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Loft insulation FAQS

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How to insulate your loft FAQS

Stuck or need extra help? These are some of the frequently asked questions on Insulation projects.

How much heat escapes through the roof?

On average about 25% of the heat generated by your boiler will escape through the roof of an un-insulated home.

Are there any government schemes that can help me pay for my loft insulation?

There is a scheme called the Green Deal, which allows you to finance the cost of your home insulation improvements and pay it back through the savings you make on your energy bills. To find out more, including how to check if you are eligible, go to

How much Loft Insulation should I use?

To comply with Building Regulations and the current UK government guidelines you need a minimum of 270mm thickness. This should comprise a bottom layer 100mm thick which is placed between the ceiling joists, and a top-up layer above, which should be at least 170mm thick. This should be laid at a 90º angle to the bottom layer to ensure covering of the timber ceiling joists.

If I have existing loft insulation will I need to replace it?

No, your existing insulation will still be effective so you can just lay new insulation on top of it to reach the recommended 270mm thickness.

Do I need to maintain ventilation at the eaves?

Ventilation of the roof space at the eaves must be maintained. Ensure a 25mm air space is maintained between the loft insulation and the roof tile underlay. If you block ventilation to your loft space you may get problems with condensation later.

Should I insulate my water tank and pipework?

Yes; this will prevent them from freezing in the cold months of the year. Do not use loft insulation, there are specific tank and pipe insulation solutions available at Wickes.