A Buyer’s Guide to Loft Insulation

Loft Insulation

A quarter of heat is lost through the roof in an uninsulated home. With this in mind, choosing the right insulation for a loft, roof or attic is vitally important. When you think of insulation the most common types that spring to mind are likely to be blanket insulation and foam board insulation but there are other types of insulation that are available that you may not have come across. In order to make the right buying decision and ensure the most effective solution for your application, it is important that you are aware of all the options available.

Types of Insulation

Each type of insulation, despite working towards the same goal, does perform slightly differently and each has its own benefits so it is important that you are aware of all available options in order that you can make an informed buying decision.

  • Blanket Insulation

This is perhaps the most common type of insulation and is commonly made from glass wool. Also known as fibreglass, this is made from glass fibres which are bound together to create insulation. The glass fibres create pockets of air which act as barriers to prevent heat loss, because air is a poor conductor of heat. While it usually has excellent environmental properties as the glass is often made from recycled materials, it isn’t always the best choice for insulating the home.

Despite being easy to install and relatively cost effective, the tiny fibres can be harmful if inhaled of if coming into contact with the skin and if laid in the loft it should be covered by boards and not touched to avoid irritation. It also needs at least 270mm of thickness in the average loft to be a suitable R-Value, making it difficult to maintain head height.

  • Mineral Wool Insulation

Mineral wool insulation is made from a mixture of glass or stone which is heated to a high temperature and spun into a light fibre structure. Mineral wool has a slightly higher R-Value (3.0-3.3) compared to that of glass wool (2.2-2.7) making it slightly more effective. Although heavier than glass wool, mineral wool is much easier to cut, move and fit into place.

  • Foam Board Insulation

Foam board insulation is an umbrella category which includes Phenolic Insulation, PIR, XPS and EPS. This is perhaps one of the most common forms of insulation available today. These boards are commonly manufactured using a solid foam core derived from Phenolic, PIR, Extruded Polystyrene (EPS) or Expanded Polystyrene (XPS). All are relatively low weight products that offer excellent impact resistance and high compressive strength however in order to achieve the required u-values this material has to be used in a large thickness. Phenolic is perhaps the thinnest insulation for a given u-value. To put this into perspective, a 40mm thick YBS SuperQuilt Insulation is equivalent to 70mm of PIR in a roof application.

  • Reflective Foil Insulation

Commonly known as multi-foil insulation, reflective foil insulation is perhaps one of the lesser known and understood types of insulation. Our first experience of multi-foil insulation systems may not have been until perhaps the mid 1990s when this started to become utilised for insulating loft conversions. Despite being less commonly known, this type of insulation provides a range of surprising benefits.

Made up of a single or multiple layers, this thin reflective insulation is a lightweight and easily installed means of increasing thermal efficiency and reducing energy bills. It consists of layers of reflective and insulating materials that allow heat to be reflected back into the room. At the same time, it works by reflecting heat back out of the room which works to keep the room comfortable in the summer months. Multi-foil insulation provides a number of benefits when used alongside traditional insulation. Not only does it help to achieve optimum u-values but it is resistant to corrosion and acts as vapour control membrane. There are also reflective foil insulations available with the added benefit of working as a breathable membrane.

Perhaps one of the most useful benefits where loft conversions are concerned is the fact that using a multi-foil insulation reduces the depth of traditional insulation required and therefore minimises spatial requirements for roofs, in turn maximising internal living space.

Loft Conversion Building Regulations

Current building regulations (Approved Document L1B) states:

  • Pitched roof loft conversion target u-value must be 0.18W/m²K or lower,
  • Loft ceiling target u-value must be 0.16W/m²K or lower

This equates to a thick layer of 90mm PIR between and 50mm PIR below rafters (pitched roof) or 270mm glass wool insulation (loft ceiling). By utilising a layer of YBS SuperQuilt insulation, this requirement is significantly reduced. The diagram below shows the thickness of each material required in a pitched roof application in order to maintain a target u-value of 0.18W/m²K.

SuperQuilt Insulation

As you can see, when utilising a layer of YBS SuperQuilt insulation (pitched roof) the thickness of PIR is reduced to only 70mm, thus reducing the roof space required. If you are looking for ways to meet these regulations whilst providing cost savings and additional benefits that multi-foil insulation can bring, our free and easy to use online u-value calculator will provide the most effective solution for your application. 

For more information on the benefits of YBS SuperQuilt Insulation refer to our website product page.