External Wall Insulation: Explained Cost and Advantages and Disadvantages
Solid walls have been an integral part of the UK architectural realm since the late 18th century. But by the end of 1930’s cavity walls took over solid walls because of their nature of build which makes them highly energy efficient. According to a report, about 15 million homes (71%) in Great Britain have undergone cavity wall insulation by the start of 2024, while homes that underwent solid wall insulation was around 10%.
External wall insulation now cannot be termed just a necessity anymore; it’s an upgrade in many forms. Not only does insulating your external walls help in reducing the overall carbon footprint, there are many positive ripple effects to it. External Wall Insulation (EWI) can save you up to 50% on your energy bills and will drastically improve the thermal efficiency/comfort of your home, and can also impact by increasing the lifespan of your building.
What is External Wall Insulation?
External wall insulation is an insulating process done on outer layers of solid walls of a house. The process is characterised by adding an insulating layer, usually expanded polystyrene, cork or mineral wool. These insulating layers will be fixed to the outer layer of the outside walls and are then furnished with a protective coating, a render or cladding. Once the fixing is done, you may witness an increase in thickness of your external walls by up to 100mm.
What Kind of Walls Require External Insulation?
Houses built as solid walls (houses built before 1920s) require external insulation, whereas houses built as cavity walls (houses built after 1930s) most of the time do not require external insulation, barring exceptional cases.
Cavity walls are built in a way that allows seamless filling of insulation whenever required. They have spaces within the walls where insulation can be injected in. Exceptional cases such as with narrow cavity walls, conventional insulation materials will not aid. In such instances, foam type insulations are considered ideal.
Another type of cavity wall insulation is the partial fill which is more prominent in use where wall areas are exposed to severe windy rain. Partial fill cavity insulation acts as the best solution for preventing water penetration into the inner structure of the building, especially when it rains with heavy winds. Partial fills are characterised by a 50mm gap between the outer layer of the wall and the inner layer of the insulation. This allowance prevents moisture from seeping into the inner layer of the wall.
Other than solid walls, traditional homes with stone walls, timber frame walls supported by wooden structures all require external wall insulation.
Before you decide to insulate, you should know that the difference between a solid wall and a cavity wall lies only in its arrangement. Even a stone wall can be arranged as either a solid wall or as a cavity wall. It is therefore crucial to pre-determine the type of walling arrangement of your building. Extension architecture experts will help you with the complete evaluation. Reach out to us for a brief evaluation.
Can Everyone Afford External Wall Insulation?
Undertaking external wall insulation can be a costly affair for any houseowner. After the British Housing Boom in the 1920s, new constructs were built using cavity walls replacing solid walls for obvious reasons. Today, more than 70% of houses across the UK are built as cavity walls which means at least the remaining 30% of them are solid walls.
It may not be surprising to know that out of the 30% solid walled houses, more than 95% of them are not insulated. The single most impeding factor is the cost.
How Much Will You Save with External Wall Insulations?
You will save at least a minimum of £200 per year if you reside in a mid-floor flat/apartment with two bedrooms.
You save up to £280 per year if you reside in a two-bedroom bungalow.
You save up to £250 per year if you are living in a mid-terrace house consisting of three bedrooms.
If you are living in a semi-detached three-bedroom house, external wall insulation will help you save up to £430 per year.
If you live in a four-bedroom detached house, you can save up to £700 per year.
Factors that Affect External Wall Insulation Cost
Before we investigate the cost of external wall insulation, let’s learn about the factors that affect them.
Materials – The type of insulation essentially decides the cost of materials. Wall insulation warrants the use of rigid insulation boards, mesh, fiber glass, wood fiber, foam board, mineral wool etc.
Location – Region where the work needs to be done plays an important role. London and some parts of the southern regions are generally expensive while in other regions costs can vary.
Labour and Other Costs – Labour cost will depend upon the type and size of the building and the overall complexity and time. There are other costs too that add up, as planning permission, type of finish, inspection and any surveys if necessary.
Steph Fanizza, Architectural Design & Team Manager
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External wall insulation is always a win-win for house owners as it comes with some serious advantages.
- Significant reduction in energy bills, as house owners will be able to save a minimum of £200 to a maximum of £700 every year.
- Huge reduction in carbon footprint.
- Exterior wall insulation shields your inner layers from moisture even during heavy, windy rains, so little no dampness.
- A great investment towards upping the value of your house. Many reports suggest that external wall insulation increases the value of the property up by 12%.
- A great noise insulator.
- A uniform and consistent temperature throughout, giving way for a pleasantly habitable space.
Disadvantages are more like challenges and not actually disadvantages when considering external wall insulation.
The foremost challenge is the cost which in fact is quite high. But with many available government schemes and help from voluntary organisations, it may not seem a dauting one.
It might be a prolonged job in some cases which may cause disruption of routine activities inside your house to some extent.
There might be chances that your house may undergo an apparent change and may not look the same as before.
External Wall Insulation Grants
It is now clear that external wall insulation does not sit light in your pocket. They do warrant a good investment, and that is exactly why there are grants offered by the government and some local authorities to make it a bit more affordable for house owners.
ECO Scheme – The Energy Company Obligation (ECO) is one of the notable initiatives from the government which offers external wall insulation at a zero cost or at a cost that may not burden the owner at all. People can qualify for a complete funding, or a can be funded only for a portion of the project for which there is a criterion that includes yearly income, type of the house and any update or current status of their recent insulation work.
The Great British Insulation Scheme – The grant offers extremely low-cost insulation or even free insulation and is applicable depending upon the EPC (Energy Performance Certificate) ratings of homes. To qualify one needs to ensure efficient energy performance of lighting and heating appliances inside their house and those who have fared well are awarded a higher EPC rating and hence the qualification.
Affordable Warmth Scheme – Exclusively designed for people in Northern Ireland. Renters and owners whose annual income is less than £23,000 can apply to avail the benefit of this scheme.
Conclusion:
You are on the right path if you are looking forward to undertaking external wall insulation at your house. They are not only the most effective way to increase thermal efficiency of your house but are also the most organic way to increase the life span of your building.
Executing an external wall insulation can be a complex undertaking. It is always recommended that such intricate jobs warrant hiring professionals who can see through the project from start to finish.
Find the best experts for external wall insulation with Extension Architecture. Our experience spans years and years of practice and execution by understanding pertinent challenges, type of insulation required, the type of house where the project is undertaken etc. Our experts may also suggest if your property would in fact require an insulation or not. This is done by assessing the building walls, the year of build, and other evaluations pertinent to the construction of your building.
