How to Make Prefabricated Panels for the Roof of a Matching House

The construction of prefabricated panels for the roof of a matching house should follow standardized procedures, with core steps including preliminary preparation, construction of foundation beams and support systems, and handling of special scenarios, as detailed below:

I. Preliminary Construction Preparation

1. Material Selection and Inspection

   • Select pre-stressed hollow prefabricated panels that comply with the GB/T 14040-2019 standard, determining panel types (widths of 500mm/600mm and thicknesses of 120mm/150mm) based on roof spans (3m-6m) and load requirements.
   • Inspect the prefabricated panels' certificates of conformity and mechanical performance reports, focusing on identifying defects such as cracks, chipped corners, and exposed rebar; supporting materials must meet the following requirements:
     • Rebar: HRB400 grade (main reinforcement for beams), HPB300 grade (stirrups);
     • Concrete: P·O 42.5 grade cement, medium-coarse sand (silt content ≤3%), crushed stone (particle size 5-25mm, silt content ≤1%).

2. Equipment Configuration

   • Lifting equipment: Use a 2t chain hoist with a gantry frame for single panels weighing ≤1.5t; for spans ≥5m, an 8t or larger truck-mounted crane is required.
   • Concrete construction equipment: Forced mixer (capacity ≥350L), vibrating rods (φ50mm/φ30mm), and plate vibrators.

3. Technical Preparation

   • Detail the drawings to clarify the layout of prefabricated panels, beam elevations, and joint details, adjusting panel joint widths to suit lifting accuracy.
   • Conduct on-site layout and positioning, marking beam position lines, installation control lines, and elevation control points, and setting permanent benchmarks (accuracy ±5mm).

II. Construction of Foundation Beams and Support Systems

1. Foundation Beam Pouring

   • Formwork engineering: Use 15mm-thick film-faced plywood with wooden battens spaced ≤300mm apart; secure beam side formwork with tie bolts (spacing ≤600mm).
   • Rebar tying: Main reinforcement should be double-sided lap-welded (length ≥5d), with stirrup encryption zones set according to design requirements.

2. Prefabricated Panel Installation

   • During lifting, maintain a lifting angle of ≥60°, using dedicated rigging and shackles to avoid collisions.
   • After installation, fill panel joints with M15 mixed mortar (cement:sand:lime paste = 1:5:0.8) to ensure compactness.

III. Handling of Special Scenarios (e.g., Prefabricated Panel Ceilings)

1. Cut holes 80mm long and 40mm wide in the holes of circular-hole panels, inserting 200mm-long, 14mm-diameter rebar.
2. Fabricate 40mm×40mm wooden blocks, 150mm long, and securely tie them to the rebar with No. 8 galvanized wire.
3. Connect the main keel to the wooden blocks via hangers, avoiding damage to the pre-stressed rebar in the circular-hole panels.

Precautions: Prefabricated hollow panels have poor overall integrity and are gradually being replaced by cast-in-place structures in modern construction, though they may still be used in rural areas. Construction must strictly adhere to specifications to ensure material quality and lifting safety.