6.5. Timber joists ceilings and separating / compartment floors Timber joist. Key facts. Sector Guide

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1 Timber joist Ceilings to timber joist floors are an established form of ceiling construction, which is widely used in both new housing and refurbishment. Separating / compartment floors are often specified as fire and sound resisting floors in residential units such as flats and apartments to meet the requirements of national Building Regulations. The ceilings comprise one or two layers of Gyproc plasterboard screw-fixed or nailed to traditional timber joist supports. Isover glass mineral wool insulation can be included in the floor cavity to improve acoustic performance. Timber joist ceiling linings are quick and easy to install, and provide a lining which can be jointed to give a seamless finish ready for direct decoration or a traditional gypsum plaster finish. Key facts Traditional and established method Versatile Use of Gyproc Drywall Timber Screws minimises fixing defects Gypframe RB Resilient Bar to provide enhanced acoustic performance and eliminate nail-popping Can achieve high performance levels Quick and easy to install Gyproc plasterboard - direct fix with Gyproc Drywall Timber Screw Gypframe RB Resilient Bar - indirect fix Sector Guide Offices Commercial Retail Sport & Leisure Education Healthcare Industrial Auditoria Custodial Entertainment Residential - Housing Residential - Apartments Residential - High Rise 06

2 T F E enquiries@gyproc.ie COMPONENTS Gyproc board products Gyproc WallBoard, Thickness Width Gyproc FireLine Thickness Width Gyproc SoundBloc Thickness Width Gyproc Plank Thickness Width Gyproc x s Thickness Width.5, 5mm 900, 00mm.5, 5mm 00mm.5, 5mm 00mm 9mm 600mm 9.5,.5mm 600mm Fixing and finishing products Gyproc Drywall Timber Screws or Glasroc FireCase Screws For a positive direct fix of boards to timber joists. Gyproc Drywall Screws For fixing ceiling lining boards to Gypframe SureFix Bars or Resilient Bars. Gyproc Sealant Sealing air paths for optimum sound insulation. Gyproc jointing materials For seamless jointing. Gyproc Skimcoat, Gyproc Carlite Finish or Gyproc Board Finish To provide a plaster skim finish. Glasroc F MultiBoard Thickness Width 6, 0,.5mm 00mm Isover Acoustic Roll For enhanced acoustic performance. Glasroc F FireCase Thickness Width 5mm 00mm Isover Modular Roll For providing acoustic / thermal insulation. Moisture resistant boards are specifed in intermittent wet use areas e.g. shower areas, bathrooms and kitchens. Also available in DUPLEX grades where vapour control is required. pour check is required. Gypframe metal products Isover Sound Deadening Floor Slab Stone mineral wool For providing enhanced fire performance in some applications. Gypframe RB Resilient Bar Prime dimension 6mm Health and Safety Safety Data Sheets for all Gypsum Industries products are available to download from our website: or via the Technical Sales Department. 07

3 INSTALLATION Direct fix plasterboard ceiling Boards are fixed to ceilings, prior to lining walls and partitions, with the long edges at right angles to the joists. Cut-ends are located over a joist or timber nogging support. Timber noggings (where required) are fitted between joists at room perimeters to support board edges. Noggings may also be required to support board edges in the field of the boards. Boards are preferably fixed to timber supports using Gyproc Drywall Timber Screws, to minimise fixing defects. Direct fix plasterboard ceiling Boards are fixed to ceilings, prior to lining walls and partitions, with the long edges at right angles to the joists. Cut-ends are located over a joist or timber nogging support. Timber noggings (where required) are fitted between joists at room perimeters to support board edges. Noggings may also be required to support board edges in the field of the boards. Boards are preferably fixed to timber supports using Gyproc Drywall Timber Screws, to minimise fixing defects. Indirect fix to Gypframe RB Resilient Bars The bars are fixed through the single fixing flange to the underside of timber joists (at 90 to them) using Gyproc Drywall Screws. The first and last rows of Gypframe RB Resilient Bars are located at all wall perimeters. Boards are fixed to the underside of Gypframe Resilient Bars with long board edges at right angles to the bars. When fixing boards, care must be taken to ensure that the plasterboard fixing screws do not make contact with the joists. Indirect fix to Gypframe RB Resilient Bars The bars are fixed through the single fixing flange to the underside of timber joists (at 90 to them) using Gyproc Drywall Screws. The first and last rows of Gypframe RB Resilient Bars are located at all wall perimeters. Boards are fixed to the underside of Gypframe Resilient Bars with long board edges at right angles to the bars. When fixing boards, care must be taken to ensure that the plasterboard fixing screws do not make contact with the joists. For full installation details, refer to the Installation Guide at 08

