Twin Skin Metal Cladding

Three grades of URSA HOMETEC ROLL are available;

URSA HOMETEC ROLL 32 - thermal conductivity 0.032 W/mK.

URSA HOMETEC ROLL 35 - thermal conductivity 0.035 W/mK.

URSA HOMETEC ROLL 40 - thermal conductivity 0.040 W/mK.

Design

URSA HOMETEC ROLL is suitable for both walls and roofs using built-up twin skin metal cladding and similar systems.

The bracket and rail system used in twin skin metal cladding introduces a considerable amount of thermal bridging. The brackets should therefore incorporate a thermal break to minimise this effect.

Limiting air infiltration and minimising the risk of interstitial condensation can be achieved by sealing the laps of the inner lining sheet, incorporating a vapour control layer and sealing around gaps and service penetrations in the roof or wall. It should be noted that most metal clad roofs will suffer from intermittent condensation problems on clear, cloudless nights due to clear night sky radiation. If considered harmful a breather membrane should be used over the insulation to drain any condensate away to the gutters.

Metal clad roofs are relatively lightweight so have a poor acoustic performance and will readily transmit sound from external sources and rain or hail falling on the roof. The inclusion of URSA HOMETEC ROLL will improve the acoustic performance considerably increasing the sound reduction from a typical 30dB (uninsulated) to almost 50dB when incorporating 200mm of URSA HOMETEC ROLL. Internally these buildings can suffer from poor acoustic performance due to excessive sound reverberation. A perforated liner tray should be used to allow the sound energy to be dissipated by the mineral wool within the structure.

With increasing levels of insulation it is vitally important avoid thermal bridging; ensure continuity of the insulation around openings and at the junction of elements. Further design guidance on all of the above is contained in the technical design guides available from the Metal Cladding and Roofing Manufacturers Association (MCRMA).

Installation

URSA HOMETEC ROLL is designed to be laid on the inner lining sheet and held in place by the spacer brackets and sheeting rails. The usual procedure for construction is:

1. The structural framing, inner liner sheet, metal spacer brackets (with thermal break) and sheeting rails are installed in accordance with the manufacturer’s instructions.
2. A polythene vapour control layer, if required, is fixed on the liner with all joints lapped and sealed with special care being taken at the junction of elements. Alternatively the laps in the inner liner sheet may all be sealed to create the vapour control layer.
3. The URSA HOMETEC ROLL is laid on the inner liner sheet ensuring there are no gaps in the insulation, around the brackets or around openings and penetrations. The insulation is slid under the sheeting rails where it will be slightly compressed.
4. If required a breather membrane is laid over the insulation prior to installing the external sheeting.
5. The profiled external sheeting should be installed as soon as possible after laying the URSA HOMETEC ROLL to avoid exposure to the weather. Lay only sufficient insulation that can be covered and protected on the same working day, otherwise provide temporary protection. Provide temporary protection during bad weather including rain, wind and snow or freezing conditions.
6. Ensure that any penetrations through the cladding, especially if formed by following trades, are correctly sealed to ensure an air and vapour tight system.

URSA HOMETEC ROLL 40 U-values

For further information and more U-values see our technical brochure in the Documents section. Alternatively please contact URSA Technical Department.

Industry information

Sources of useful additional information