Improve loft insulation

Priority for Completion: Very High

This recommendation should be included when the building has accessible loft spaces above conditioned areas and there is not evidence of them being insulated to current standards. The exact benefit will depend upon a wide range of factors including the heating system, the cost of the fuel , how much (if any) insulation is already present and the occupancy of the building together with its shape and layout. Typically, a poorly insulated roof can be responsible for up to 25% (a quarter) of heat lost. These works are generally easy to carry out and are low cost. As such we would suggest that this recommendation is of very high priority for completion.

What is loft insulation?

Loft insulation prevents heat loss through the roof. It is available in many forms and can be fitted either at the eves or the rafters (or in some cases both).

Typically most insulation materials fall into four groups:

  • Loose roll - These are the easiest to install and laid across the ceiling at eves level. Readily available from most DIY stores and cheap, these are normally the preferred method. Typically, this insulation should be at least 270mm thick. If your loft just has insulation to the top of the joists, it probably needs topping up with an extra layer.
  • Loose fill - These materials are poured into the space to be insulated. They are useful for filling awkward spaces that would otherwise be difficult to fill. Particular care should be taken when disturbing this form of insulation as older materials may contain asbestos.
  • Solid board - These products come as foam boards, usually with foil coatings. They are easier to fit to the underside of the roof and don't need to be as thick as loose roll insulation since they are better at keeping the heat in as they have higher thermal resistance. However, they can also be a serious hazard in a fire and usually need covering with a protective layer like plasterboard.
  • Spray foams - These products usually require professional installation and can present similar hazards to foam boards. As a result this is generally the least preferred option.


Installing loft insulation

Exact installation methods depend upon the type of insulation being installed. Loose roll insulation is generally the easiest to install and the work can normally be completed by anyone with good mobility.

Loose roll insulation is available in many forms. A lot of modern insulation comes prewrapped to make it easier to lay. It should be fitted evenly between ceiling joists with at least one additional layer running over the first across the joists (i.e. perpendicular to the first). Rolls should be touching and not compressed (the trapped air is what makes the insulation effective). Uneven insulation or gaps between rolls can lead to cold spots resulting in damp and condensation on ceilings below.

Spacers are now readily available if you wish to board your loft for storage to prevent compression of the insulation. To make sure you receive credit for your insulation in your EPC, make sure you keep suitable evidence of the insulation fitted. It is great to keep dated photos showing the insulation and its thickness in your loft. Photograph a ruler next to it to show the thickness. Make sure the photos also show clearly it is your loft so get the context and key features into the shots. Additionally keep receipts and particularly delivery notes showing the address of your property together with any insulation certificates you are given. You cannot have too much evidence!


Other considerations

Make sure you seek advice if you are unsure how to safely install insulation and the PPE you should use. Most DIY stores will be able to give you good advice.

Take care when working in loft spaces to make sure you do not damage the ceilings below. Care must also be taken around pipework and electrical cables. Some light fittings also penetrate ceilings and appropriate fire prevention measures will need to be considered before insulating near them.

Buildings constructed before 2000 may have asbestos containing materials present which should not be disturbed. If you are unsure seek expert advice before beginning any works as even low levels of exposure can be hazardous to you and those around you.

Whilst you are carrying out insulation work in lofts, check that all you pipework is suitably protected and insulated. It is also a good time to check for any corrosion or minor leaks that you may not have noticed before they become more serious problems.

It is often difficult to find suitable measures that can be implemented in historic and listed buildings to improve energy efficiency without damaging the nature or appearance of the building. Fitting suitable loose roll loft insulation is usually both possible and beneficial. Improving the energy efficiency can help to keep the building in use, widely recognised as the best way to protect it for the future. Fitting the insulation shouldn't normally involve any structural damage or alterations. Additionally, choosing the correct insulation material can improve protection in the event of a fire helping to control its spread whilst still allowing the construction materials to breath to prevent rot and decay.