4 T F E enquiries@gyproc.ie PERFORMANCE Please refer to section 6. Introduction - for general considerations. Table - Dimensions and performance - Gyproc plasterboard linings Timber joists with suitable timber room perimeter noggings. Noggings also required to support board edges, unless otherwise stated. Gypframe RB Resilient Bars at 50mm centres to underside of joists. 00mm Isover Modular Roll in the cavity. Detail Board type Flooring Joist Joist Fire Estimated laboratory Performance board centres width resistance 6 sound insulation substantiation type (min.) 00-50Hz report Airborne Impact mm mm mins R w db L nw db One layer of.5mm Gyproc WallBoard d C000 One layer of.5mm Gyproc WallBoard a (modified) 8 79 C0600 One layer of.5mm Gyproc WallBoard d C0600 One layer of 5mm Gyproc WallBoard c C0609 Two layers of 5mm Gyproc WallBoard d C06006 Inner layer of.5mm Gyproc WallBoard c C06008 and an outer layer of 5mm Gyproc FireLine Two layers of.5mm Gyproc FireLine d C06009 Inner layer of Gyproc Plank and an outer b C06007 layer of.5mm Gyproc WallBoard Inner layer of Gyproc Plank and an outer d C0600 layer of.5mm Gyproc WallBoard Inner layer of Gyproc Plank and an outer d C0600 layer of.5mm Gyproc SoundBloc Two layers of 5mm Gyproc FireLine d C00 The fire resistance and sound insulation performances are for ceilings incorporating tapered edge boards with all joints taped and filled according to Gypsum Industries recommendations. The quoted performances are achieved only if Gypsum Industries components are used throughout, and the Company s fixing recommendations are strictly observed. Any variations in the specification should be checked with Gypsum Industries. Where boards are fixed direct to timber joists, screw-fixing is the preferred alternative to nail-fixing and minimises the risk of fixing defects occuring. Floor types: a Any structurally suitable wood board flooring. b Wood board t & g flooring, not less than 5mm (finished) thickness. c Wood board t & g flooring, not less than 8mm (finished) thickness. d Wood board t & g flooring, not less than mm (finished) thickness. The acoustic ratings quoted above are based on 00mm deep joists and a walking surface of min. 9.6kg/m. 0 : 5 : 5. If the floor type d is used the fire resistance increases to a full 0 minutes. 5 Noggings to support board edges not required. 6 Board joints must be reinforced with Gyproc Paper Joint Tape for the quoted fire resistance periods to be achieved. Please refer to section. for full details. 09

