Is planning permission required for external wall insulation?

Since external wall insulation involves only adding an extra layer to the building's walls and enlarging their depth slightly (by 2-3 in), it does not fall into the category of an extension to the building. Nonetheless, the job often requires some modifications to the external appearance of the building and, therefore, under L1B of the Building Regulations, a Building Notice is necessary. Normally, you would need to present the Council's Building Control with a Building Notice and they would send their Inspector to you to liaise with the installer and sign off an Approval Certificate once the job has been finished.

Please note that there are some exceptions here.

If your property borders with a public pathway or pavement, increasing the depth of your house might be regarded as taking over public space, in which case you will need to obtain planning permission.

Other instances when you require Planning Permission include:

  • Listed Buildings
  • Buildings in an Area of Outstanding Beauty
  • Buildings in a Conservation Area

Having experience in working closely with Building Inspectors, we will be more than happy to act as a liaison between you and them and answer any queries they might have. Moreover, if requested, we can submit the sketches and specifications of products to the Planning Department.

Is thermal cladding cost effective? Would it bring any savings to my budget in the long run?

As home owners we all use various methods of heating, which brings about different results, not necessarily leaving us satisfied. According to the Energy Saving Trust, a standard 3-bed semi-detached house with correctly fitted external insulation cladding would cut down its energy costs by £400. It is also worth noting that a system that complies with the Building Regulations will consequently produce cost savings on external wall insulation, which in turn, will give you a 40% reduction in heating costs.

Please note that if you want to benefit fully from wall insulation, you need to make sure that all the doors and windows in your house are draught proofed and other areas that might be a possible route for the heat to escape, like lofts and roofs, need to be properly insulated.

Another thing to consider if you take heating costs, is that it is dependent on oil and gas prices on the market that tend to increase with time and, therefore, add significantly to our bills.

Why is it necessary to have a Building Regulations Approval?

The Building Regulations Part L1B 2010 state that it is not allowed to exchange or add another layer to any solid wall of your house (except if it is paint) unless you fit insulation. The main purpose of it is energy-saving and cutting the heating costs. This procedure refers to both internal wall makeovers as well as an outside wall rendering (e.g. replacing or applying plaster, cladding or render). Please note that this is relevant to such work performed on at least 50% of the surface of a wall (not to be confused with the 50% of the whole building).

What are the benefits of a solid wall insulation system on external walls?

Undoubtedly, a solid wall insulation system on external walls is the most efficient way of insulating a wall. Also, its thermal performance seems much higher when compared with cavity wall insulation. Solid walls let through up to twice as much heat as cavity walls so insulating them could cut your heating costs down considerably.

The heat loss is generally reflected as a U-Value measure and in case of external solid wall insulation it would normally bring about a 75% minimum decrease in heat loss through the walls depending on thickness and type of insulation materials.

Walls can be insulated internally or externally. When fitting wall insulation from the inside (i.e. dry lining a wall), you will remove the insulating effect of 9 inches from a solid wall behind the internal insulation. However, in case of insulating a solid wall on the outside, the thermal mass of 9 inches of brick will serve as additional insulation, which makes this method 25% more efficient than internal insulation. More importantly, it will also reduce carbon dioxide emissions and, consequently, energy bills.

Other advantages of external wall insulation worth noting are the following facts:

  • It improves weather proofing and sound resistance.
  • It fills the cracks and gaps in the brickwork, which will reduce draughts.
  • It increases the life of your walls by protecting the brickwork.
  • It reduces condensation on internal walls and can help prevent damp, which in turn has health benefits.


All this makes external wall insulation the best and cost-effective solution and, therefore, an investment well worth committing to. Please feel free to contact us for a free survey and no obligation quotes.

Are there any government grants for external wall insulation ?

As per government's Greener Homes Report there are currently no government grants available for external wall insulation and there are no prospects for them in the foreseeable future.

The good news is however that the government would only charge 5% in VAT for fitting external wall insulation, which would amount to a 15% 'funding' through lower taxation. Moreover, there is another governmental incentive in this area – the new property valuation models. The Royal Institute of Chartered Surveyors has been advised by the government to grant a higher value to properties that have implemented energy saving systems, such as external wall insulation. The estimated consequence of this would be a premium of 5-6%, which means that an average property worth £160,000 will gain between £8,000 and 10,000 in its value on the house market.

There is also the Government's proposal of an innovative financing mechanism - the Green Deal plan - launched in early 2012. Under the Green Deal, bill payers will be able to get energy efficiency improvements to their homes, community spaces or businesses at no upfront costs. Instead, businesses will provide the capital, getting their money back via the energy bill. At the heart of the offer is a simple rule: estimated savings on bills will always equal or exceed the cost of the work.

It is a popular misconception / It is wrongly believed that there is no financial incentive for home-owners in this plan (unlike in the 'Feed-in' scheme for solar panels) whereas in fact these energy efficiency measures will invariably lead to lower bills, plus your house will be warmer and carbon emissions lower.

How long will it take to recover the cost of having external wall insulation fitted?

To answer this question you need to take into account the exact earnings on the capital that you have invested to get the insulation installed. To calculate the actual cost, you need to work out the marginal cost, i.e. the variance in the cost of fitting a render only system and its insulated equivalent.

It is estimated that the marginal cost of installing the latter will pay back within 3 to 5 years. According to the Energy Saving Trust, a semi-detached house with three bedrooms with the area of 75m2 of walls will bring annual savings of £350. Therefore, if you add another £15 per metre, the total cost of insulation (i.e. £1125) will be recovered within 3-4 years.

Naturally, the payback period is dependent on various factors (e.g. increase in heating prices, heating patterns) and it will be different for every household. Nevertheless, there is one major advantage of having your house insulated – the property will definitely gain in value on the market as a result of implementing the new property valuation model by RICS.

What does the U value stand for ?

The U value is a measurement of heat transmission through a material or assembly of materials. U-Value is expressed in units of W/m2 and relates to the amount of heat lost in watts (W) per square metre of material. The U value of a material is a gauge on how quickly heat passes through the material and, consequently, how much carbon dioxide is leaking through the walls. Generally, the lower the U value, the greater the resistance to heat and therefore the better insulating value. For example, a new well insulated house will have a U value of approximately 0.25 W/m2 whereas its solid wall equivalent without insulation will be shockingly around 2.05 to 2.10 W/m2. This gives you an insight into how important it is nowadays to make sure your house has a low U value if you want to keep your heating bills down.
Under the Building Regulations the walls below 0.7 W/m2 in U value require fitting insulation while adding or replacing a layer to a wall on the outside. The actual target is 0.3 W/m2 in U value but a higher number might be acceptable if this condition cannot be met due the specific character of the building. A standard installation would amount to 0.35 W/m2 in U value, which denotes a significant 80% upgrade in thermal efficiency of the wall.


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