Suitable for open keel ceiling projects using light steel keel, aluminum alloy keel, wooden keel, or similar frameworks, with decorative materials such as gypsum board, metal plates, mineral wool board, plastic board, glass panels, or grating.
1. Material Preparation
Ceiling panels, keels, hanging rods, and other necessary materials.
2. Equipment Preparation
Tools including an impact drill, toothless saw, steel saw, nail gun, planer, screwdriver, plumb bob, angle ruler, level ruler, chalk line, ink fountain, and others.
3. Working Conditions
1. After installing various pipelines and equipment within the ceiling space, determine the locations for lights, ventilation openings, and other fixtures.
2. Complete all wet work on walls and floors before installing the ceiling panels.
3. Set up the construction platform framework for roof work.
4. Before large-scale installation of light steel keel ceilings, build a sample room to address arching, light troughs, series boxes, ventilation openings, and other ceiling features. After verification, proceed with large-scale construction.
4. Construction Process and Key Points
The installation sequence for the open keel ceiling is: snap line leveling → install suspension rods → install edge keels → install main keels → install secondary and cross bracing keels → install decorative panels.
1. Snap Line
Mark the control line for the ceiling’s lower opening elevation along the walls according to design specifications. Then, mark the hanging points on the ceiling and verify their spacing based on detailed drawings. Ensure the snap lines are clear and accurately positioned. Also, mark the main keel positions on the concrete ceiling, dividing the ceiling center outward, with a maximum spacing of 1000mm. Mark the suspension rod fixing points spaced 900–1000mm apart. If beams or pipelines exceed design specifications, add additional fixing points for suspension rods.
2. Suspension Rod Installation
For inaccessible suspended ceilings, use 6mm diameter rods if the length is under 1000mm, or 8mm rods if longer. For accessible suspended ceilings, use 8mm rods if under 1000mm, or 10mm rods if longer. One end of the rod is welded to a corner bracket (with aperture size matched to the rod and expansion bolt), and the other end features a threaded section or welded finished screw rod. All rods are treated for rust prevention and fixed to the floor with expansion bolts.
Rods must be straight, and the distance between suspension rods and the main keel end should not exceed 300mm; otherwise, add extra rods. Adjust suspension rods when encountering equipment and add rods for ceiling lighting fixtures, air vents, and maintenance openings.
3. Edge Keel Installation
Install edge keels following design requirements. Fix L-shaped galvanized light steel bars or aluminum materials to pre-embedded wooden blocks on walls or columns using self-tapping screws along the horizontal keel line. For concrete walls or columns, use nails with spacing not exceeding that of the secondary ceiling keel.
4. Main Keel Installation
The main keel is typically suspended from the rods with spacing between 900–1000mm. For large, shaped ceilings, weld the shaped parts into a frame using angle or flat steel, securely connecting to the floor slab.
Keel spacing and cross-section must meet design criteria. Main keels include light steel and T-shaped types. TC50 and UC50 medium keels are common for suspended ceilings, spaced 900–1200mm between hangers; TC38 and UC38 small keels are also used with similar spacing. Main keels should run parallel to the room’s length and have a camber of 1/200 to 1/300 of the span. The cantilever section must not exceed 300mm; otherwise, add suspension rods. Keel extensions are made by docking with staggered joints. After main keel installation, level and adjust for position and flatness before installing secondary keels.
5. Secondary and Cross Bracing Keel Installation
Install secondary keels closely against the main keel, with spacing based on the cover panel specifications. When attaching secondary keels to the main keel, use T-shaped galvanized iron sheet connectors, ensuring both ends rest on the L-shaped edge keel’s horizontal flange. Cross bracing keels connect at both ends to full-length keels using connectors. Connections are typically made with clips, sometimes with pop rivets. Position and flatness are carefully calibrated, with connectors staggered.