5 Table - Dimensions and performance - non-combustible board linings 5 6 Detail Board type Flooring Joist Joist Insulation Fire Performance board centres width resistance 5 substantiation type (min.) report mm mm mins Timber joists with suitable timber room perimeter noggings. Noggings also required to support board edges, unless stated otherwise. One layer of 6mm MultiBoard b G009 One layer of.5mm MultiBoard a G060 Two layers of 0mm MultiBoard a G060 Two layers of 0mm MultiBoard a mm Isover 60 G060 Modular Roll 80mm x 0mm MultiBoard strips b mm stone mineral 60 G00 (screw-fixed), with one layer of 0mm wool (6kg/m ) Glasroc MultiBoard (screw-fixed) mm x 0mm MultiBoard strips c mm stone mineral 60 G0606 (screw-fixed), with one layer of 0mm wool (kg/m ) MultiBoard (screw-fixed) One layer of 5mm FireCase S b G0605 (screw-fixed) 00mm x 0mm MultiBoard strips d mm stone mineral 60 G0606 (screw-fixed), with one layer of.5mm wool (8kg/m ) MultiBoard (screw-fixed) One layer of.5mm MultiBoard, d G x 0mm MultiBoard strips and an outer layer of.5mm MultiBoard One layer of.5mm MultiBoard, d mm Isover 90 G x 0mm MultiBoard strips and Modular Roll an outer layer of.5mm MultiBoard The fire resistance performances are for imperforate ceilings with all joints taped and filled in accordance with Gypsum Industries recommendations. The quoted performances are achieved only if Gypsum Industries components are used throughout, and the Company s fixing recommendations are strictly observed. Any variations in the specifications should be checked with Gypsum Industries. Where boards are fixed direct to timber joists, screw-fixing is the preferred alternative to nail-fixing and minimising the risks of fixing defects occurring. Floor types: a mm plain edge wood board flooring. b Wood board t & g flooring, not less than 8mm (finished) thickness. c Wood board t & g flooring, not less than 9mm (finished) thickness. d Wood board t & g flooring, not less than 0mm (finished) thickness, or 0mm plain edge boarding with mm hardboard or plywood. Use 58mm FireCase Screws at 50mm centres. 8mm x 8mm timber noggings are also required between joists and at the perimeter to support board edges. Noggings to support board edges not required. 5 Board joints must be reinforced with Gyproc Paper Joint Tape for the quoted fire resistance periods to be achieved. Please refer to section. for full details. 0

6 T F E enquiries@gyproc.ie Table - Dimensions and performance - upgrading existing lath and plaster ceilings Existing lath and plaster ceiling supported by chicken wire securely nailed to the joists, battened with 8mm x 8mm timber (at 600mm centres with noggings or 50mm centres without noggings). Existing ceiling underdrawn with metal lath securely fixed to the joists. Existing lath and plaster ceiling (up to 0mm thick) supported by chicken wire securely nailed to the joists. Existing ceiling removed and metal lath securely fixed to the joists. Detail Board type Flooring Joist Joist Fire Performance board centres width resistance 7 substantiation type (min.) report mm mm mins One layer of.5mm Gyproc WallBoard d C0609 Two layers of.5mm Gyproc FireLine b C060 mm Gyproc Bonding or with mm b C060 Gyproc Skimcoat or Carlite Finish Two layers of 0mm MultiBoard b G mm x 0mm MultiBoard a G0609 with one layer of.5mm MultiBoard 9mm Gyproc Bonding or with mm c C0605 Gyproc Skimcoat or Carlite Finish The fire resistance performances are for imperforate ceilings incorporating boards with all joints taped and filled according to Gypsum Industries recommendations. The quoted performances are achieved only if Gypsum Industries components are used throughout, and the Company s fixing recommendations are strictly observed. Any variations in the specifications should be checked with Gypsum Industries. Where boards are fixed direct to timber joists, screw-fixing is the preferred alternative to nail-fixing and minimises the risk of fixing defects occurring. Where plaster is applied to ribbed metal lath, the plaster thickness is measured from the face of the lath, and the lath should be installed in accordance with the manufacturer s recommendations. With 0 minutes fire resistance construction, the metal lath is independently fixed with wire supports from the joist sides. Floor types: a Wood board t & g flooring, not less than 0mm (finished) thickness, or 0mm plain edge boarding with mm hardboard or plywood. b Wood board t & g flooring, not less than mm (finished) thickness, or 0mm plain edge boarding with mm hardboard or plywood. c Wood board t & g flooring, not less than mm (finished) thickness, or 0mm plain edge boarding with mm hardboard or plywood. d Any structurally suitable wood board flooring. Assumes no contribution from the existing lath and plaster ceiling. 5 Bridging comprises of a layer of.5mm Gyproc MultiBoard resting on 00mm x.5mm Gyproc MultiBoard strips which are screw-fixed to the sides of each joist flush with the bottom edge, strips fixed at 00mm centres, top and bottom. 6 Fix MultiBoard strips at 00mm centres, top and bottom. 7 Board joints must be reinforced with Gyproc Paper Joint Tape for the quoted fire resistance periods to be achieved. Please refer to section. for full details.

