Methodology False Ceiling Works
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Methodology of False Ceiling in General: The false ceilings are required for different reasons, namely,
i) In sloping roofs, to provide a flat and even appearance and prevent birds to sit and nest,
ii) To improve acoustics of the room, hall,
iii) To reduce volume of air conditioning in case of high rooms
iv) To reduce heat conduction from flat roofs or
v) To cover electric cables, wires and other service pipes etc.
All false ceilings are suspended from the roof, by means of steel wire, or steel strips. The system of framing, suspending, and fixing of frame is similar except the tile material and the material used for the frame. The choice of covering/filling material depends on several considerations like:
Aesthetics, The purpose for use , Availability and cost
Types of false ceiling:
Hessian Cloth False Ceiling: This is cheapest and functional, type of false ceiling and is provided under sloped roofs, of wooden trusses. Here the frame is nailed on the bottom beam of the trusses or hung to the rafters. Hessian cloth is normally available in a roll of width of (), () and (). The cloth should be
real self-edged, on both sides. For a frame of grid, choose the cloth of width. The Hessian cloth quality is measured in weight (Oz’s.). Proper quality for ceiling is cloth of weight, . per sq. yard. The cloth is available in rolls and is stretched from end to end of the room in one panel of width. This way the whole room is covered. The cloth is nailed to the frame. A wooden beading of 25x12 mm is nailed. At the cut end/side of the cloth, an additional length of 50 mm and atself-edges,, 25 mm, is taken which is folded in two layers of 25 mm, and one layer respectively, and nailed. The cloth is given 3-4 coats of lime wash, till it gets a smooth finish.
A.C.Sheet False Ceiling: Asbestos cement plain sheets are light and provide good heat insulation and are fire proof. On painting they get good smooth and shining surface and are therefore a good and cheap material for false ceilings. They are available in sizes 1200×1200 mm, 1200×1800 mm and 1200×2400 mm sheets and in two thicknesses 4mm and 6 mm. The panel size of 1200x1200mm should be chosen for ceiling and any of the sheets with 4mm or 6 mm thickness can be used on steel or aluminum frame. However, if panels are chosen bigger than 1200×1200, or they are to be fixed on wooden frame, 6 mm sheets only be adopted. The joints are covered with a wooden bead of size 25x 12 mm.
Particle Board Ceiling: Particle boards can take very good polish and can be laminated also. They also do not conduct heat and as such protect against heat radiated from the roof. They are available in sizes 1220×2440 and panels of 1220×1220 mm can be conveniently provided.
Gypsum Board False Ceiling: Gypsum board ceilings are provided mostly when the false ceiling is to be covered by P.O.P. This is good insulator of heat and is suitable for air- conditioning requirements. These are available in tiles of 600×600 mm and accordingly the frame has to be made with grid of matching size. Prior to adopting Gypsum board for false ceiling the water proofing of the roof should be doubly checked, as these boards get spoiled by coming in contact with water.
Straw Board False Ceiling: Straw Boards are comparatively light and are also considered better for acoustic improvement, due to their rough exterior. These are also spoiled by coming in contact with water and leakage of roof if any should be thoroughly attended.
P.V.C. False Ceiling: PVC Ceiling has various advantages over other materials namely they are waterproof, Termite Proof, Fire Retardant, Economical, Maintenance free, and is available in various colours shades without any need of Painting & Polishing. These are being manufactured under several trade brands and are supplied along with extruded channels and other sections in P.V.C. for frames.
Types of Frame:
Steel or aluminum frame: The frame work for false ceiling is normally made of Galvanized steel ‘T, section or suitable Aluminum ‘T, section, kept upside down. The load of the frame as also the tiles/panels etc. is primarily taken by the suspenders and the frame provides means of seating the tiles only and support partially, the dead load of tiles, between two suspenders. Normally the tiles/boards are commercially available in size of 600×600 or 1200×1200 mm and accordingly the frame have to be made with a grid size of 600×600 mm or 1200×1200 mm. The frame is hung to the main roof from the suspenders fixed to the original ceiling and also fixed to the wall. Rolled Aluminum ‘T, section of 38×38 mm with a thickness 3.1mm @ 3.45 Kg/m weight, should normally be used. Steel ‘T, section of 40x40x3 mm can also be used The frame is suspended on level adjusting hangers of 2 mm diameter galvanized M.S. wire spaced at a distance of 1200mm center to center, fixed to roof by means of galvanized expansion hold fasteners or hooks 4 mm diameter. The entire frame and angles shall be provided with approved preservative coat, in case M.S. angles and ‘T, are used. The wire, fasteners should be galvanized for protection against corrosion. This is very important, as the humidity above the false ceiling is substantial and false ceiling are known to have sagged due to corrosion of the suspender elements. The ‘T, sections are also supported on the equal angle 40x40x3 mm fixed all around wall, at a decided level, depending upon the height of false ceiling to be kept.
