Office 3
St Paul’s Place, Sheffield
Office Sub-Division Specification
Rev B
October 2017
CONTENTS
1.0 Introduction
2.0 Positioning
3.0 Structural Considerations
4.0 Specification
5.0 Installation
6.0 M&E Services Considerations
7.0 Drawings
1.0 Introduction
This document sets out the works to be undertaken to sub divide the upper office floors of 3 St Paul’s Place into 2 separate tenancies. All works will need to be appropriately designed and installed, to the approval of the developer, including evidence of any testing, commissioning and any other certification, including building control approval.
2.0 Positioning
Partitions must be arranged orthogonally and located to tie in with the façade grid. This will necessitate one of three end conditions; i. meeting a column, ii. meeting a double mullion, iii. meeting a single mullion.
On all floors over 11 metres above external ground level, a minimum of two alternative means of escape must be provided from all separate tenancies for the purposes of fire (unless otherwise justified by a fire engineer).
Floors under this limit can have a single escape if the maximum travel distance from any part of the unit is less than 18 metres provided the maximum occupancy is limited to 60 persons (unless otherwise justified by a fire engineer). Maximum escape distances of 45 metres are permitted if two or more exits are provided.
Where the partitions meet the central core parallel to the existing wall lining they must be finished flush.
3.0 Structural Considerations
3.1 Floor structure construction
The superstructure to the office floors from level 2 upwards consists of steel framed beams with an insitu concrete slabs on composite re-entrant profiled metal decking. The proposed partition system is not to compromise the integrity or performance of the structure.
3.2 Loading
The office floors to the superstructure are designed for a superimposed live load to the general office areas of 3.5kN/m2 plus an allowance of 1.0kN/m2 for partitions. The proposed partition system is not to exceed this 1.0kN/m2 allowance.
3.3 Deflection
Deflection head details to partitions are to be provided to ensure that vertical load from the superstructure is not transferred into the partition system. Superstructure steelwork has been designed for a deflection criteria of span/500 for perimeter beams and span/360 for internal beams. The maximum length of the perimeter beams is approximately 9.0m and the maximum length of internal beams is approximately 15.0m. Reinforced concrete floor slabs on the profiled metal deck floor slabs are designed for a deflection criteria of span/300 between the supporting steel beams. The maximum span of these floor slabs is 3.0m between the centrelines of the steel beams. Refer to section 7.0 for the structural beam layout for clarity on perimeter and internal beams.
3.4 Fixings to top surface of slab
The insitu reinforced concrete slab generally sits on the top flange of the steel frame beams and is 140mm overall thickness with a re-entrant type profile metal deck. The slab thickness over the composite metal deck profiles is approximately 100mm. The bottom track and door framing of the partition system may be drilled, plugged and screwed to the concrete slab using proprietary fixings which must ensure the integrity of the slab along the line of the partition is not compromised. Shot fired type fixings are not permitted.
3.5 Fixings to u/s soffit of slab
Where fixed to the underside of the insitu reinforced concrete slab, the partition systems deflection head must be drilled, plugged and screwed through the profiled metal deck soffit using proprietary fixings into the flat soffit of the deck. Fixings must avoid and maintain minimum edge distances to the re-entrant profiles. Shot fired type fixings are not permitted.
3.6 Fixings to steel beams
Where fixed to the underside, sides or top of steel frame beams the partition systems deflection head must be drilled, plugged and screwed using proprietary fixings. Where present, any fire protection coating or board systems must not be damaged by the partitions or their fixings. Shot fired type fixings are not permitted.
3.7 Fixings to ends of partition at interface with structure or envelope.
At the end of a partition where it interfaces with the shell and core the partition is to be independent of and is not to take lateral stability from the walls, envelope or columns of the building.
4.0 Specification
4.1 Fire
Partitions dividing tenancies do not need to achieve a minimum fire rating, but separation must be provided within the raised access floor and suspended ceiling zones. Partitions to escape corridors must achieve a minimum of 30 minutes fire integrity and insulation unless a suitable automatic fire detection and alarm is installed throughout the storey. The existing automatic fire detection and alarm is an L3 system. This would need to be upgraded to an L2 system as a minimum.