7 Table 5 - Dimensions and performance - compartment / separating floors Platform floor. 00mm Isover Modular Roll between the joists. Floor type c Platform floor. CasoLine MF hung underneath timber joists to give a 77mm cavity, with 80mm Isover Modular Roll between the joists. Floor type c 5 GypFloor SILENT with Gyproc Plank on Gypframe SIF Floor Channels. 00mm Isover Modular Roll in the cavity. GypLyner framework to joists. Separating sub-joist floor comprising of a platform floor. 00mm Isover Modular Roll in the cavity. Floor type c GypFloor SILENT with Gyproc Plank on Gypframe SIF Floor Channels. 00mm Isover Modular Roll in the cavity. Gypframe RB Resilient bars at 50mm centres. Detail Board type Flooring Joist Joist Fire Estimated laboratory Performance board centres width resistance 5 sound insulation substantiation type (min.) 00-50Hz report Airborne Impact mm mm mins R w db L nw db One layer of Gyproc Plank with an outer c C0608 layer of.5mm Gyproc SoundBloc Two layers of 5mm Gyproc SoundBloc c C060 Two layers of 5mm Gyproc SoundBloc b C One layer of Gyproc Plank and one layer b C000 of.5mm Gyproc SoundBloc One layer of Gyproc Plank and one layer b C5008 of.5mm Gyproc SoundBloc Two layers of 5mm Gyproc SoundBloc c C06050 Two layers of 5mm Gyproc FireLine b C000 The fire resistance and sound insulation performances are for ceilings incorporating tapered edge boards with all joints taped and filled according to Gypsum Industries recommendations. The quoted performances are achieved only if Gypsum Industries components are used throughout, and the Company s fixing recommendations are strictly observed. Any variations in the specification should be checked with Gypsum Industries. Where boards are fixed direct to timber joists, screw-fixing is the preferred alternative to nail-fixing and minimises the risk of fixing defects occuring. If in doubt as to whether a floor is to be a compartment or separating floor, or both, please refer to the relevant Technical Guidance Document. Floor types: a Any structurally suitable wood board flooring. b Softwood floor boarding, not less than mm (finished) thickness. c Walking surface of 8mm t & g wood board flooring, spot-bonded with Gyproc Sealant at 00mm centres to a substrate of Gyproc Plank laid on 5mm Isover Sound Deadening Floor Slabs (6kg/m ) laid on a minimum of mm wood based sheet sub-deck nailed to the joists. Normal fixing centres for Gypframe MF5 Ceiling sections (50mm) and Gypframe MF7 Primary Support Channels (00mm). 5 Board joints must be reinforced with Gyproc Paper Joint Tape for the quoted fire resistance periods to be achieved. Please refer to section. for full details.

8 T F E enquiries@gyproc.ie Table 6 - Dimensions and performance - upgrading sound insulation of a basic floor Existing basic floor 95mm x 5mm timber joists at 600mm centres with 8mm t&g wood chipboard flooring. CasoLine MF hung underneath the basic floor (ceiling removed) to give a 77mm cavity. 80mm Isover Modular Roll in the cavity. Upgrading CasoLine MF hung from the basic floor using Gypframe Acoustic Hangers to give a 77mm cavity. 80mm Isover Modular Roll in the cavity. Detail Board type Approximate Floor Laboratory sound insulation Performance weight depth 00-50Hz substantiation Airborne Impact report kg/m mm R w db L nw db Existing layer of.5mm Gyproc plasterboard C0608 Two layers of.5mm Gyproc SoundBloc C06007 Two layers of.5mm Gyproc SoundBloc C060 The sound insulation performances are for imperforate ceilings with all joints taped and filled according to Gypsum Industries recommendations. The quoted performances are achieved only if Gypsum Industries components are used throughout, and the Company s fixing recommendations are strictly observed. Any variations in the specifications should be checked with Gypsum Industries. Table 7 - Dimensions and performance ceilings below roof spaces Timber joists or bottom chord of trusses with timber noggings between joists to support board edges and at room perimeter. Insulation laid between joists. CasoLine MF hung from joists. Insulation laid over ceiling grid. Detail Board type Max. joist/ Min. joist / Insulation Fire Performance truss centres truss type resistance 5 substantiation width report mm mm mins One layer of.5mm MultiBoard mm Isover 0 G060 Modular Roll Two layers of.5mm Gyproc WallBoard mm Isover 0 C0609 Modular Roll One layer of.5mm Gyproc FireLine mm Isover 0 C0607 Modular Roll Two layers of.5mm Gyproc WallBoard mm Isover 0 C0605 Modular Roll Two layers of 0mm Gyproc MultiBoard mm Isover 60 G060 Modular Roll Two layers of.5mm Gyproc FireLine mm stone mineral 60 C0608 Wool (kg/m ) Two layers of 5mm Gyproc FireLine mm stone mineral 60 C0605 Wool (5kg/m ) The fire resistance performances are for imperforate ceilings incorporating boards with all joints taped and filled according to British Gypsum s recommendations. The quoted performances are achieved only if Gypsum Industries components are used throughout, and the Company s fixing recommendations are strictly adhered to. Any variations in the specifications should be checked with British Gypsum. Where boards are fixed direct to timber joists, screw-fixing is the preferred alternative to nail-fixing and minimises the risk of fixing defects occuring. For fire-rated ceilings below roof spaces, noggings are required regardless of joist spacings and plasterboard thickness. Nominal 50mm x 5mm timber battens should be fixed to the side of timber supports where the ceiling boards butt in order to maintain an adequate bearing surface. 5 Board joints must be reinforced with Gyproc Paper Joint Tape for the quoted fire resistance periods to be achieved. Please refer to section. for full details.

