Ceiling Diagram for Prefabricated Slab Houses

The ceiling of a prefabricated slab house can achieve safety and aesthetics through standardized construction steps and precautions, as detailed below:

I. Construction Steps

1. Snap Line Positioning
   Snap horizontal reference lines around the walls to ensure overall ceiling flatness. Use a laser level or water level for assistance, with an error margin controlled within ±2mm.

2. Fix Edge Joists
   Install edge joists (typically U-shaped light steel joists or anti-corrosion wooden battens) along the wall's horizontal line, with a spacing of ≤600mm. Wooden battens require fire and moisture-proof treatment. Use expansion bolts or steel nails for fixation to ensure a firm connection with the wall.

3. Install Main Joists
   Select main joist specifications based on the span of the prefabricated slabs (light steel joists are recommended to use the 50 series), with a spacing of 900-1200mm. The main joists should be perpendicular to the edge joists and fixed to the floor slab using hangers (φ8 fully threaded steel bars), with a hanger spacing of ≤1200mm and an end overhang of ≤300mm.

4. Reinforce Prefabricated Slab Joints
   Add additional joists at the joints of hollow prefabricated slabs, fixed with "L"-shaped light steel connectors to reduce the risk of ceiling deformation caused by slab joint cracking. Drilling positions should avoid the reinforcing bars in the prefabricated slabs, with a hole diameter ≤1.5 times the diameter of the hanger.

5. Install Secondary Joists and Panels
   Secondary joists should be spaced 300-600mm apart and fixed perpendicular to the main joists. When installing panels, lay them block by block from one end to the other, leaving a 3-5mm gap to accommodate thermal expansion and contraction. Self-tapping screws should be spaced 150-200mm apart and sunk into the panel by 0.5-1mm.

II. Key Precautions

1. Material Selection Priority
   Prioritize the use of light steel joists: Their deformation resistance is more than three times that of wooden joists, making them particularly suitable for environments with significant humidity changes. If wooden joists must be used, select kiln-dried lumber (with a moisture content of ≤12%) and apply fire-retardant coating.

2. Expansion Joint Treatment
   For ceilings with an area >30㎡, set expansion joints every 12m along the length, with a joint width of 10-20mm filled with elastic sealant. Use "L"-shaped whole-panel cutting at corners to avoid cracking caused by right-angle splicing.

3. Sound Insulation Enhancement Solution
   For houses with a ceiling height of ≥3.5m, a composite structure of double-layer gypsum board + 50mm glass wool can be used, achieving a noise reduction coefficient (NRC) of up to 0.85. The spacing of light steel joists should be reduced to 400mm, and cross braces should be added to enhance structural stability.

4. Concealed Work Inspection
   After construction, check the following: the verticality deviation of hangers ≤3mm/m; the spacing error of joists ≤5mm; and the surface flatness of panels ≤2mm/2m. Focus on verifying the reinforcement of joists at the joints of prefabricated slabs.

By strictly adhering to the above process standards, common issues such as cracking and deformation in the ceilings of prefabricated slab houses can be effectively resolved, while also meeting functional and decorative requirements.