How to Make the Roof of a Prefabricated Concrete House

The construction of the roof of a prefabricated concrete house requires the sequential completion of core steps such as roof structure construction, roofing installation, and waterproofing treatment, with targeted measures taken for different structural types. Details are as follows:

I. Roof Structure Construction

Select the roof type based on the building's purpose. Common structures include cast-in-place concrete roofs, light steel structure roofs, wooden structure roofs, and arch roofs.

• Cast-in-place Concrete Roof: Ensure that the formwork is molded in one piece, and the steel bar diameter is not less than 12 millimeters to guarantee load-bearing capacity. After pouring, continuous curing for 7 days is required, maintaining moisture by covering with moisture-retaining materials or spraying water to prevent cracking due to rapid water evaporation.
• Light Steel Structure Roof: Precisely match the spacing of the joists with the size of the tiles to avoid installation instability or leakage due to dimensional deviations. The joist spacing is usually designed according to the tile specifications; for example, corrugated tiles should be aligned with the peak spacing.
• Wooden Structure Roof: The slope should be controlled between 35-45 degrees to facilitate natural rainwater drainage. The wood should be treated in advance for insect and decay resistance, such as by applying tung oil or preservatives, to extend its service life.
• Arch Roof: Accurately calculate the arc to ensure uniform force on each layer of bricks. During construction, wait for the cement of the lower layer of bricks to fully solidify before proceeding with the upper layer to avoid structural deformation and collapse.

II. Roofing Installation

Select the installation method based on the material type. Common materials include prefabricated concrete tiles and cement tiles.

• Prefabricated Concrete Tiles: Rely on the precise interlocking of the tile protrusions and rib beams to ensure structural stability. During installation, check the fit between the tiles and rib beams to avoid water leakage due to gaps.
• Cement Tiles:
  1. Mold Making: Use a semi-circular tile mold to create a raised wavy structure. Fix it with wooden strips, pour cement mortar, spread it evenly, and smooth it to make cement steps.
  2. Molding Process: Shovel the cement into the mold and smooth it out, then press it against the cement surface to form wavy tiles. After completing a whole row, use a knife to hollow out the middle part of the circular cement to reduce weight and enhance drainage performance.

III. Waterproofing Treatment

Strictly follow a six-step process to ensure long-term waterproofing of the roof.

1. Base Layer Cleaning: Remove the old waterproof layer, fill in cracks and pits, and plan the drainage slope (usually not less than 2%).
2. Overall Coating: Apply the waterproof coating evenly, paying special attention to detailed brushing at pipe openings and corners. For wall corners and internal corners, adopt the 'one-cloth-three-coats' process (i.e., apply one coat of coating, lay polyester fabric, and then apply two more coats of coating).
3. Node Reinforcement: Add a polyester fabric reinforcement layer at easily leaking parts such as the junction between the roof and the wall and the base of pipes.
4. Full-coverage Polyester Fabric: Cover the roof with polyester fabric and impregnate it with coating, pressing it firmly to ensure no bubbles or wrinkles.
5. Surface Coating and Closed Water Test: After drying, apply the third coat of surface coating and conduct a 24-48 hour closed water test to observe for any leakage.
6. Mortar Protective Layer: After passing the inspection, pour a 2-centimeter-thick cement mortar protective layer to prevent damage from sun, rain, and human activities.