Gypsum Board Ceiling for Prefabricated Panel Houses

When installing gypsum board ceilings in prefabricated panel houses, it is crucial to focus on anti-cracking details. Standardized construction and structural optimization can effectively enhance ceiling stability.

I. Characteristics of Gypsum Board Ceilings and Main Causes of Cracking

Gypsum board, primarily made of building gypsum, is lightweight, strong, and offers excellent sound insulation, thermal insulation, and fire resistance. It is fixed using wooden or light steel keel frames. Cracking mainly arises from two factors:

1. Shrinkage Issues: Differences in shrinkage rates between materials (e.g., gypsum board, keel, and walls) after solidification, if not compensated for, can lead to cracks at joints or along side walls.
2. Uneven Force Distribution: Imbalanced force transmission among expansion bolts, keels, and gypsum boards, such as loose keel fixation or improper stress-free installation of gypsum boards, can cause cracking due to tension.

II. Five Key Details for Anti-Cracking in Prefabricated Panel Houses

1. 7-Shaped Corner Treatment
   Gypsum boards at the four corners of the room should be cut into a 7-shape (L-shape) to create a two-sided overlapping structure at the corners. This design disperses stress, preventing traditional right-angle joints from cracking due to concentrated force, especially suitable for the easily deformable structure of prefabricated panel houses.

2. V-Groove at Joints
   Gypsum board joints should be processed into V-grooves with a recommended depth of 1/3 to 1/2 of the board thickness. When filling with joint compound, the V-groove increases material contact area for stronger adhesion and provides buffer space for shrinkage, reducing the risk of horizontal cracks.

3. Staggered Installation of Double-Layer Gypsum Boards
   When using double-layer gypsum boards, they should be fixed in a staggered manner (joints of upper and lower layers offset by more than 300mm) using a light steel keel frame. This structure enhances overall rigidity, disperses deformation stress, and offers better anti-cracking performance than single-layer boards, though it increases costs by about 40% and extends the construction period by 1-2 days.

4. Reinforced Keel Framework
   Main keel spacing should be ≤1.2m, and secondary keel spacing ≤400mm to ensure adequate support density. In prefabricated panel houses, additional keels should be installed at panel joints and fixed with expansion bolts to prevent ceiling sagging and cracking due to joint settlement.

5. Stress-Free Installation Technique
   Gypsum boards should be fixed from the center outward, with self-tapping screws spaced ≤200mm apart and sunk 0.5-1mm into the board surface (avoiding damage to the paper facing). After fixing each board, check flatness with a straightedge to prevent deformation caused by localized stress concentration.

III. Construction Process and Precautions

The construction process should follow the sequence: "measurement and marking → installation of keel framework → installation of gypsum boards → joint treatment." Joint treatment involves filling joint compound in three layers, sanding after each layer dries, and finally reinforcing with kraft paper or fiberglass mesh for enhanced crack resistance. Ambient humidity should be controlled between 40% and 70%, avoiding high or low-temperature operations that may affect material properties.