Loft Insulation can save energy and money
Have my neighbours done this?
What is it?
Reduces the amount of heat lost through the roof
What will it save me?
Saves up to £200 per year in most homes
How do I get it?
Careful DIY or insulation contractor job
What does it cost?
Contractor cost around £3-500 or DIY £1-200 (2013)
What are the technical details?
The Building Regulations 2010 requires lofts to be insulated to achieve an approved thermal standard and suggests one way to achieve this is to lay mineral or glass fibre insulation over the ceiling to a depth of 270mm.
The most effective way is to lay 100mm between the ceiling joists and a further 170mm over the top of the insulation so that the joists are fully covered.
If you already have some loft insulation, say up to 100-150mm thick, then it's well worth adding another layer to take the total thickness up to about 270mm and is fitted so that the ceiling joists are covered.
Alternative materials can be used such as rigid polyurethane foam or expanded polystyrene boards which have better insulation properties and can therefore be of lesser thickness. This is useful if the roof space is to be boarded for storage. In this case, fit 75mm thick insulation boards between the ceiling joists and 75mm thick boards over the joists.
Other more environmentally friendly materials can also be used such as sheep's wool, cellulose fibre (made from recycled paper) and quilt made from recycled plastic bottles. Loose fill materials should be avoided since they are likely to blow around the roof and fall out every time the loft hatch is opened.
A loft with 100mm of insulation will already be saving 70% of the heat lost through the roof. Increasing the depth of loft insulation from 100mm to 270mm will save another 20%.
Loft insulation is carried out by insulation contractors who ensure it‘s fitted correctly. However, it is a relatively easy DIY job if done with care and wearing the right clothing. It’s important the insulation isn‘t forced into the eaves to ensure that ventilation openings aren’t obscured to avoid condensation issues.