4.2 Acoustics
All sub-division partitions must achieve a site measured performance of minimum 45dB Dw in order to provide the flexibility for meeting rooms to be positioned immediately adjacent to the partitions without the need for any retrofitting. To achieve this rating the partitions must be specified to a laboratory tested rating of 62dB Rw and must be acoustically tested post installation. Evidence of this testing must be provided to the landlord.
This can be achieved by using the specification below:
4.3 Architectural partition specification
K10: 125 METAL STUD PARTITION SYSTEM 90 MINUTE FIRE RATED, 62dBRw PARTITION
· Manufacturer: British Gypsum, or equal and approved.
- Product reference: GypWall Quiet SF.
· Studs:
- Type: GypFrame 70 S 50 'C' studs.
- Centres: 600mm.
· Head condition: Profiled metal deck to soffit of composite concrete slab.
- Deflection allowance: 15 mm, (T.B.C. by Structural Engineer in Movement and Tolerances Report).
· Insulation: Isover APR.
- Recycled content: Not applicable.
- Thickness: 50mm.
· Resilient layer: Gypframe RB1 resilient bar.
· Linings: 2 x 15mm Gyproc SoundBloc to either side.
· Finishing: Skim coat plaster.
- Primer/ Sealer: Not required.
- Accessories: Metal beads/ stops recommended by board manufacturer.
· Other requirements:
- Fire stopping to troughs in metal deck above head channel where partitions form escape corridors and sound stopping in all other locations.
- Fire stopping around services where partitions form escape corridors and sound stopping in all other locations.
- All fixings to Structural Engineer’s guidelines.
- Care must be taken to install resilient bars to manufacturer’s guidelines to avoid creating a direct route for sound through the partitions.
K10: 335 ADDITIONAL SUPPORTS
· Framing: Accurately position and securely fix to give full support to:
- Partition heads running parallel with, but offset from main structural supports.
- Fixtures, fittings and service outlets. Mark framing positions clearly and accurately on linings.
- Board edges and lining perimeters, as recommended by board manufacturer to suit type and performance of lining.
K10: 455 METAL FRAMING FOR PARTITIONS/ WALL LININGS
· Setting out: Accurately aligned and plumb.
- Frame/ Stud positions: Equal centres to suit specified linings, maintaining sequence across openings.
- Additional studs: To support vertical edges of boards.
· Fixing centres at perimeters (maximum): 600 mm.
· Openings: Form accurately.
- Doorsets: Use sleeved or boxed metal studs and/ or suitable timber framing to achieve strength grade requirements for framing assembly and adequately support weight of door.
- Services penetrations: Allow for associated fire/sound stopping.
K10: 505 INSTALLING MINERAL WOOL INSULATION
· Fitting insulation: Closely butted joints and no gaps. Use fasteners to prevent slumping or displacement.
K10: 510 SEALING GAPS AND AIR PATHS
· Location of sealant: To perimeter abutments and around openings.
- Pressurized shafts and ducts: At board-to-board and board-to-metal frame junctions.
· Application: To clean, dry and dust free surfaces as a continuous bead with no gaps.
- Gaps greater than 6 mm between floor and underside of plasterboard: After sealing, fill with jointing compound.
K10: 555 FIRE STOPPING AT PERIMETERS OF DRY LINING SYSTEMS
· Material: Tightly packed mineral wool or intumescent mastic/ sealant.
· Application: To perimeter abutments to provide a complete barrier to smoke and flame.
K10: 560 JOINTS BETWEEN BOARDS
· Tapered edged plasterboards:
- Bound edges: Lightly butted.
- Cut/ unbound edges: 3 mm gap.
· Square edged plasterboards: 3 mm gap.
· Square edged fibre reinforced gypsum boards: 5 mm gap.
K10: 565 VERTICAL JOINTS
· Joints: Centre on studs.
- Partitions: Stagger joints on opposite sides of studs.
- Two layer boarding: Stagger joints between layers.
K10: 570 HORIZONTAL JOINTS
· Surfaces exposed to view: Horizontal joints not permitted. Seek instructions where height of partition/ lining exceeds maximum available length of board.
· Two layer boarding: Stagger joints between layers by at least 600 mm.
· Edges of boards: Support using additional framing.
- Two layer boarding: Support edges of outer layer.
K10: 680 SKIM COAT PLASTER FINISH
· Plaster type: As recommended by board manufacturer.