The main ‘T, should run in the shorter dimension of the room, and the cross ‘T, is fixed between the two main ‘T, member using metal screws fixed on the vertical leg of the two ‘T,s, through a right angle cleat made from a flat of 15×3 mm. The length of the legs of the cleat is 50mm.
Wooden frame: Any hard wood like Teak, of 40×25 mm size should be used for making the frame. The runner on the walls, replacing the angle, can be 25×40 mm. The joints and the nails/screws are covered with wooden beading of 25x12mm, with wood screws. X-joint is provided at the junction of main and cross battens.
Fixing of AC Sheet and Hessian Cloth on Wooden Frame: All fixing on wooden frame is done from underside as opposed to Aluminum or steel frame. The fixing is carried out with nails/ wood screws, as required for strong and durable fixing. The Hessian cloth is fixed with Tach nails and the A.C. sheets are fixed on the frame with counter sunk wood screws to the underside of the frame. Where joints are to be covered, the tiles/boards may be spaced 3 to 4 mm. apart. In case the boards, where joints are to be left exposed, the sheets should be butt laid with their edges abutting in moderate contact, but without having to force them into place. For the exposed joints, the outer rows of the screws are placed at centers and about from the edge of the sheet The nails should be counter sunk in the underside of board with a suitable punch. Care shall be taken in driving the nails so that the sheets are not marked by hammer blows.
In the outer rows at edges to be covered by beadings, the screws will be spaced at centers in each row but with the screws staggered. The beadings will then be fixed over the sheets with screws at centers in each row with the screws in the two rows staggered and passing through beading, sheet and framing so that ultimately the spacing of the fixing (nails and screws taken together) in each row will be at centers so far as the sheets and frames are concerned.
Finishing: The exposed side of the board shall be truly level and plane without any local bulges or sags. The joints shall be truly parallel and / or perpendicular to the walls. The width of joints shall be uniform. Care shall be taken to see that the uniformity of colour of the sheets is not spoiled during the fixing operations.
Where the joints are required to be covered, beadings of uniform size, pattern and material shall then be fixed with screws.
Process for installation of Aluminum False Ceiling:
Planning for a Suspended Ceiling
Installing Wall Angles
Locating and Hanging Suspension Wires for Main
T, s and Border CrossT,s
Installing Ceiling Panels
Step 1: Planning for false ceiling:
First, get the exact measurements of the room where the suspended ceiling will be installed. Use special care in measuring any odd – shaped alcoves, bays, etc.
Draw the exact dimensions to scale on graph paper (Fig. 1) then estimate the material required.
Any pattern of 600×600 mm, 600×1200 or a 1200×1200 mm, pattern (Fig. 2) should be selected. The pattern which is selected will determine the material requirements for the ceiling.
For the 600×1200 pattern, decide to install the patterns in a standard or reverse pattern (Fig. 3). Each pattern offers a different appearance.
According to the decision, sketch the layout for the planned ceiling on graph paper. One can use the layout in Fig. 1. Position the
T, s s<a href="http://www.ngxaki.com/2016/10/methodology-false-ceiling/image233/"><img class="alignleft wp-image-659 size-medium" src="http://www.ngxaki.com/wp-content/uploads/2016/10/image233-300x127.png" alt="methodology image233" width="300" height="127" /></a>o that the border patterns at the room edges are equal on both sides and as large as possible. Attempt should be to get end panels more than half the tile/panel.T, s so the border panels at the ends of the room are equal and as large as possible. If you are using a 600×1200 mm pattern, main
It is important to space the cross
T,s will be 1200 mm apart and the crossT,s will be 600 mm apart. For a 600×600 mm pattern, main
T,s and crossT,s shall be at 600 mm apart (Fig. 2).
If the ceiling will be recessed and built-in lighting will be installed, decide where to locate the panels of light and clearly identify them on the drawing.
Step 2 : Installing wall angles:
Determine the exact height at which the suspended ceiling will be installed. Allow a minimum of 75 mm to 100 mm clearance between the existing ceiling and the new false ceiling for installation of the ceiling panels. Additional clearance will be required if light fittings are using recessed in the false ceiling (Fig.4). The ceiling should however be not lower than 2600 mm.
After locating the exact position for the suspended false ceiling, draw a line with using water tube level, completely around the room indicating where the wall angle will be applied (Fig. 5). Don’t assume the original ceiling is level, use a water level tube for accuracy.
