13.1 General
13.1.1 Scope of Work
Suspended ceilings shall be as specified in Schedule of Finishes..
13.1.2 Relevant standards
Conform to the recommendations of the following British Standards and Codes of practice where applicable:
BS 1191 Specification for Gypsum Building Plasters BS 1230, Part 1 Gypsum Plasterboard
BS 8000, Part 10 Code of Practice for Plastering and Rendering.
BS 8212 Code of Practice for dry lining and partitioning using gypsum plasterboard.
CP 290 Code of Practice for Suspended ceiling and linings of any dry construction using metal fixing systems.
13.1.3 Fire resisting properties
The exposed surfaces of all suspended ceilings are to have “Class O” surface spread of flame all in compliance with the requirements of the local Fire Prevention Officer.
In addition the completed proprietary suspended ceiling assemblies are to provide half an hour fire resistance when tested in compliance with the requirements of the local Fire Prevention Officer.
13.1.4 Literature and samples.
Provide comprehensive technical literature fully explaining the proposed ceiling installations for the approval of the Engineer.
Provide samples of various tile finishes, colours, textures and patterns for selection by the Engineer.
Complete sample trial area, corner 3 x 3m prior to commencement of work.
13.1.5 Shop drawings
Provide shop drawings of the proposed suspended ceiling installation for the approval of the Engineer. Shop drawings shall include the following information:
- Room layouts with reflected ceiling plan showing locations of all ceiling mounted items such as light fixtures, a/c diffusers, smoke detectors, etc.
- Also indicate all other items which are to be located within ceiling space (such as A/C units).
- Method and location of anchorages to structure.
- Location, size and detailing of access panels.
- Location and detailing of movement joints.
13.1.6 Personnel
Installation of all suspended ceilings shall be carried out by suitably experienced tradesmen or in the case of proprietary ceilings a franchised applicator of the ceiling manufacturer all to the approval of the Engineer.
13.2 Materials
13.2.1 Plasterboard
Plasterboard suspended ceilings shall comprise12.5mm thick standard and for bathroom and wet room moisture resistant plasterboard all with tapered edges or similar plasterboard which conforms to BS 1230 to the approval of the Engineer on proprietary galvanised steel or aluminium suspension system..
Where specified for external use plasterboard to be approved exterior quality gypsum ceiling board.
13.2.2 Ceiling Tiles 13.2.2.1 Steel Ceiling Tiles
Metal ceiling tiles; FERRO- Anti Bacterial F90 600 x 600 clip-in system as per manufacturers’ specification.
Colour : To engineer's approval.
Tiles to be machine cut at all extremities.
Tiles to be set-out and co-ordinated with all service location points and lighting layout.
Contractor shall prepare a detailed co-ordinated setting out plan for Engineer’s approval.
13.2.2.2 Perforated Metal Ceilings
Perforated metal ceiling tiles as per manufacturers specification.
Colour : To engineer's approval.
Comprising Q-clip suspension system, perimeter trims, access panels for services. Electrolytically galvanised steel 0.5mm, micro-perforated Rd 1522 to give alpha sound absorbtion of between 0.66 and 125 and 5000 Hz to DIN 52212.
13.2.2.3 Plain Metal Tile Ceiling
Plain polyester powder coated ceiling tiles; 600 x 600; exposed lay-in grid, to approved sample.
13.2.2.4 Mineral fibre ceiling tiles
Mineral fibre tiles as per manufacturers specification. Pattern to be fissured or similar to approved sample.
13.2.3 Stonewool
Stonewool proprietary suspended ceiling on proprietary galvanised steel or aluminium suspension system.
Ceiling tile to be 18mm hygienic as per manufacturer's specification.
Plasterboard-related materials
Plasterboard nails: Galvanised or otherwise zinc coated steel with 2.5mm minimum shank diameter and 7mm minimum head diameter; lengths as BS 8212 clause 6.3.
Jointing accessories As follows:
a) Jointing compounds for bedding and finishing joints to comply with BS 6214.
b) Joint reinforcing tape to comply with BS 6214.
c) External angle : paper tape reinforced on both edges with zinc coated flexible steel strip bonded to the paper.
d) Edge and corner beads : galvanised steel to BS 6452 : Part 1 13.2.4 Access
Unless the ceiling systems is fully accessible, access panels shall be provided and installed to allow access to mechanical, electrical and any other
appurtenance within the ceiling void. Such access panels shall be of proprietary type with hinges as supplied by “Arrow” type CD/PB/SB or CP/PB/SB/F sizes to suit access purpose or equal and approved finished flush with appropriate trim. Fire rating to match remaining ceiling installation.
