Thermal insulation

Thermal insulation ensures heat generated in your home isn’t lost. Some things you can do yourself to make your home warmer. For others, you’ll need the local authority’s involvement.

This page has information on what you can do yourself, and where you need to get the local authority involved.

More information on energy saving measures in your home is available from

Energy Saving Trust: Energy at home

Things you can do yourself

Loft insulation

Insulating a standard loft can be a fairly simple job if you are confident with DIY, but there are professional companies who will do the work for you. 

The insulation in your loft must meet the minimum energy efficiency values as set out in the building regulations. A second layer of insulation should then be added at right angles to cover the joists, bringing the insulation up to the recommended depth of 270mm. If you have a flat roof, or a room built into your loft, adding more insulation may be a bit more difficult. If you have a standard loft which is difficult to get into or has very limited headroom, then you may need to use a different approach. A specialist company may be able to blow loose insulation material into your loft.

Heating and hot water

You can repair or replace your boiler system without involving the local authority. 

Draught proofing

You can carry out draught proofing, like: 

  • sealing gaps in floorboards and skirting boards
  • insulating a hot water cylinder

Lighting

You can replace your lightbulbs with energy efficient bulbs without involving the local authority.

Underfloor heating

Underfloor heating (UFH) requires much lower temperatures than radiator systems to achieve the same degree of thermal comfort. This means your existing boiler could operate more efficiently, saving money and energy.

Things that involve building regulations

Replacing your boiler and altering electrical systems

These alterations are usually carried out by contractors who can self certify their work. If you use a contractor who is not registered with a self-certification scheme, you will need to submit a building regulations application to the local authority building control team. It will carry out the relevant inspections and issue a completion certificate when work has been satisfactorily completed.

Energy Efficiency Glazing

If you have old or poor quality double glazing, fitting new, high performance windows can cut heat loss through windows by half. Many new windows have an energy label to help you compare their performance. The window’s energy rating will be somewhere between C and A++. Under the building regulations, the lowest rating that an installer is allowed to fit is C. 

To make sure they comply with building regulations, windows are normally fitted by a member of a relevant competent person scheme. 

If you are having your windows replaced as part of a bigger refurbishment, your builder may be able to fit the windows and ask your local authority building control team to approve them. 

Cavity wall insulation

Cavity wall insulation installation is a notifiable building work in the building regulations. However, not every home is suitable. You may not be able to fit standard cavity wall insulation if your house:

  • is particularly exposed to driving rain
  • has cavities that are too narrow, uneven, or blocked with rubble
  • has defective wall ties
  • is prone to flooding

A certified installer will check all of these criteria before deciding whether they can insulate your walls. 

If the installer is registered with the Cavity Insulation Guarantee Agency (CIGA) the installer will in most cases submit the building notice. Building owners should always check that a building notice will be submitted. 

Other insulation options

If your walls are not suitable for cavity insulation, you could consider internal or external wall insulation. This can sometimes be the most appropriate option even if there is a cavity. There are 2 types of solid wall insulation: external and internal. Minimum energy efficiency values for external insulation are set out in the building regulations.

Eco technologies

You may want to add some renewable energy options to supplement traditional energy sources in your extension or conversion. Some of these may involve building regulations and you should check before you begin work, especially if you live in a conservation area or listed building.

Eco technologies can include:

  • solar panels 
  • air and ground source heat pumps or generators
  • wood pellet/biomass boilers
  • log burners
  • wind and water turbines
  • mini domestic combined heat and power generators 
  • mechanical ventilation and heat recovery systems (MVHR)