9 Environmental Gyproc plasterboard ceilings are unsuitable for use in areas subject to continuously damp or humid conditions. Plasterboards are not suitable for use in temperatures above 9ºC but can be subjected to freezing conditions without risk of damage. Fire protection For reaction to fire classifications for Gyproc and Glasroc boards please refer to Section.. Fire resistance The fire resistances given in Tables,,, 5, 6 and 8 are for imperforate ceilings tested to BS 76: Part 8: 97 or BS 76: Part : 987, or BS 76: Part : 987, or assessments based on these tests. Sound insulation The airborne and impact sound ratings given in Tables, 6 and 7 are for imperforate ceilings and have been tested in accordance with BS EN ISO 0-: 995 and BS EN ISO 0-6: 998, and rated in accordance with BS EN ISO 77-: 997 and BS EN ISO 77-: 997. Airtightness is essential for optimum sound insulation. While most junctions will be sealed with standard jointing materials, gaps at the perimeter of the floor and ceiling, and other small airpaths, can be sealed using Gyproc Sealant. The sound insulation data quoted was measured in the absence of flanking transmission. The performance of the floor in practice will generally be governed by flanking transmission. Water vapour control Where there is a requirement for a vapour control layer, DUPLEX grade boards should be specified as the face layer (i.e. the second layer in double layer linings). The application of two coats of Gyproc Drywall Sealer to the face lining will also provide a degree of vapour control. Please refer also to Timber noggings overleaf. Thermal properties Isover insulation is laid between the joists where required to provide the specified standard of thermal insulation. DESIGN Please refer to section 6. Introduction - for general considerations. Planning - key factors To minimise the risk of ceiling finish defects occurring, seasoned timber with a moisture content not exceeding that recommended in BS 568: Part : 00 should be used. The contractor should ensure that timber supports are accurately spaced, aligned, and levelled. Consideration should be given to using Gyproc Drywall Timber Screws as the preferred method of fixing. Cavity barriers Cavity barriers may be required to satisfy the requirements of national Building Regulations. Please refer to section Cavity barriers. Strength and robustness Timber should be aligned and level, and should meet the requirements of BS 568: Part : 00. The dimensions and assembly of timber supports should be sufficient to allow positive fixing of boards without bounce or undue deflection due to nailing, screwing, or other applied force. When the minimum joist width conditions cannot be met, a timber batten should be securely fixed to the side of those timber supports where ceiling boards butt in order to increase the bearing surface. Please refer to Joist width overleaf. Where plasterboards are fixed at maximum centres in adverse conditions the standard of lining can be affected. Adverse conditions can generally be described as conditions where high humidity occurs, principally in the cold, damp, autumn / winter period. They also refer to buildings under construction during this period where both the structure and wet applications such as plastering and screeding are subject to slow drying conditions. Where a polyethylene vapour control layer is included in the ceiling construction in conditions described previously, condensation can form on the polyethylene surface. This can result in plasterboard becoming unduly damp, and affecting the standard of acceptability of the lining and any applied plaster or textured coating.

