How to Construct the Roof of a Prefabricated Panel House

The construction of the roof for a prefabricated panel house can be carried out according to the following steps, strictly adhering to design specifications and safety requirements:

1. Pre-construction Preparation

• Design Confirmation: Clarify the roof dimensions, slope (usually 2%-5%), and specifications of the prefabricated panels (such as length 1.2-6 meters, width 0.3-1.2 meters) based on the house design drawings.
• Material Preparation: Calculate the quantity of concrete prefabricated panels (considering the loss rate), and prepare steel bars (diameter 6-12 millimeters), waterproof coatings (such as polyurethane or asphalt-based materials), cement mortar, etc.
• Tools and Safety: Equip with steel bar cutters, spirit levels, plastering tools, scaffolding, and warning signs. Ensure good ventilation at the construction site and no accumulation of flammable materials.

2. Determine the Roof Starting Point and Slope

• Use a spirit level and laser distance meter to mark the highest and lowest points of the roof, and snap a reference line with a chalk line or ink fountain to ensure that the slope error does not exceed ±1%.
• The slope design should take into account both drainage efficiency and structural stability. Flat roofs should be equipped with drainage outlets or gutters.

3. Lay the Steel Bar Mesh

• Bind the steel bar mesh according to the design requirements. The intersections of the main bars and distribution bars should be firmly tied with iron wires, with a spacing usually of 150-200 millimeters.
• The steel bar mesh should be welded and fixed to the roof ring beams or embedded parts in the walls to prevent displacement. The thickness of the concrete cover for the steel bars should be ≥15 millimeters.

4. Lay the Concrete Prefabricated Panels

• Cleaning and Waterproofing: Clean the dust on the panel surface, apply a waterproof coating (thickness ≥1 millimeter), and lay the panels after drying.
• Installation Specifications: Start laying the panels one by one from one end of the roof. Control the gap between panels at 10-15 millimeters. Set expansion joints every 6 meters (width 20-30 millimeters) and fill them with asphalt hemp or foam boards.
• Fixing Method: Fill the gaps with 1:3 cement mortar or use special connectors for fixing to ensure a tight combination between the panels and the steel bar mesh.

5. Plastering and Leveling

• Use 1:2.5 cement mortar to plaster the panel surface twice: the first time to level the gaps and the second time for overall plastering, with a thickness of 15-20 millimeters.
• After plastering, use a straightedge to scrape it flat. After initial setting, use a wooden trowel to roughen the surface to prevent cracking.

6. Curing and Waterproofing Treatment

• Curing: After plastering, cover the surface with plastic film or straw mats, water it 3-4 times a day, and continue for 7-14 days to keep the surface moist.
• Waterproof Layer Construction: After the curing period is over, apply two coats of waterproof coating (total thickness ≥2 millimeters), or lay SBS modified asphalt membrane with an overlap width of ≥100 millimeters and seal the edges tightly.

Key Precautions

• The concrete mix ratio should meet the C25-C30 strength standard. Avoid excessive vibration during pouring to prevent displacement of the prefabricated panels.
• The construction temperature should preferably be between 5-35℃. Construction should be suspended in rainy or snowy weather and covered for protection.
• Regularly check the stability of the scaffolding. Construction personnel should wear safety helmets, non-slip shoes, and safety belts.