0800 046 7345 [email protected]

The importance of insulation in acheiving a good epc rating

man installing insulation to loft conversion

Insulation plays a significant role in determining a building’s EPC (Energy Performance Certificate) rating.

The higher the insulation level, the lower the heat loss and energy consumption, leading to a better EPC rating and lower energy bills.

Good insulation helps to keep the heat in during winter and out in summer, reducing the need for heating and cooling systems and contributing to a more efficient and eco-friendly building.


What is an EPC rating and why is it important for a building to have a good one.

An EPC rating is an assessment of a building’s energy efficiency. It measures how much energy it consumes. compared to how effectively it is insulated.

The rating also reflects how well the building retains heat, giving an indication of its potential future energy costs.

A good EPC rating is essential for all buildings, as having efficient insulation and low energy consumption can significantly reduce heating bills by helping to keep warm air in and cold air out.

An average UK property is rated at a D60. Good insulation will help to increase this rating.


The parts of the home that can benefit from insulation.

The 3 main areas of the property that can benefit from insulation are

  • The walls
  • The roof
  • The floors

Each have their own method of being insulated which we’re going to look at.

How To Insulate The Walls Of A Home

There are 2 main types of wall construction in the UK, they are cavity walls and solid walls.

Cavity wall insulation

Most properties built after 1935 will have cavity walls.

Cavity walls can be identified by looking at the pattern of the bricks. If all the bricks are laid long ways, then you will probably have cavity walls.

If you measured the thickness of the wall at a door or window reveal, the thickness of the wall will be at least 260mm wide.

Cavity walls are constructed with an outer brick or block then a gap and then an inner brick or block.

Cavity walls are insulated by holes drilled between the mortar joints and the insulation blown in between the mortar joints.

Cavity wall insulation has to be installed by a specialist approved contractor.

Cavity wall insulation creates minimum disturbance to the householder as all the work is carried out outside and takes around half a day to do.


Solid wall insulation

Most properties built before 1930 will have solid walls. Solid walls are constructed with 2 layers of brick with no gap.

Solid walls can be identified by the pattern of the bricks. When looking at the brick pattern you will see some long bricks and some short bricks. The short brick is actually the same length brick but laid sideways.

If you measured the thickness of the wall at a door or window reveal, the thickness of a solid wall will be less than 250mm wide.

How are solid wall insulated?
Solid walls can be insulated either internally or externally with either a foam PIR board or with mineral wool.

When insulated externally the product is finished off with a silicon render forming a waterproof barrier.

When insulate internally, the wall are finished off with plasterboard which is then plastered over.

Whether the walls are insulated internally or externally is determined by which is the best method for the house. For example, a sandstone house in a conservation area wouldn’t be allowed to have external insulation, but internal wall insulation would be more appropriate.

If walls are insulated internally, then things like skirting boards, electrical sockets, radiators will need to be taken off, then repositioned.

Both internal and external wall insulation take a few days to complete. 

How To Insulate The Roof Of A Home

There are 3 types of roofs that could benefit from improved insulation.

    • Pitched lofts
    • Flat roofs
    • Sloping ceilings

East require a different method to insulate.


Loft Insulation

Loft insulation is one of the most cost effective improvements that can have a big impact in improving the EPC rating. It is the easiest type of roof to upgrade.

Upgrading the loft insulation can be carried out by a competant DIYer, however it’s still likely to be done quicker and better by a professional installation company.

How should the loft insulated

To get the maximum benefit from loft insulation, the insulation should be made up of 2 layers.

The first layer of 100mm should be laid between the joists if not already present, and the 2nd layer should be cross laid across the joists with an additional 170mm.

Care should be taken to take the insulation as far along to the eaves as possible without blocking the natural ventilation from the eaves. This will avoid having a cold spot at the junction of the wall and the ceiling which can lead to black mould problems.


Stop guessing EPC rating


Submit a Comment

Your email address will not be published. Required fields are marked *