10 T F E enquiries@gyproc.ie Imposed loads The designer should ensure that the floor construction is suitable to support any imposed loads. Timber noggings Suitable timber noggings, normally 8mm x 8mm, may be required between joists and at the room perimeter to support board edges and board ends. The provision of noggings depends on the thickness of boards used, and the spacing of timber joists (please see Table 8). In addition, the need for noggings is also dependent on any fire resistance requirements, so Tables and 7 must be referred to. Timber noggings should always be provided at the room perimeter except when using 5mm board or 9mm Gyproc Plank in non-fire rated situations. When fixing DUPLEX grade boards providing vapour control noggings are required regardless of joist spacing or board thickness in order to ensure that vapour control integrity is maintained. In multi-layer plasterboard ceilings, the provision of noggings relates to the outer layer board only, unless otherwise stated. Table 8 - Provision of timber noggings* Board Maximum joist centres thickness with noggings without noggings mm mm mm 6 MultiBoard & & *Tables to 7 must also be referred to for fire resistant ceilings. Joist width Where joist width is less than the minimum stated in Tables - 7, the system may not meet its specified performance. Nail popping Loosening of nails in timber can occur through timber shrinkage (please see Fig 7), or as a result of fixing boards to misaligned or twisted framing. To reduce the risks, boards should be fixed tight to framing members. To minimise any risk of fixing defects occurring use Gyproc Drywall Timber Screws. If nails are the preferred fixing method, the risk of subsequent fixing defects can occur. Fixing to super-dried timber and engineered I beams It has been established by test that Gyproc Drywall Timber Screws are the best solution for fixing to standard softwood, super-dried timber (approximately % moisture content). If engineered I joists are to be used, please contact the joist manufacturer for fire resistance and sound insulation claims and for fixing recommendations. Services Electrical and other small service runs can be routed within the floor cavity. Services should be installed in accordance with standards, guidelines and recommendations. Fixtures / fittings Fixtures should be made into joists, or to supplementary timber. Finishing Please refer to section.5 - Finishing Coat Plasters, section. - Jointing, and section.5 - Decorative Effects. Estimating The estimated construction time is 5-0m / hour (single layer ceiling - boarding only) or 8-0m / hour (double layer ceiling - boarding only) ready for finishing. If the minimum fixing tolerances cannot be met, 50mm x 5mm timber battens should be screw-fixed to the side of the joists where ceiling boards abut in order to extend the bearing surface. Fixing to timber frames A technical information sheet is available to download from our website: 5

11 CONSTRUCTION DETAILS Fig - Joists at 50mm centres using.5mm Gyproc WallBoard - board edge noggings not required unless stated in performance tables * 900 mm 800mm 50mm Room perimeter noggings required. * Note: where Duplex grade boards are specified to provide vapour control, noggings are always required regardless of joist spacing and plasterboard thickness. Fig - Joists at 600mm centres using.5mm Gyproc WallBoard - board edge noggings required unless stated in performance tables * 00mm 600mm 00 mm Room perimeter noggings required. * Note: where Duplex grade boards are specified to provide vapour control, noggings are always required regardless of joist spacing and plasterboard thickness. 6

12 T F E enquiries@gyproc.ie Fig - Joists at 600mm centres using 5mm Gyproc WallBoard - board edge noggings not required unless stated in the performance tables. Room perimeter noggings not required in non-fire rated situations *. 00 mm 00mm 600mm * Note: where Duplex grade boards are specified to provide vapour control, noggings are required regardless of joist spacing and plasterboard thickness. Fig - Twisting of standard soft wood timber joist on drying from 0% to 8% moisture content 7

13 Fig 5 - Fixing boards to trussed rafters 5mm 5mm Fig 6 - Fixing tolerances Table 9 - Fixing plasterboard to timber supports Board Gyproc Drywall Timber Gyproc Nails to fix thickness Screws to fix board for plasterboard for direct direct decoration or decoration or plastering plastering mm mm mm over over over over A 6mm minimum Boards should be lightly butted with a maximum separation of mm. Where a cut edge occurs, dimension A is mm minimum,. Where a bound edge occurs, dimension A would be 0mm minimum. 8

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