Planning - key factors
The position of services should be pre-determined and their installation planned into the frame erection stage. It is important that all parts of the lining system, including the thermal insulation, should remain independent of the external walling. The lining is erected with the external walling in place and the windows and doors fixed.
Where the wall height exceeds the available length of the ‘I’ stud, sections of stud can be spliced together to the required length using 600mm lengths of the appropriate floor and ceiling channel, fixed with four British Gypsum Wafer Head Drywall Screws in each flange to each side, (see WHITE BOOK Construction details – 2). Where greater heights than listed in Table 1 are required, it may be possible to brace the lining back to the structure. Note that the system is non-loadbearing and should not be used to provide lateral restraint to masonry or other external wall constructions.
GypLyner IWL can be used as an independent lining to improve the sound insulation of new or existing masonry walls. Acoustic testing on a basic masonry wall construction achieving Rw 45 dB sound insulation gave a 14 dB improvement when the wall was lined with GypLyner IWL (single board). A 16 dB improvement was achieved with a double layer lining. Please see WHITE BOOK Table 5. Special detailing is required at junctions with sound insulating partitions in order to maintain acoustic performance, (see WHITE BOOK Construction details – 5).
Cavity barriers should be included where necessary. If both sides of the cavity are formed by non-combustible or Class 0 materials, barriers are necessary only every 20m. The nature of the barrier and its fixing should not detract from the general performance of the wall. Refer to WHITE BOOK section 10 – Cavity fire barriers.
Fixing floor and ceiling channels
Gypframe Floor & Ceiling Channels must be securely fixed with a row of fixings at 600mm maximum centres. For 94mm channels and above, two rows of staggered fixings are required, each row at 600mm centres and each fixing 25mm in from the flange. If the floor is uneven, a 38mm thick timber sole plate equal to the width of the channel should be used.
If the concrete or screeded floor is new, consideration should be given to the installation of a damp-proof membrane between the floor surface and the channel or sole plate.
The system can accommodate deflection at the head with suitable detailing incorporating Gypframe Deep Flange or Extra Deep Flange Floor & Ceiling Channels. Contact the Saint-Gobain Technical Academy for further guidance. Refer to WHITE BOOK section 3.2.2 – Principles of building acoustics.
Damp or rain penetration
In refurbishment projects, where damp or rain penetration may exist, normal corrective measures, such as a new damp course, tanking, or external wall coating, must be taken prior to the installation of the dry internal lining. The cavity between the external wall and the lining system could be drained and ventilated to the outside.
Uncontrolled air movement through the drylining cavity can result in excessive heat loss from the building. This can be reduced in practice if the abutting elements and the background are well fitted, and junctions are sealed.
The designer should also specify a method of restricting air movement around the perimeter of suspended timber floors, such as the provision of a flexible seal between the floor and walls.
Isover Steel Frame Infill Batts are inserted to a friction-fit within the stud cavity. The slabs are self-supporting, receiving internal support from the stud flanges, except where 50mm insulation is fitted into Gypframe 92 I 90 ‘I’ Studs or Gypframe 146 I 80 ‘I’ Studs. In this case, a 150mm x 50mm strip of Isover Steel Frame Infill Batts is inserted to retain the slab.With Gypframe 146 I 80 ‘I’ Stud, two strips of insulation should be inserted to retain the slab.
The stud cut-outs can be used for services provided that the Isover insulation remains in place. The positioning of stud cut-outs is shown in Construction details – 1.
Both horizontal and vertical services can be included behind the lining system, and accessed via a fire-rated Gyproc Profilex Access Panel. Refer to WHITE BOOK section 14 – Products, Access panels.
Surface mounted services should be located against the plasterboard lining, and fixed through the lining to the stud framework. Any interruptions in the lining integrity will downgrade its performance. The installation of electrical services should be carried out in accordance with BS 7671. Refer to WHITE BOOK section 3.5 – Service installations.
Lightweight fixtures can be made directly to the partition linings. Medium weight fixtures can be made to Gypframe 99 FC 50 Fixing Channel. Refer to WHITE BOOK section 3.5.2 – Service penetrations and fixing into drywall systems.
For further details on tiling guidance: Refer to WHITE BOOK section 13 – Finishing systems and decorative effects, Tiling.
Refer to WHITE BOOK section 13 – Finishing systems and decorative effects.
For more information refer to the British Gypsum SITE BOOK.