Types of Loft Insulation

It is estimated that 25% of heat is lost through the roof of an uninsulated home. With the ever-increasing cost of fuel, it makes sense to ensure your loft is as well insulated as possible. Especially as, if installed correctly, the cost of loft insulation will pay for itself many times over by way of energy saved.

When getting a survey carried out on a house, the surveyor will note whether the loft space has insulation and whether it is sufficient or not. Loft insulation information is also provided in a property’s EPC. For any new houses or new loft conversions there are building regulation requirements in relation to levels of insulation that must be adhered to.

There are a variety of loft insulation types and materials to choose from. The most common material used is fibreglass (or glass wool) insulation in blanket or roll form. This loft insulation is good value, performs well and is easy to install as it can be easily rolled out between the joists. If you have fibreglass insulation in your loft, it is worth checking its thickness (aim for 270-300mm) and ensure it hasn’t become squashed down or damp, both of which significantly reduce its thermal performance. It is easy enough to top this type of insulation up or replace it yourself, although protective equipment is advised.

Blown insulation, also known as loose fill insulation, is most often made from paper, fibreglass, cellulose or plant fibre mixed with a mineral fire retardant. It performs well but generally requires specialist equipment to install it correctly as it is made up of small pieces of fibre that cannot be rolled out (hence the name, as it is literally blown into place).

Insulation boards or slabs have the advantage of being easier to secure between roof rafters and behind cupboard doors and hatches, as they are more rigid than the above options. There are a whole range of insulation boards, from PIR to Rockwool, with excellent fire-resistant properties. Insulation boards generally achieve greater thermal efficiency at a lesser thickness than loose fill or fibreglass.

Foil insulation, otherwise known as multifoil or reflective insulation, is useful when insulating between roof rafters as it reflects heat back into the room in the winter, and prevents heat from entering in the summer. It is light weight and doesn’t absorb moisture, however it does need to be dust free to perform well.

There are a few other, lesser used types of loft insulation materials to consider. One is sheep’s wool, which comes in a roll ready to use, similar to glass wool. It has natural insulation properties and is more sustainable than many of the man made alternatives. Another type is made from plastic bottles which are spun into polyester fibres.  It is durable and performs well.

When choosing the type of loft insulation to use, it’s important to consider a range of factors such as insulation value, cost, ease of installation and any specific requirements your home may have. Consulting with a professional loft insulation installer will help ensure that you choose the right type for your home.