How to Seal the Roof of a Prefabricated Concrete House

The sealing of a prefabricated concrete house roof should be selected based on the roof type, budget, and waterproofing requirements. Common methods and construction points are as follows:

I. Sealing Sloped Roofs with Precast Concrete Panels (Recommended for Sloped Roof Scenarios)

Characteristics: Made of reinforced concrete, these panels offer high strength and durability, suitable for drainage and heat insulation needs on sloped roofs.
Construction Steps:

1. Measurement and Planning: Determine the laying direction and quantity of precast panels based on the sloped roof dimensions, prioritizing panels with drainage holes.
2. Foundation Preparation: Ensure the roof structure is flat and sturdy, reinforcing load-bearing beams or columns if necessary.
3. Laying and Sealing: Align the panel joints tightly and fill the gaps with waterproof glue to prevent water leakage.
4. Fixing and Inspection: Secure the panels with bolts or welding, and conduct a waterproof test (such as a water spray test) upon completion.
   Applicable Scenarios: Self-built houses with sloped roofs, projects requiring rapid drainage and a moderate budget.

II. Sealing Flat Roofs with Precast Panels (Preferred for Low-rise Self-built Houses)

Key Points:

1. Material Selection: Choose standard precast panels with a thickness of ≥12cm to ensure the load-bearing capacity meets design requirements.
2. Laying and Reinforcement: After aligning the panels, fill the gaps with 1:2 cement mortar and level the surface; if the panel span is large, add a steel mesh to enhance overall stability.
   Advantages: Short construction period and low cost, suitable for self-built houses of 2 stories or less, but attention should be paid to joint waterproofing.

III. Waterproofing Treatment (For Leak Repair)

Core Issue: Leaks often stem from panel joint cracks rather than damage to the precast panels themselves.
DIY Construction Steps:

1. Base Preparation: Clean the roof surface of dust and moss, and use an angle grinder to cut V-shaped grooves along the panel joints (width 12cm, depth 12cm).
2. Sealing and Filling: Fill with polyurethane sealant, compact and smooth it, and reserve space for expansion.
3. Reinforcement Layer Construction: Apply non-woven fabric or polyester fabric to form a 'one-fabric-two-coat' structure, preventing the waterproof layer from being pulled apart.
4. Overall Coating: Apply acrylic or single-component polyurethane waterproof coating in two cross-coats, with a thickness of ≥1.5mm.
5. Water Closure Test: After curing for 24 hours, conduct a water test to confirm no leakage.
   Professional Solution: It is recommended to use SBS modified asphalt waterproofing membrane (lifespan 8~12 years) or a composite process of high-elastic coating + polyester fabric.

IV. Precautions

1. Safety Protection: When working at heights, wear a double-hook safety harness and set up load-bearing scaffolding; construction without protection is strictly prohibited.
2. Structural Load-bearing: Before construction, confirm that the roof structure can bear the weight of the precast panels and conduct reinforcement design if necessary.
3. Waterproofing Focus: Elastic sealing materials must be used at the joints to prevent cracking due to thermal expansion and contraction.

Summary: For sloped roofs, precast concrete panels are preferred for sealing; for low-rise self-built houses, standard precast panels can be used for the roof; leak issues require targeted repair. All solutions must strictly follow construction specifications to ensure safety and durability.