If your home was built before 1920, it probably has solid walls with no gap between. This means that the cavity cannot be filled with insulation, and your house will lose a lot more heat than modern homes. Even if your house was built later than 1920, it may have a reduced cavity or solid walls, so you may need to consider how to best insulate it. There are two options for insulating solid walls; fitting insulation to the outside of the walls, or fitting it inside. There are advantages and disadvantages to both systems.
External Wall Insulation is the most common form of Wall Insulation in older houses where solid walls are prevalent.
What is External Wall Insulation?
External Wall Insulation, or EWI, is the application of insulating boards onto the external walls of the house. The house is then finished with high quality render. We offer a number of options to make your home look really unique – from your choice of colour, to brick-effect, pebble-dash, and other speciality finishes.
How Is External Wall Insulation Installed?
Firstly, if the property has existing render, a render test must be carried out to see if it is strong enough to hold the insulation. If not, all the existing render will need to be removed before attaching the insulation to the brickwork. If the render test shows that the existing render is firmly held in place, the render can be smoothed. This will then be ready for the External Wall Insulation to be applied directly on to it.
Removing pipework from the outside of the building is another important step before installing any External Wall Insulation. These will be reinstalled at the end of the process (and may be extended in some instances). This is one of the main reasons that the insulating process is expensive and time-consuming.
Why Choose External Wall Insulation?
The benefits of External Wall Insulation include;
– Solving problems with your existing render
– Improving the look of your home
– Increasing the value of your home
– Virtually eliminating condensation
– Removes the chilly damp atmosphere
– Low maintenance, not no maintenance
– Giving total weather protection
– No disruption inside your home
– No reduction in internal floor area
What problems are there with External Wall Insulation?
– External insulation can be more expensive than internal insulation, but not always
– It can be difficult to get planning permission in a Conservation Area
– Brick houses will need a simulated brick facing if rendering is not appropriate
– It needs a specialist to design the system and install it properly
– It must be correctly fixed so that it does not bridge the Damp Proof Course or crack
– Rising damp must be rectified before fixing the insulation so that damp is not trapped inside
Is all External Wall Insulation the same?
There are a wide variety of external wall insulation materials and fixing systems available. Each type has different properties, so a good installer will help you decide which is most appropriate for your home.
The key factors you need to take into account for each type of insulation are:
– Fire rating
– Thermal performance (how well it insulates relative to its thickness)
– Biodegradability and environmental impact
– Moisture resistance
– The breathability or vapour permeability (particularly for solid walls)
Using insulation with a high degree of vapour permeability ensures your house can breathe, reducing condensation and preventing mould from forming.
Some of the most commonly used insulation materials are:
Expanded Polystyrene Boards
While these are suitable for insulating floors, they do not insulate as effectively as other materials when used for external wall insulation, so a greater thickness is required to insulate an external wall. This type of insulation material can give off toxic gases in the event of a fire, so particular care must be taken to ensure it is sealed in correctly, which is difficult around door and window frames.
Phenolic Foam Boards
Phenolic foam boards offer better insulation than expanded polystyrene, so a thinner layer of insulation can be used to offer the same amount of insulation which is particularly important when retro-fitting homes.
This material is rather like the fibreglass roll in your loft, but compressed into hard workable pads or panels. Mineral wool has a similar thermal rating to polystyrene but has much better fire proofing qualities.
Polyisocyanurate, also referred to as PIR, polyiso, or ISO, is a thermo set plastic typically produced as a foam and used as rigid thermal insulation. It has a high thermal efficiency, so the panels are relatively thin.
Fixing External Wall Insulation
On level walls, the boards can be fixed using plastic plugs and anchor bolts. On walls which are not even and level, a bonding adhesion coat is used to level the boards. Once the bonding has been left to set for 24 hours, plugs and pins are used to further secure the boards.
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