- Thickness: 2-3 mm.
· Joints: Fill and tape except where coincident with metal beads.
· Finish: Tight, matt, smooth surface with no hollows, abrupt changes of level or trowel marks.
K10: 692 RIGID BEADS/STOPS
· Internal: To BS EN 13658-1.
· External: To BS EN 13658-2.
K10: 695 INSTALLING BEADS/ STOPS
· Cutting: Neatly using mitres at return angles.
· Fixing: Securely using longest possible lengths, plumb, square and true to line and level, ensuring full contact of wings with substrate.
· Finishing: After joint compounds/ plasters have been applied, remove surplus material while still wet from surfaces of beads exposed to view.
4.4 Joinery Specification
Doors to escape corridor to be FD30s fire doors unless a suitable automatic fire detection and alarm system is installed throughout the storey (see 3.1). Their specification (including ironmongery) should match existing timber veneered circulation doors. Refer to architect’s specification as set out in the Outline Specification. The following clear exit widths are required subject to the maximum occupancy of the newly created units:
800mm clear / 60 people850mm clear / 110 people
1050mm clear / 220 people*
*Given potential splits and size of the floor plate it would be unlikely for an occupancy over 110 persons to be required in a single tenancy on a split floor
Skirting to new partitions to match existing mdf skirtings. Refer to architect’s specification as set out in the Outline Specification.
5.0 Installation
Care must be taken when installing the partitions to avoid compromising the fire integrity of the intumescent paint to the steel beams and columns. Where drylining systems cloak intumescent coated steel columns or beams, a recommended minimum gap of 50 times the dry film thickness of the reactive coating should be allowed from the steel surface. Where drylining cannot avoid fixing to steel columns or beams, the drylining board should be used in part or as full encasement to provide fire protection. Refer to the O&M manual for details of the fire protection to steel structure.
Suspended ceiling tiles to be removed along the line of the partition to enable partition to extend up to underside of profiled metal deck/ steel beam where it coincides with a line of structure. Additional grid supports added to either side of the partition location prior to cutting grid. Plasterboard margin to be installed following construction of partition to suit space between face of partition and next full tile.
Raised access floor tiles to be lifted along the line of partition to enable partition to be built from top of structural slab. Tiles to be cut and relayed to suit partition. Pedestals to be repositioned where necessary. Additional pedestals to be provided if necessary to ensure tiles are supported to manufacturer’s guidelines.
The contractor must ensure that they do not cut into fire stops to the external perimeter of the floor slab edge.
6.0 M&E Services Considerations
6.1 Fire
Once the internal partitions have been installed the sprinkler and smoke detector layouts will need to be re-configured to suit. The detection zoning and interface with the alarm will need to be updated.
6.2 Mechanical Services
Each sub-division will need to be assessed individually to review the impact on all installed services. The review will need to encompass all of the following items:
· Location of fan coil units
· Route of air ducts
· Route for exhaust air within the ceiling plenum
· Access to the landlord’s risers for any new services to be installed by the in-coming tenant. Eg. Refrigeration pipework for air conditioning
· Potential requirements to re-position sprinkler heads (as above) so that the spacings/distances to partitions align with the BS recommendations
· Locations of grilles and diffusers associated with the air conditioning system
· Any impact on the energy metering strategy
All proposals must be drawn up for approval of the landlord prior to commencement of works.
Any air ducts which penetrate the partition will require cross talk attenuators to maintain the acoustic protection required between tenancies and fire dampers where the partition forms part of a protected escape route.
Where the partition location divides the tenancy from the pair of exhaust air ducts that extract air from the ceiling zone an opening(s) will need to be provided in the partition above the ceiling to allow exhaust air to travel back from the new unit to the ducts. These openings will need to be equipped with cross talk attenuators (and fire dampers if passing through a fire rated partition).
The BMS software will require modification to suit the sub-division.
6.3 Electrical Services
Each sub-division will need to be assessed individually to review the impact on all installed services. The review will need to encompass all of the following items:
· Luminaire positions
· Whether a new separate metered distribution board is required
· Additional luminaires to suit any new corridor/ lobbies created by the proposed layout
· Exit signage locations
Illumination levels to suit the specifications described in the Outline Specification.
7.0 Drawings
Indicative plan details are included to illustrate the 3 different partition location scenarios: