to find out if you qualify for a grant, contact us
 
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