Party Wall SolutionsSigma® II Build System offers a zero U-value party wall solution, fully filled with effective edge sealing. This complies with the MIMA (Mineral Insulation Manufacturers Association), Design Guidance Oct 2010, in association with RD Ltd and UKTFA. The system utilises RD Ltd. E-WT-1 and E-WT-2 solutions with fibre batts between the party wall frames and floor zones, fitted as part of the system erection. The sequence of erection allows for one leaf to be installed, with or without sheathing, insulation batts fitted and then the second leaf erected, to complete the process. The use of insulated flexy fire barriers both sides and between the timber frame party wall ends, is sufficient to achieve effective edge sealing. Where required the system provides sheathing for racking strength and secure by design compliance, ideally to one leaf only of the party wall. Where air tightness less than 3 is specified, we recommend the fitting of an air tightness membrane to the face of the studwork, after acoustic insulation is fitted and before plaster boarding is installed. The membrane should be taped to the perimeter wall heads and sealed at laps, ends and junctions, penetrations should be limited, but where required, taped and sealed accordingly. It is recommended where heavily serviced walls occur i.e. kitchens, that an additional service batten and plasterboard layer is fitted to provide a service zone with the party wall intact behind. The fitting of the membrane should be sequenced after the building is weather tight and before first fix, to allow an interim air tightness test to be completed, before services installation. Air tightness membranes are normally supplied and fitted by the contractor. Where air tightness is greater than 3, the first layer of party wall plasterboard can act as the air barrier, with appropriate sealing at edges and joints. Fitting of plasterboard should be similar to the sequence required for the air membrane solution, to allow an interim test to be completed, if desired. Party Wall to External Wall DetailThe build system also offers a range of offsite construction features, including:
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