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Insulation for Balconies and Terraces

High performance PIR thermal insulation for use between 19mm plywood sheeting in balcony and terrace applications.

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Providing useable space on a flat roof is an attractive proposition for many building types. For people living in flats and apartments, a balcony is a way of accessing an outside space without being at ground floor level. Terraces, meanwhile, can serve larger dwellings and commercial spaces, providing a hard-landscaped gathering place for a variety of uses.

Where balconies and terraces sit over a habitable space, they form part of the building’s thermal envelope. They must be suitably insulated to meet targets for energy efficiency, while bearing the additional load associated with being used for more than occasional maintenance access.

A warm roof design, with the insulation laid over the structural timbers, remains the preferred option to a cold roof design. A warm roof does not need cross-ventilation, and lends itself to better detailing at junctions with other elements to address linear thermal bridging.

Celotex polyisocyanurate (PIR) foam boards are lightweight, easy to cut and handle, and can be used to insulate areas of flat roof quickly and efficiently. While they already offer a high compressive strength, to resist the dynamic foot traffic load associated with balconies and terraces it is recommended to install the boards with an additional layer of plywood over the top, see the Celotex application datasheet for more information.

The top layer of ply, like the structural timber deck below the insulation, should be a minimum of 18mm thick. The additional layer protects the insulation from the decorative roof finish (such as paving slabs), spreading its weight and the extra foot traffic load more evenly through the insulation layer.


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Celotex products to consider

1200 x 2400mm
0.022 W/mK

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