How to Construct a Prefabricated House Roof

The construction of a prefabricated house roof requires systematic waterproofing and structural treatment, with the following specific methods:

I. Waterproofing Practices

1. Key Node Treatment

   • Board End Joints and Crack-Prone Areas: At the joints of prefabricated board ends (e.g., on walls or beams), a 10-centimeter-wide separation joint should be reserved, sealed after being lined with polypropylene. Crack-prone areas such as corners of parapet walls, pipe openings, and drainage outlets should also have gaps reserved, which should be filled with sealing materials after drying.
   • Inter-Board Crack Treatment: First, apply two coats of elastic K11 waterproof coating, then apply a 2-centimeter-thick layer of waterproof mortar. The separation joints should be filled with sealing materials to ensure crack tightness.

2. Overall Roof Waterproofing

   • Material Selection: It is recommended to use SBS modified bitumen waterproof membranes (with good flexibility) or rigid roofs made of fine aggregate concrete (with high durability). The drainage slope should be greater than 2%, and smooth drainage channels should be provided to avoid water accumulation.

II. Construction Techniques

1. Plugging and Caulking

   • Hollow Board Sealing: The holes at both ends of prefabricated hollow boards should be filled with fine aggregate concrete in two pours, with a sealing depth of 300-400mm. The gaps between boards should be grouted in three pours and compacted with a brick trowel to ensure density.

2. Base Layer Treatment

   • Anti-Permeability Enhancement: Prepare a cement slurry of a specific concentration (which can include 107 adhesive) and apply two coats evenly on the board surface and sides to enhance the anti-permeability of the base layer and provide a stable foundation for the subsequent waterproof layer.

3. Construction Steps for Concrete Prefabricated Board Roofs

   • Preparation Stage: Confirm the design drawings (dimensions, slope), specifications and quantity of prefabricated boards, prepare construction tools (reinforcement cutters, level gauges, etc.), and set up scaffolding with warning signs.
   • Reinforcement Mesh Installation: Lay out the reinforcement mesh according to design requirements, ensuring a firm connection with the foundation to enhance the overall structural integrity.
   • Prefabricated Board Installation: Clean the board surface and apply waterproof coating, then lay out the prefabricated boards one by one, maintaining consistent gaps and setting expansion joints to prevent cracking due to thermal expansion and contraction.
   • Plastering and Curing: Smooth the surface with plastering tools. During the curing period, water and shade should be provided in a timely manner to prevent the concrete from cracking due to rapid water loss.
   • Waterproof Layer Construction: After curing, apply or lay waterproof materials to ensure completeness, with a focus on inspecting node areas.

III. Precautions

• Structural Safety: Strictly follow design requirements to ensure that reinforcement layout, concrete mix proportions, and pouring meet standards. Regularly inspect the stability of scaffolding to avoid collapse risks.
• Construction Environment: Maintain ventilation to prevent concrete shrinkage cracking. Protect the site during the curing period to prevent external interference (such as trampling or rainwash).

By following these steps, the waterproofing and structural construction of a prefabricated house roof can be systematically completed, balancing efficiency and quality.