Loft insulation materials

There's a range of materials you can use to insulate your loft, attic or roof space.

Types of insulation

Brands to look for

How much insulation do you need?


  Types of insulation

There are four basic types of insulation:

Matting - sometimes called blanket or quilt insulation - is sold as flexible rolls of different thicknesses. The most common type is mineral wool, made from glass or rock fibre. This is the standard material for insulating an empty loft, and is also commonly used in insulating stud walls and under suspended timber floors.  Other materials such as sheep's wool are also available. You should wear a protective mask and gloves when working with mineral wool.

Loose-fill material, made of cork granules, vermiculite, mineral wool or cellulose fibre, is sold in bags. It is usually poured between the joists to insulate lofts. As it is so flexible, it is ideal for loft spaces with awkward corners or obstructions, or if the joist spacings are irregular or not the same size as the matting available. 

Blown insulation is made of fire-resistant cellulose fibre, made from recycled newspapers, or mineral wool. It should only be installed by professionals, who will use specialist equipment to blow the loose material into a specific, sectioned-off area to the required depth.The material may remain loose if used for loft insulation, but can also bond to a surface (and itself) for insulating stud walls etc.

Rigid insulation boards can be used to insulate walls, floors and ceilings. They are mostly made from foamed plastic such as polystyrene, polyurethane (PUR) or polyisocyanurate (PIR).  PUR and PIR board are amongst the best insulation materials commonly used, and so are useful where space is limited.  Rigid board has to be cut to size, so fitting is often a skilled job.


  Brands to look for

Professional installers will supply their own materials, but if you're doing it yourself you'll need to choose the best product for your purpose.  Once you have decided the general type of insulation you need, you will then want to find the right product.  


  How much insulation to use

The thicker the insulation is the less heat you will lose and the more money you will save. But some insulation performs better than others, meaning you can use a thinner layer and still get the performance you want.

All manufacturers of insulation materials will quote the thermal properties of their products. Usually they will quote the thermal conductivity, known as the K-value or lambda.  A low value means the material conducts less heat, and so is a better insulator, so you can use a thinner layer.

Actually calculating the thickness required to achieve a satisfactory performance can be complicated. We have published a guide to insulation materials which is primarily intended for professionals but could help the keen DIYer. If you are not happy working these things out yourself, then we would recommend that you get a professional to help you or to carry out the work for you.


Help for landlords

Until April 2015, the Landlord’s Energy Saving Allowance lets you claim up to £1,500 against tax for energy-saving improvements you have made to each house or flat you rent out. Find out more at the Directgov website.


Save money!

You’ll be charged a lower rate of VAT when you have energy-saving work done to your house, both for the materials and equipment, and for the labour. If the house is new, you pay no VAT at all. Find out more at the HMRC website.


Planning a home improvement project?