It is a little known fact the majority of heat loss occurs in buildings that have little or no wall insulation. In the worst instances this can account for 35% of heat loss in a property. Adding insulation to a building improves its ability to retain heat and reduces the amount of energy that gets wasted through heat loss to the outside air. For this reason, addressing the thermal effectiveness of walls should be a top priority for any property owner.
In addition to cheaper fuel bills, installing insulation will make your property instantly warmer and more comfortable. The building will be able to retain heat for much longer, which means that you will not need to have your heating on nearly as much to achieve a comfortable temperature.
Whilst this obviously means you can enjoy a significant saving on your heating bill, you will also be making a big reduction to your carbon footprint.
Furthermore, few people also realise that insulation of any kind helps to maintain the internal temperature of a property, so whilst this will keep inhabitants warmer during the colder months, it will also help to keep the temperature cooler during the summer.
There are a variety of different options available depending on the age and style of the building.
The most effective type of wall insulation can depend on the amount of space available both inside and outside the building, as well as the budget of the property owner and the existing thermal efficiency of the property.
Let’s take a look at some of the most common types of wall insulation that are available.
Cavity Wall Insulation
This is used for properties where there is a gap (a ‘cavity’) between two layers of bricks that for an outer wall. Buildings built after the 1920s have typically been constructed with cavity walls.
You can identify whether your property has a cavity by looking at the brick work. If the bricks are arranged evenly then it is likely to be a cavity wall. Cavity walls have the stretcher-brick configuration whereas solid walls tend to have the stretcher-header-stretcher brick pattern.
If the external brick-work is not visible, you can measure the depth of an external wall. If it is greater than 260mm then it is almost certainly a cavity wall.
If you have identified that your property has cavity walls, you can request an installer to carry out a borescope survey, which will determine whether there is any insulation in the walls already, and if so, how much.
Cavity Wall Insulation works by adding an insulating layer of material into the cavity of the wall. This is done by drilling tiny holes into the wall (about 2cm) and then filling the cavity with an insulating material such as pouring foam or polystyrene bead. When the insulation has been filled to the desired capacity, the installer will the seal the small holes with filler or cement.
However, whilst it is fairly quick and easy to install, you will have to recruit a professional installer to do this for you as the process requires specialist equipment.
External Wall Insulation
Properties that were built before the 1930s will have ‘solid brick’ walls, which means there is no gap into which cavity wall insulation can be added.
In these instances, property owners can look to improve the thermal performance of their building though the installation of External Wall Insulation (EWI). As the name suggests, External Wall Insulation is a material that is added to the outside of the property. This usually consists of an insulating layer such as mineral wool or polystyrene, plus a weatherproof outer layer to protect the building fabric and the insulation material from the elements. This outer layer can be made to match the existing aesthetic of the property or chosen from a variety of styles and finishes.
Good quality External Wall Insulation should be breathable, eliminating any risk of mould and damp, and will also improve the resilience of the property to wind and rain.
Internal wall insulation
One drawback of Internal Wall Insulation is that it is highly disruptive. The contents of the room will need to be removed, so it is usually advised to consider installing this type of insulation when you are already undergoing a renovation or decoration project in your home. You will also need to completely redecorate and you will lose floor space within the room
The other major risky thing about IWI is ‘interstitial condensation’. (EWI avoids this as it seals the outside walls and reduces thermal bridging where junctions, corners meet).
To combat this there should be a gap between the outer solid wall and the inner insulated stud wall. The insulation should be on the cold side and a vapour permeable membrane on the warm side of this insulation to enhance breathability and reduce interstitial condensation.