Celotex GA4000 installation guides for general applications
Pitched roof with Sarking
The void created by a pitched roof can be made habitable by insulating along the plane of the roof pitch with Celotex rigid PIR insulation boards. This creates a warm, potentially habitable roof space in which water pipes and tanks no longer need to be insulated. When used over the roof structure as insulating sarking, Celotex insulation creates a warm roof structure and eliminates thermal bridging at the rafters, whilst the foil facings, used in conjunction with taped joints, provide an effective barrier to moisture vapour and air leakage. The use of a single continuous layer of insulation over the rafters thereby eliminates the risk of condensation and avoids the need for ventilation of the rafter space. Where very low U-values are required Celotex recommends a two-layer system in order to reduce the racking forces on the fasteners required to fix counter- battens to rafters. In this system, the first layer of insulation is applied as a complete layer over the rafters. A second, thinner layer is then fitted over the first layer, between the counter-battens.
Insulation between and over rafters
Where headroom and rafter depth is limited, Celotex insulation may be fitted between and over the rafters. The void created by a pitched roof can be made habitable by insulating along the plane of the roof pitch with Celotex rigid PIR insulation boards. This creates a warm, potentially habitable, roof space in which water pipes and tanks no longer need to be insulated. Where headroom and rafter depth is limited, Celotex insulation may be fitted between and over the rafters. If this two-layer solution is chosen, it is important that the thermal resistance of the inner layer (between the rafters), is less than that of the outer layer (over the rafters). This reduces the risk of interstitial condensation between the insulation layers. The condensation risk also depends upon occupancy and building use. Celotex recommends that a condensation risk analysis is obtained to determine the optimum solution for your project.
Insulation between and under rafters
The void created by a pitched roof can be made habitable by insulating along the plane of the roof pitch with Celotex rigid PIR insulation boards. This creates a warm, potentially habitable roof space in which water pipes and tanks no longer need to be insulated. If sarking felt is being used, a minimum 50 mm ventilated air space must be provided between the felt and the cold side of the insulation in order to minimise the risk of condensation formation. This is known as ventilated construction. With some breathable membranes, the cold side of the insulation may be placed in direct contact with the membrane (check with membrane supplier prior to specification). However, the outer side of the membrane must be adjacent to an air space to allow moisture vapour to escape to the outside of the building, which is known as an unventilated construction.
Insulating interior partition walls and the interiors of external walls
Celotex GA4000 will significantly improve the thermal insulation of new and existing, solid or cavity masonry walls (masonry includes clay and calcium silicate bricks, concrete blocks, natural and reconstituted stone blocks) or timber-frame walls of dwellings and buildings of similar occupancy, type and condition.
The walls of new buildings should be designed and constructed in accordance with the relevant codes of practice, e.g. BS 5628-3.
All walls must be in a good state of repair with no evidence of rain penetration, damp or frost damage. The surfaces of masonry walls should be sound and free from loose material; large projections should be removed and holes filled and levelled. A survey of the wall may be required to establish the extent of any packing that may be required to ensure the support battens provide a uniform plane for the boards to be fixed.
The installation of insulated dry lining systems requires careful detailing around doors and windows to achieve a satisfactory surface for finishing. In addition, every attempt should be made to minimise the risk of cold bridging at reveals and where heavy party walls are attached to the external wall.
In new work the construction must be designed to accommodate the thickness of the dry lining, particularly at reveals, heads, sills and in relation to ceiling height. On existing walls consideration should be given to lining the reveals with a thinner layer of insulation and lining board. Services can be incorporated in the void formed between the insulation and the lining boards, making chasing of the wall unnecessary.
Where the services have a greater depth than the void, the wall should be chased in preference to the insulation. It is recommended that services penetrating the insulation or any vapour check lining board, e.g. light switches, power outlets, be kept to a minimum to limit possible penetration of water vapour. When the system is to be installed in existing buildings it should be realised that a small reduction in room size will occur and that permanent fixtures, e.g. baths, will present difficulties
Steel stud framed wall insulation
Historically, the use of steel framed walls has been found mostly in the construction of commercial buildings. However, the recent growth in Modern Methods of Construction (MMC) has seen an increase in the popularity of lightweight steel framed buildings for both commercial and residential developments. The off-site pre-fabrication of framed panels allows rapid, accurate construction on site.
To minimise building heat losses, rigid thermal insulation is placed on the outside of the frame as a continuous layer to eliminate thermal bridging through the metal studs. This is known as 'warm frame' construction. The very low thermal conductivity of Celotex Tuff-R GA4000 enables high levels of insulation to be achieved with minimal overall thickness.
Beam & block floor insulation
Beam and block floors can be insulated simply by laying Celotex Insulation boards over the floor before applying a screed or board finish. The specification of insulation for ground floors is more complex than that for walls or roofs. This is because the mechanisms for heat flow are affected by the ratio of surface area to perimeter. With a beam and block floor, there is little choice but to install the insulation over the floor before screeding. The ventilated air space beneath any suspended floor can be very cold, so Celotex recommends the application of a continuous vapour - control membrane over the top of the insulation, before screeding, to reduce the risk of condensation forming at the insulation/slab interface. This also prevents screed migration between the board joints, thus avoiding cold bridges.