How to... insulate your loft

If your loft is home only to cardboard boxes and spiders, you could be wasting a huge amount of energy keeping it warm. Laying proper insulation can slash your carbon footprint and your heating bills – and you don’t have to be a DIY guru to do it.

What are the benefits?

Without loft insulation, you could be losing up to 20 per cent of your heating costs through your roof. It is a simple and effective way to reduce your heating bills, acting as a blanket by trapping heat rising from the house below.

Not only that, it will keep your house cooler in the summer by blocking heat from the sun on your roof. For optimum efficiency you should also consider lagging your pipes and fitting an 80mm hot water cylinder jacket at the same time.

How much will it cost?

Nothing in the long term. Expect to spend around £250 if you do it yourself – it'll cost you twice that if you get the work done a by professional fitter. Check the Energy Saving Trust’s table below to find out how quickly you will make your money back.

It’s also worth finding out if you're eligible for a grant to pay towards the cost of loft insulation.

Payback time

What equipment do I need?

Protective clothing, gloves and masks are essential items, especially if you are fitting mineral wool insulation.
A knife to cut the material to the right size.
Insulation material – this depends on the insulation you have already. If you have none then you’ll need 270mm thick roll-out material. You can choose from mainstream insulation, such as mineral wool, or more eco-friendly types, such as sheep’s wool or loose-fill recycled newspaper. If you already have some form of loft insulation, top it up with rolled or loose-fill material.
Chipboard (optional) – you can add chipboard above your insulation for added protection and to allow you to walk on top.

Step-by-step guide

Mind that dodgy loft ladder!
Clean and dust the gaps between joists.
Start at the eaves and unroll the insulation material between the joists, towards the centre of the loft.
Tuck the end of the roll into the eaves but don’t block them completely.
Mind you don’t insulate below the cold water tank or cover any electric wiring.
At the centre of the loft cut the roll, then go to the other end of the loft and start again. Cut and butt the ends closely together where the lengths meet in the middle.
Repeat along the remaining joist spaces.
Cross-lay a second layer at right angles to the first, this time above the joists.
You won’t be able to see the joists now, so be careful where you step – lay down chipboard to walk on.
To insulate the hatch cut the right sized piece of material, tap nails in each corner and criss-cross string to keep it in place. Watch out this doesn’t catch on the latch.

You're all done – have a nice cup of tea!