Roofgiant Guide to Roof Insulation

According to the Energy Saving Trust, a quarter of heat is lost through the roof in an uninsulated home. At Roofgiant, we stock warm and cold roof options for both flat and pitched roofs, providing you with everything from PIR to foil insulation to rafter roll and many other forms of insulation designed for your loft or attic space. We also supply products from the most trusted brands such as Celotex, Kingspan and SuperFoil.

One of the first things to take into consideration when choosing your insulation is whether you are working with a warm roof space or cold roof space. If you plan on using your loft as a living space (a warm roof space), such as a bedroom or office space, then you will need insulation in the rafters as well as the floor. If you are using your loft as a storage space (a cold roof space), then you do not need to waste money or energy by unnecessarily heating an unused loft space.

All of our roof insulation products have been chosen specifically to make your home as cost-effective and energy-efficient as possible. If you decide to insulate your home then you could be saving on your energy bills, as well as helping to protect the environment. In this guide, we will explain the different types of insulation, their most common application as well as some of their advantages and disadvantages.

Types of Roofing Insulation

Insulation Board

Rigid insulation boards (also known as sheet loft insulation, insulation foam board, loft boards, or rigid foam boards) typically come in sheets and are available in a range of different materials, sizes and thicknesses. They are made by blending a number of materials to form a rigid foam product and are primarily used on the roofs, walls and floors of domestic housing, offices, retail, educational and industrial spaces. Suitable for both flat and pitched roof applications, we stock a range of PIR boards from world-class manufacturers including Kingspan, Celotex and Xtratherm that suit a variety of budget and application requirements.

PIR foam boards are most commonly laminated with aluminium foil facings which provide an additional vapour barrier. PIR insulation boards are also strong and durable, and they achieve U-values with minimum thickness, making it ideal for fast construction schedules and those looking for considerable space savings. Specifically designed to address thermal bridging and reduce localised heat losses, this insulation can be used throughout a building project to help maintain continuity of the insulation envelope.

One disadvantage of this type of insulation is that it can be quite expensive due to its manufacturing process. Rigid foam is also susceptible to sunlight and UV rays potentially damaging it, so it must be stored and installed appropriately. While rigid foam does not require specialised equipment to be installed, you will need to follow strict seam-sealing procedures to ensure it meets building standards.

Insulation Board

Foil Insulation

We stock a few different types of foil insulation including fire-rated, underfloor, multifoil and bubble foil from SuperFOIL. Each of these types of foil insulation offers a 3 in 1 design which incorporates high-performance insulation, a radiant barrier and a vapour control layer. Suitable for all build types, foil insulation is also easy to install with minimal waste and no specialist tools required.

Multifoil insulation is suitable for use anywhere in the home and can be used in conjunction with other insulation products such as mineral wool or foam board. Multifoil is made using advanced modern technology and is certified by BBA and LABC, ensuring that they meet the needs of all new building regulations.

Bubble foil insulation is waterproof and will stop the passage of moisture through your walls, floor or ceiling. Manufactured from corrosion-resistant materials, bubble foil can be used in multiple applications, from walls and floors to garden buildings, garage doors and campervans.

Foil insulation is made from 40% recycled materials and is fully recyclable at the end of its 50+ year lifespan. It is thin, fairly lightweight and much less bulky than other forms of insulation, making it easier to work with. While highly effective in warmer climates, it often needs to be combined with other forms of insulation in colder climates. Foil insulation can also be more expensive due to it being a metal-based product. It may also have the potential to become an electrical hazard should a wiring fault occur and thus must be fitted safely and securely.

Foil Insulation

Mineral Wool Insulation

Mineral wool consists of spun yarn made of melted glass (glass wool) or stone (rock wool). Mineral wool insulation offers excellent thermal and acoustic performance properties and the flexible, robust composition is ideal for warm roofs, loft conversions and cold roofs at joist level. Suitable for conditions and applications where the material may be compressed, mineral wool insulation is usually sold in rolls, and is available in varying thicknesses and widths. The current recommended depth for loft insulation is 270 millimetres for glass wool and 250 millimetres for rock wool.

We stock both glass wool and rock wool from leading manufacturers Knauf and ROCKWOOL. They are very similar insulation materials but there are some key differences. Glass wool has long fibres, high fire resistance, low elasticity and tensile strength and a melting temperature of 1000°C. Rock wool, on the other hand, has short fibres a slightly lower fire resistance, high elasticity and tensile strength and a melting temperature of 700°C.

Knauf Earthwool Loft Rolls are non-combustible, glass mineral wool rolls, that have been manufactured using their revolutionary ECOSE® Technology that contains no added formaldehyde or phenols. It comes in a lightweight quilt for easy installation with thermal conductivity of 0.044 W/mK. Knauf Rafter Insulation Roll is designed for use in warm roofs where pitched roofs are insulated at rafter level and will significantly enhance the acoustic performance of the roof, which is of particular importance in attached and terraced dwellings.

ROCKWOOL Roll is made up of medium density mineral wool insulation. The thermal insulation boasts acoustic properties and is fire resistant, rated A1 Euroclass non-combustible. This insulation solution is suitable for horizontal roof application in all building types or can be used as an acoustic absorber in suspended ceilings. ROCKWOOL HARDROCK Multi-Fix is manufactured from renewable volcanic stone which produces a non-combustible roofing insulation board. The boards are compatible with a range of flat roof systems, including single-ply, EPDM and liquid membranes, bitumen, and green roofs.

While there are many advantages to using mineral wool insulation, the installation process must be carried out by a professional or by someone with the correct protective equipment. This is because inhaled slivers of mineral wool irritate the alveoli and can cause lung disease. Contrary to glass wool, rock wool insulation does not cause that much skin irritation. In terms of environmental friendliness, however, glass wool performs better. Mineral wool insulation may also start to sink, compress and sag as it ages which is why we would recommend laying slightly more than guidelines suggest to allow for settling.

Mineral Wool Insulation

Sheep Wool Insulation

Sheep wool insulation is a great eco-friendly option for homeowners that is fully recyclable and made from sustainable materials. Thermafleece CosyWool is a versatile insulation option that is made in the UK from 75% British sheep's wool and 25% recycled polyester. A great choice for insulating walls and roofs, CosyWool has a convenient compressed form that makes it ideal for quick and easy installation. CosyWool Slabs are flexible but denser than the standard rolls and are designed to provide extra tight friction fit in walls and roofs. They provide excellent thermal and acoustic performance and are highly breathable.

Thermafleece CosyWool flexible slabs are harmless and can be easily installed without gloves or protective clothing, although they do recommend you wear a dust mask in enclosed spaces such as lofts. Thermafleece CosyWool is also not irritating to the skin, eyes or respiratory tract. One of the most obvious drawbacks to sheep’s wool insulation is the cost as it is one of the most expensive forms of insulation. Sheep wool also has to be heavily treated with chemicals during the manufacturing process to ensure it is clean and safe to use, thus it is not completely energy free to produce.