CEILING INSULATION

Ceiling insulation is known as a 'thermal material' and is the single most important insulation in your home. Without it, your home can't be energy efficient and it's most likely going to be uncomfortable and very expensive either to heat and to cool. Ceiling insulation is measured in terms of R-value. That is resistance to heat. So the higher the number, the better the ceiling insulation is. We all know that heat rises, so when you are heating your home in the winter, the hottest part is actually against the ceiling and that actually maximises the heat escaping through that ceiling. In fact, a standard ceiling without insulation has an r-value of just 0.2. That is not very much at all and so the heat will travel readily through that. In summer time the temperature in your roof space can be as hot as a sauna and that heat will readily push through the ceiling into your home greatly increasing the cost of cooling. So insulating your ceiling properly will make your home more comfortable to live in, much cheaper to operate and it will be good for the environment too. Insulation should be installed in ceilings with unheated spaces, floors above vented crawl spaces, cathedral ceilings and floors over unheated garages or porches.

TYPES OF CEILING INSULATION

Ceiling insulation usually involving the use of :

• Glass or Rock Wool,
• Polyurethane Foam,
• Phenolic Foam.
• Loose-fill materials

GLASS/ROCK WOOL

Glass wool (originally known also as fiberglass) is an insulating material made from fibres of glass arranged using a binder into a texture similar to wool. Glass wool and stone wool are produced from mineral fibres and are therefore often referred to as ‘mineral wools’. Mineral wool is a general name for fiber materials that are formed by spinning or drawing molten minerals. Glass wool is a furnace product of molten glass at a temperature of about 1450 °C from the melted glass, fibres and spun. This process is based on spinning molten glass in high-speed spinning heads somewhat like the process used to produce cotton candy. During the spinning of the glass fibres, a binding agent is injected. Glass wool is then produced in rolls or in slabs, with different thermal and mechanical properties. It may also be produced as a material that can be sprayed or applied in place, on the surface to be insulated. As of 2022, mineral wool rolls are ubiquitous and cheap, meaning a whole ceiling on a standard home could be insulated to the recommended 270mm with a spend of little more than £350.

Products:

Knauf Earthwool Loft Insulation Roll 44 Combi Cut

URSA 10 Diverso Loft Roll

Double Sided Foil RS45 Knauf Fire Insulation Slab

POLYURETHANE FOAM

PIR boards are made by mixing chemicals with a blowing agent. This forms large rigid blocks which are low density, closed cell insulation sheets. The gas which is trapped in the closed cells of the insulation has a very low thermal conductivity. This low thermal conductivity makes the insulation perform better than if it just had air trapped in the cells. They come in different types but the most common type has an aluminium foil backing to each side which makes them easily recognisable. The addition of an aluminium foil facer helps improve the thermal performance. Moreover, they are very nearly as thermally efficient as phenolic boards and cheaper then phenolic boards. PIR boards tend to offer the optimum performance vs price ratio as they’re pretty close to phenolic boards when it comes to r-value and yet they’re cheaper. Although you will need a slightly thicker board to achieve the same r-value.

Products:

Celotex PL4000 PIR Thermal Insulated Plasterboard

Xtratherm Xtroliner XO/STP Soffit Insulation Board

15mm Xtratherm Thin-R PIR Rigid Insulation Board

PHENOLIC FOAM

Phenolic boards are probably the most thermally efficient insulation products used at present. It has a slightly higher r-value and a slightly thinner profile than PIR boards due to the manufacturing process. It offers the thinnest insulation boards for a given specific u-value. As they’re closed cells they shouldn’t absorb moisture or water vapour, unlike open cell products. However, phenolic boards will likely be the most expensive of all the rigid foam insulation options. 

Products:

SR/ST Soffit Insulation Board Xtratherm Safe-R

SR/TB-MF Xtratherm Safe-R Thermal Insulated Plasterboard

Kingspan Kooltherm K118 Insulated Plasterboard

LOOSE FILL INSULATION

Loose-fill insulation consists of small particles of fiber, foam, or other materials. Unlike products such as rolls and slabs, loose fill insulation is blown into the applied area, using a blowing machine. This has a flexible tube to be moved around and pointed at specific areas, to fill them with granulate.

RECOMMENDED CEILING INSULATION THICKNESS

The Building Regulations contain requirements for the renovation or replacement of thermal elements - a thermal element is a ceiling, floor or roof that separates a heated or cooled area from the outside. This could be, for example, ceiling level loft insulation where you provide, replace or increase the thickness of the insulation. These requirements apply where more than 50% of the ceiling area is renovated. Where there is currently no insulation in the roof space, you will need to provide thermal insulation to achieve a U-value of at least 0.16W/m2K. This is typically 250mm of a mineral wool loft insulation roll, for example. Where there is existing insulation achieving a U-value worse than 0.35W/m2K (approximately 125mm of a mineral wool loft roll) you will again need to provide replacement or additional insulation to achieve a U-value of at least 0.16W/m2K. When insulating a ceiling, you'll need to assess several factors before determining the appropriate thickness of the insulation material. When insulating ceilings in warmer climates or when using higher density materials, as little as 8 inches of thickness may suffice. In cooler climates, or in cases where you have sufficient space for more insulation material, you may opt for a thickness between 10 and 12 inches. By insulating your ceiling to a depth of 270mm you can reduce your heating bills by as much as 20%.

Related articles:

How to choose the right Kingspan insulation board for construction?

Cheaper alternative/equivalent to kingspan insulation

Video credit:https://www.youtube.com/watch?v=1oVVgV1gCe8