What insulation should I consider when insulating my roof and rafters?


If you have not insulated your roof and rafters, they are costing you a lot of money in the form of energy bills for every minute that you are using the heating system. This is not an ideal situation to prevent heat loss and save money as heat will escape through the roof and rafters. And a considerable temperature difference will be created because it is a known fact that hot air rises, and in an uninsulated roof, all the heat is bound to escape through the roof eventually. The insulation of roof and rafters is not an expensive procedure and neither a difficult one at that. There are several insulation options available to choose from.

Celotex insulation is one of the options available for the insulation of your roof. This is especially needed in the case of pitched roofs where much heat is lost because of the void. This space can be made habitable by insulating along the plane of the roof pitch with Celotex insulation; to create a warm roof structure with Celotex insulation, it can be used over the roof structure to work as insulating sarking. It eradicates the issue of thermal bridges at the rafters whilst the foil facings, used in conjunction with taped joints, provide an effective barrier to moisture vapor and air leakage. The Celotex TB4000 is a multi-purpose insulation board developed to provide simple solutions for overcoming localised thermal bridges. Celotex TB4000 is made by using  rigid polyisocyanurate (PIR) which containsa combination of blowing agents that have zero ozone depletion potential (zero ODP) and minimal global warming potential (GWP). When you choose Celotex TB4000 you are specifically aiming insulation for elimination of thermal bridges; it is available in varying thickness other than the commonly used standard size, is conveniently cut and shaped for fitting purposes, includes low emissivity foil facings giving improved thermal insulation performance within cavity air spaces and the chief advantage of all- it is a method for long-term provision of reliable energy saving for structures.

Another option is the Celotex GA4000 insulation boards which are also the general purpose and also used for roofs. This kind of insulation is also made using rigid polyisocyanurate (PIR) and offers the same set of advantages of use as the Celotex TB4000. The major difference in Celotex GA4000 is that it comes in the size options of 50mm-100mm while the Celotex TB4000 comes in thicknesses ranging from 12-40mm, making it the thinnest PIR insulation available, in a standard board size of 1200mm x 2400mm. In structures requiring yet more thickness, the Celotex XR4000 insulation can be used.
Just a single continuous coating of the rafters using Celotex insulation can thus reduce the risk of condensation and also avoid the requirement for a ventilation system for the rafter space. In the case of the headroom and rafter depth being limited, Celotex Insulation may be fitted between and over the rafters.

Coming to the Rockwool Flexi-slab, it is a multi and dual-purpose thermal as well as acoustic insulation material that has a distinct flexible edge at one of its ends. The flexible edge offered by the Rockwool Flexi-slab allows for a perfect fit that is reliably retained between the product and its supporting framework for convenient installation and optimal effectiveness. The benefits of using Rockwool Flexi-slab are that firstly its design which comprises of the Patented ‘Flexi’ edge offers accurate fit to all widths, thus, can also be used for the rafters of a pitched roof where the fitting is of significant importance. Moving on its use is very much suited especially for roofs since it will not slump even if the studs happen to shrink. It is also appropriate for use with all common typical metal as well as timber frame spacing. Along with having excellent thermal, acoustic, and fire properties, it is a noncombustible material.

Use the Knauf flex-slab as the fast and convenient way to handle and install roof insulation for any kind of roof because it has flexible edges on all four of the slab’s sides, making it much easier for installation. The Knauf flex-slab is made using ECOSE Technology and recycled material. It has also been awarded the A+ generic BRE Green Guide rating.

Ecotherm may also be used for roof and rafters insulation. Ecotherm is rigid insulation boards that will quickly and easily achieve the needed thermal standards in pitched as well as flat roofs. The use of Ecotherm Eco-Versal allows you to insulate the roof space without the need to alter the thickness of the construction or your method; this is because it needs about half the thickness of the conventional insulation materials to give the same level of thermal performance and thus space is considerably maximized. Using Ecotherm Eco-Versal you may create a warm roof at the rafters’ level and no pipe or tank lagging is needed. Insulation may also be done over, below, or in between the rafters.

Kingspan TP10 is a high performing, rigid thermostat and fiber-free insulation option which is faced on both of its surfaces with low emissivity composite foil facing. It is also aimed at the insulation of warm roof spaces in the face of unventilated or ventilated pitched roofs. It is commonly used as rafter level insulation for tiled or slated roof spaces which are also pitched. Kingspan TP10 is readily available in different size options and also manufactured according to the size required. Kingspan TP10 boards may be used for insulation between, over and under rafters, and as pitched roof sarking.

Plasterboard is typically used with insulation along with a layer of insulating foam bound to it’s the rear side. Sometimes insulated plasterboard is also placed in conjunction with a vapour barrier. Plasterboard is generally a good performance material for insulation of roofs since it is fiber free and rigid thermostat insulation. It’s most suitable for the purpose of insulation, to place most of the insulation between the rafters with an extra layer placed under the rafters. Plasterboard is good for this simple insulation solution; it can be found in a vast variety of rigid insulation products bonded to it. Such as Celotex PL4000 or Ecotherm Ecoliner or Kingspan K18 and Kingspan Kooltherm. Other well-known brands such as Gyproc manufacture an insulated plasterboard called the Gyproc Thermal Basic, Gyproc Thermal Plus and also the Gyproc Thermal Super. Each type of board performs differently eg. the Gyproc Thermal Basic board is EPS insulation attached to the back of the Gyproc Plasterboard, the Gyproc Thermal Plus board is XPS insulation attached to the back of the Gyproc Plasterboard and the Gyproc Thermal Superboard is Phenolic insulation attached to the back of the Gyproc Plasterboard.

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