6. Decorative Panel Installation
Ensure edges of decorative panels interlock properly, matching patterns precisely. Avoid overly tight or loose fits between panels and keels. When using the shelving method, leave an installation seam gap not exceeding 1mm on each side. Glass ceiling panels’ overlap width should meet design requirements, using flexible connections where needed.
6.1 Decorative Gypsum Board Installation: Use aluminum alloy T-shaped keels. After confirming keel installation, place the gypsum boards on the shelf and gently tap edges with a small rubber hammer for secure fitting.
6.2 Mineral Wool Decorative Sound-Absorbing Panels Installation: Typically available in 600mm × 600mm or 600mm × 1200mm sizes. Panels are placed directly on the keel. Ensure correct positioning and alignment of arrows and chalk lines on the panel backs for consistent pattern integrity.
6.3 Silicon Calcium and Plastic Board Installation: Usually 600mm × 600mm, these panels are placed directly on the keel. Align arrows on the panel backs with chalk lines to maintain pattern continuity.
5. Quality Standards
According to the “Code for Quality Acceptance of Building Decoration and Renovation Engineering” (GB50210-2001):
1. General Provisions
(1) Formaldehyde content in artificial wood boards must be retested for ceiling projects.
(2) Before keel installation, conduct handover inspections verifying room net height, opening elevations, and elevations of pipes, equipment, and supports.
(3) Wooden suspension rods, keels, and decorative panels must undergo fireproof treatment and comply with fire safety regulations.
(4) Embedded parts and steel suspension rods require rust prevention treatment.
(5) Complete debugging and acceptance of pipes and equipment before decorative panel installation.
(6) Inspect concealed works including pipe and equipment installation inside ceilings and water pipe pressure tests; fireproof and anti-corrosion treatment of wooden keels; embedded parts or tie bars; suspension rod installation; keel installation; and filling material setup.
(7) Distance between suspension rods and main keel ends must not exceed 300mm; add rods if exceeded. For suspension rods longer than 1.5m, install counter supports. Adjust and add rods when encountering equipment.
(8) Heavy lighting fixtures, fans, or heavy equipment must not be mounted on suspended ceiling keels.
2. Main Control Items
6.3.2 Ceiling elevation, size, camber, and shape must meet design specifications.
Inspection method: Visual observation and measurement.
6.3.3 Decorative materials’ type, specifications, patterns, and colors must conform to design requirements. Glass panels must be safety glass or adequately protected.
Inspection method: Visual check, product certification, performance test reports, and acceptance records.
6.3.4 Decorative materials must be securely installed, with overlap width on keels exceeding two-thirds of the load-bearing surface.
Inspection method: Visual, manual, and measurement checks.
6.3.5 Suspension rod and keel materials, specifications, spacing, and connection methods must meet design criteria. Metal keels require anti-corrosion treatment; wooden keels require anti-corrosion and fireproof treatment.
Inspection method: Visual, measurement, product certification, and acceptance records.
6.3.6 Visible keel ceiling installation must be firm and secure.
Inspection method: Hand wrench test and review of concealed work records.
3. General Items
6.3.7 Decorative panel surfaces must be clean, color-consistent, and free of warping, cracks, or defects. Overlaps with visible keels should be smooth and uniform. Pressure strips must be straight and consistent in width.
Inspection method: Visual and measurement inspection.
6.3.8 Positions of lighting fixtures, smoke detectors, sprinklers, air vents, grates, and other equipment on decorative panels should be well-designed and tightly connected.
Inspection method: Visual inspection.
6.3.9 Metal keel joints must be flat, aligned, and color-consistent without surface defects. Wooden keels must be flat, straight, and free of splits.
Inspection method: Visual inspection.
6.3.10 Sound-absorbing materials in the ceiling must meet design specifications, and anti-scattering measures must be applied.
Inspection method: Review of concealed work acceptance and construction records.
Installation tolerances and inspection methods for visible keel ceilings must comply with Table 6.3.11 requirements.
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