13.3 Execution
13.3.1 Setting Out
Set out the work with the following objectives:
a) To establish the correct ceiling level.
b) To establish panel centres and joint lines, etc including the layout at obstructions and in irregular areas.
c) To avoid or minimise cutting of ceiling panels.
d) To agree the positions of access panels, luminaires, grilles and other services equipment, fire checks and everything else that affects setting out.
e) To establish the location of all battens and other fixing points.
13.3.2 Installation
Install all ceilings complete and securely fix all components all in accordance with the manufacturer’s written instructions.
Also comply with the following:
a) Erect the suspension system complete with hangers, primary grid and ceiling grid.
b) Provide additional suspension for luminaires, grilles, ducts and other equipment to be supported, including adaptation and span bars, etc where necessary.
c) Adapt the system for obstructions, bulkheads and sloping sections.
d) Fix fire stopping and insulation e) Fix all perimeter supports
f) Fix the ceiling panels and tiles including access panels, luminaires and other equipment including that provided by others.
g) Fix perimeter and other trim
h) Check and adjust as necessary and leave truly level i) Tolerance shall be 3mm in 3m
j) Do not anchor hangers to equipment, pipes, conduits or other appurtenances.
k) Incorporate light fittings, a/c units, heat detectors and any other ceiling-related items in accordance with the approved shop drawings and in compliance with the related manufacturer’s instructions.
l) Carefully and neatly trim around appurtenances penetrating the ceiling surface providing custom steel trims where necessary. Provide additional support to adjacent ceiling areas as required.
13.3.3 Plasterboard ceilings generally
Comply with BS 8212 subject to any qualifications given below.
The entire suspended ceiling system should be carried out in accordance with the manufacturer’s instructions where appropriate and as directed by the architect where necessary to suit site conditions.
13.3.4 Plasterboard suspension system installation
The installation of the ceiling suspension system and the fixing and finishing of the plasterboard is to be carried out in strict accordance with the manufacturer’s instructions.
a) Install suspension system in accordance with approved shop drawings.
b) Secure 75 x 75mm hardwood perimeter trim, perimeter channels and soffit cleats as required avoiding the use of, or interference with, any mechanical or electrical device already in place.
c) Ensure entirely assembly, including timber framing where necessary, is firmly fixed and forms a rigid assembly ready for the installation of the
plasterboard.
d) Frame around and provide rigid support to any ceiling mounted fitting, including access panels where required.
e) The acceptable dimensional tolerance for the assembly is 3mm in 3m.
13.3.5 Plasterboard installation
a) The ceiling should be set to the heights shown on the Drawings and should be true and level.
b) Secure plasterboard using approved self-tapping galvanised screws to metal framework at maximum 230mm centres. Neatly trim around ceiling mounted fixtures and other appurtenances penetrating the ceiling. Provide and fix trims as necessary.
All end joints shall be broken over successive courses and located over a support. Ends of sheets shall be tightly butted and edges lightly butted, the sheets being fixed at 100 mm intervals. Fixings shall be not less than 9 mm from edges of sheets. Where sheeting has been cut, fixings shall not be less than 18 mm from cut edges. Fixings shall be well driven home with heads slightly below the surface, but shall not break the paper. Punches shall not be used. All angles between bulkheads and ceiling and all vertical angles shall be reinforced with 90 mm wide jute scrim set in plaster and trowelled flat.
c) Finish all fixing devices, taped joints and edges as recommended by manufacturer to leave a perfectly smooth clean and neat finish without defects ready for painting.
13.3.6 Painting / Finish
Proceed with painting of ceiling surface as soon as possible after installation.
Refer “Painting Section” for painting specification.
Stone wool ceiling to be finished by cleaning only. If painting is required, special acoustic paint supplied by the manufacturer to be used.
13.3.7 Completion of suspended ceilings
Ensure the completed ceilings are thoroughly clean and to the satisfaction of the Engineer before handover.