External Wall Insulation

External Wall Insulation

Insulating your solid walls could cut your heating costs considerably, and make your home more comfortable.

If your home was built before the 1920s, its external walls are probably solid walls rather than cavity walls.

  • Solid wallshave no gap, so they can’t be filled with cavity wall insulation.
  • Cavity wallsare made of two layers with a small gap or ‘cavity’ between them.

Solid walls can be insulated though – either from the inside or the outside. This will cost more than insulating a standard cavity wall, but the savings on your heating bills will be bigger too.

Work out your wall type

If you have solid walls, then they’re almost certainly not insulated – but the first thing you need to find out is what sort of walls you have.

If you can see the brickwork on the outside of the house, look at the pattern of the bricks as this can show how the wall has been built.

  • If your home has solid walls, the bricks will have an alternating pattern, with some bricks laid across the wall so you can see the smaller ends from the outside.
  • If your home has cavity walls, the bricks will usually have an even pattern with all the bricks laid lengthways.

If the brickwork has been covered, you can also tell by measuring the width of the wall. Examine a window or door on one of your external walls.

  • If a brick wall is more than 260mm thick then it is probably a cavity wall.
  • A narrower wall is probably a solid wall. Stone walls may be thicker still but are usually solid.

If you live in a house that has a non-traditional construction such as a concrete, steel or timber-framed building, you will need a specialist installer with experience in insulating your building type to advise you on your options.

Internal vs external insulation

Internal insulation

Internal wall insulation is done by fitting rigid insulation boards to the wall, or by building a stud wall filled in with insulation material such as mineral wool fibre.

  • Generally cheaper to install than external wall insulation.
  • It will slightly reduce the floor area of any rooms in which it is applied (the thickness of the insulation is around 100mm).
  • It can be done room by room.
  • It requires skirting boards, door frames and external fittings to be removed and reattached.
  • It can make it hard to fix heavy items to inside walls – although special fixings are available.
  • You’ll need to fix any problems with penetrating or rising damp beforehand.

External insulation

External wall insulation involves fixing a layer of insulation material to the wall, then covering it with a special type of render (plasterwork) or cladding. The finish can be smooth, textured, painted, tiled, panelled, pebble-dashed, or finished with brick slips.

  • It can be applied without disruption to the household does not reduce the floor area of your home
  • It will renew the appearance of outer walls.
  • It will improve weatherproofing and sound resistance.
  • It fills cracks and gaps in the brickwork, which will reduce draughts.
  • Increases the lifespan of your walls by protecting the brickwork.
  • Reduces condensation on internal walls and can help prevent damp (but will not solve rising or penetration damp).
  • It is best installed at the same time as external refurbishment work to reduce the cost.
  • It requires good access to the outer walls.
  • It is not recommended if the outer walls are structurally unsound and cannot be repaired.

Grants are available under the Government’s Energy Company Obligations (ECO) scheme. There are three types available:

1-Carbon Emissions Reduction Obligation (CERO) Grant

  • Available for every suitable home – no personal qualifications required

2-Home Heating Cost Reduction Obligation (HHCRO) Grant

  • You qualify for this if you are a homeowner or private renting tenant on certain state benefits

3-Flexible Eligibility

  • Social Housing with an Energy Performance Certificate rating of E,F or G can qualify for HHCRO funding under Flexible Eligibility
  • Local authorities that submit a statement of intent can qualify vulnerable residents for HHCRO funding regardless of their benefit eligibility under Flexible Eligibility

If you have cavity walls, in theory EWI could be put on top of it, but this would be unusual.

Cavity walls require cavity wall insulation, which is different from EWI. Cavity walls have built-in spaces within the walls where insulation can be injected into. EWI is installed on properties with solid walls with no cavities.

Cavity wall insulation is generally considered sufficient insulation and you shouldn’t have any need to add a different type of insulation on top. What’s more, funding for EWI will not be distributed if there is any evidence of cavity wall insulation in the walls you plan to externally insulate.

Sometimes – it depends on what opportunities there are in your area. Generally you cannot get EWI installed for free, but there are grants available which you could use to help with the cost. Some local authorities are running schemes that blend EWI grants with other sources of funding and in some circumstances installations are fully funded. However, for the majority of cases, grants for EWI will only support a proportion of the total cost.However the New Green homes Grant starting in September 2020 may cover the full cost

Installers will buy the actual insulation product for you from an EWI manufacture and add this to the cost of the install. Contacting a company like ours means we can help you with grant applications and finance plans as well as the installation. We work with market leading manufacturers, have a network of industry approved EWI installers and funding in place to support the cost of the work.

Sometimes. EWI is considered ‘permitted development’ so typically does not require planning permission.

However, if you live in a listed building or a conservation area then you may need planning permission to get EWI installed. Some local authorities stipulate that planning permission is required if the outside of your house is going to change in colour or texture, which is often the case with EWI.

As a rule, we would recommend you always check with your local planning office before EWI is installed on your home. If a planning application is required, then it is highly unlikely that you will be refused.

You must apply for planning permission if:

  • The thickness of the insulation will mean your house infringes into someone else’s land or a public walkway or road
  • You live in a listed building
  • You live in a conservation area
  • Your local authority has strict rules about the colour and texture of properties in different neighbourhoods
  • Yes, often it does. EWI will improve the visual appearance of your property adding to its resale value.
  • Better insulation will also improve your home’s Energy Performance Certificate (EPC) rating which is an influencing factor when selling a property.
  • According to researched published by the Government in 2013,moving from EPC band G to E or from band D to B can increase the value of your property by approximately £16000 in England.
  • The thickness of the insulation can vary depending on which EWI system you choose. Typically, EWI will add around 100mm to your house.
  • Yes, it certainly helps to prevent damp from occurring.
  • Insulating the outside of your walls helps to raise the temperature of the internal walls, thereby reducing the risk of condensation forming. It also provides a waterproof, protective barrier against penetrating damp.
  • Yes, EWI should come with a guarantee for both the installation and the actual product.
  • All quality installers will offer a guarantee for their labour. The manufacturers of the EWI system should also offer a guarantee. For example, SPSenvirowall currently provide a 12 year guarantee on their domestic systems.
  • If ECO funding is used to support the cost of EWI on a domestic property, a 25-year insurance backed guarantee should also be provided. This guarantee will be issued by your installer, but it will be underwritten by an independent insurer. This means that you are protected if your installer or system manufacturer ceases to trade in the future. The terms of your guarantee will still be met and honoured by the insurer.
  • Considering the impact of cost savings from fuel bills, the value added to your home and the difference it will make to the environment and your carbon footprint, EWI is well worth it. Your house will be more energy efficient, feel warmer and look great!
  • You can expect EWI to last for decades. In the UK, many systems have been installed with a 25 year guarantee, however quality EWI systems are designed to last considerably longer.

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