Fix the wall angles securely to the wall at all points. Nail them firmly to studs, or use screw anchors or other masonry fasteners on brick or masonry walls (Fig. 6).
Position the wall angle so that the bottom flange rests on the level line drawn on the wall.
Overlap the wall angle on inside corners (A, Fig. 7), and miter the wall angle on outside corners (B, Fig. 7). Cut any needed angles with metal cutting snips or a hacksaw.
Step 3 : Locating & hanging suspension wires for main ‘T’s:
If recessed light fittings to use in false ceiling, install the wiring before putting the suspension wires in place .
For recessed lighting, 600×600 mm or 600×1200 mm drop-in lighting fixtures can be used, which are specially designed for this purpose. One can also use center fluorescent light fixtures over the panels and additional cross `T, s will have to be fixed in the frame matching the light fixtures if the fixtures are smaller than the standard panel size.
Depending on the weight of the light fixture, one may decide to strengthen the suspenders near the fixture.
Refer to sketch of the room for the location of all main ‘T,s (Fig. 1). Main ‘T,s should always run at right angles to the longer side of the room.
Locate the position of each main ‘T, by stretching a tight line dori from the top edge of the wall angle on all sides of the room at each position where the main ‘T, s are to be placed (Fig. 8).
Fix expansion hold fasteners on the original ceiling, at the junction of main ‘T, with cross ‘T, at 1200 mm spacing in both directions, the first one being at first row of junctions, which may be less than 1200 mm. Drill a 3.15 mm diameter hole in the vertical leg of the main ‘T, at each junction for fixing the suspender wire.
Cut the suspension wires to the proper length. The wires should be 300 mm longer than the distance between the old ceiling and the new guideline string stretched to indicate the position of each main ‘I s,
Locate the first suspension wire for each main ‘T, directly above the point where the first cross ‘T, meets the main ‘T,. Check the original sketch of the room to determine this location.
Be sure the suspension wires are securely fastened. Apply them to the ceiling with drilling and using expansion hold fasteners (Fig. 9).
Attach a suspension wire every 1200 mm along the level guideline (Fig. 10). Stretch each wire to remove any kinks and make a 90° bend where the suspension wire crosses the level line.
Step 4 : Installing main ‘T’s:
38X38x3 mm Aluminum ‘T, sections are available in lengths of 5.85 m and should not be required to be extended in most cases. If required they can be spliced
using a splice plate of 1.8 mm from both sides duly fixed by counter sunk metal screws, alternately from either side.
Cut the ‘T, equal to the width of the room where the main ‘T, will span. Ihe length should be reduced by 6 mm to account for thickness of wall angles.
The head of ‘T, is cut for a length of 37 mm on both ends by hack saw, to leave the web only intact to sit on the angle evenly as seen from the inside the room. Gas cutting can also be done but the welder should be skilled to obtain a perfect straight and even cut.
Two no. holes of 3.15 diameters are drilled at the sawn stub at each end to receive the cleat as described below.
Mark the junction points with cross ‘T, on the full length of main ‘T,. Fix a cleat (100x20x3 mm, strip bent at 90 degrees to give an angle cleat 50x50x3 mm and 2 holes are drilled on both legs suitable for 3.15 mm metal screw) at each junction point on one side, staggered from center line, by 1.6 mm, to accommodate the cross ‘T,. Similar cleat is to be fixed on other side of vertical leg of ‘T, to receive cross ‘T, from adjacent panel. Each cleat is to be fixed with 3.15 mm metal screws. Similar cleat is also fixed at the two stub ends of the main ‘T,. A 3.15 mm diameter hole is drilled on the vertical leg of main ‘T, between the two cleats 10 mm below the top, to receive the suspender wire.
Install the main ‘T, on the wall angles and simultaneously fixing the suspenders.
Install the main tees so that they are all level with the wall angle already mounted. Use a long level for this.
Step 5: Installing cross ‘T’ & Border cross ‘T’
Cross ‘T, are prepared by cutting to correct size after measuring the actual spacing of the main ‘T,s. Drill two holes at both ends at the appropriate location to fix with the cleat on the main ‘T,. Border cross ‘T, are installed between the wall angle and the last main tee.
Step 6: Installing ceiling panels:
The final main and cross
T, arrangement will look similar to Fig. 12.<img class="size-medium wp-image-670 alignleft" src="http://www.ngxaki.com/wp-content/uploads/2016/10/image246-300x140.png" alt="image246" width="300" height="140" /> The top part of the illustration shows an arrangement of a 600x1200 mm layout, while the lower half shows main and crossT,s arranged for a 600×600 mm layout. Place the ceiling panels into position by tilting them slightly, lifting them above the framework and letting them fall into place.