Pre-embedded Conduit in Prefabricated Houses

The pre-embedded conduits in prefabricated houses should be scientifically designed and constructed according to their intended use, location, and regulatory requirements. The key points are as follows:

I. Definition and Core Purpose of Pre-embedded Conduits

Pre-embedded conduits are pipes installed in advance during construction, primarily used for concealed installation of water supply, drainage, heating, and electrical systems. Their core purpose is to avoid damaging the structure through later trenching, enhancing construction efficiency and safety. In prefabricated houses, pre-embedded conduits must be installed simultaneously with the main building structure to ensure reasonable wiring layout and compliance with regulations.

II. Pre-embedding Points at Different Locations

1. Pre-embedding in Floor Concrete

   • Timing: Pre-embedding should be completed after the floor reinforcement bars are tied and before concrete pouring.
   • Material Selection: PVC pipes with good flexibility are preferred for their ease of bending and corrosion resistance.
   • Fixing and Protection: After pre-embedding, the conduit should be fixed to the reinforcement bars with wire, and the junction box should be filled with waste paper to prevent concrete infiltration.
   • Wiring Design: Mainly pre-embed conduits for ceiling lights, with other wires (such as network cables) mostly laid beneath floor tiles.

2. Pre-embedding in Walls

   • Method: In rural self-built houses, wall conduits are often installed by cutting trenches later rather than pre-embedding directly.
   • Trenching Specifications: Trenches should be about 4 cm deep and kept parallel or perpendicular; conduits should be embedded 0.5 cm below the wall surface to reduce cracking risk.

III. Differences in Pre-embedding for Lighting and Socket Wires

1. Pre-embedding of Lighting Conduits

   • Roof Layout: Minimize the number of roof junction boxes to avoid affecting the tensile strength of reinforcement bars.
   • Wiring Design: Lighting conduits in walls should turn at the roof, with junction boxes in each room extending from a distribution box. Wiring routes should be planned in advance.

2. Pre-embedding of Socket Wires

   • Underground Installation: Socket conduits are recommended to be laid underground to reduce wall damage; if underfloor heating is installed, conduits should be lowered accordingly.
   • Introduction Method: Only the area where the wire box is introduced into the wall needs to be cut, without extensive trenching.

IV. Key Construction Specifications and Precautions

1. Size Limitations: The outer diameter of pre-embedded conduits in floor slabs should not exceed one-third of the slab thickness, with a parallel spacing of ≥25 mm and a clear distance of ≥30 mm for fire protection electrical conduits.
2. Waterproofing: Pipes passing through exterior walls or roofs of basements should use rigid waterproof sleeves, sized 2-3 numbers larger than the actual pipe, with a waterstop ring made of 5-8 mm steel plate.
3. Secondary Pre-embedding: When trenching is required on masonry, the trench width and depth should be 5-10 mm larger than the pipe diameter and protected with M10 or higher cement mortar.
4. Finished Product Protection: Conduit ends should be sealed for protection, and junction boxes should be positioned and reinforced to prevent concrete slurry infiltration.
5. Functionality First: The principle for pre-embedding water and electricity conduits is to ensure that "wires can be threaded through later," without excessive consideration for aesthetics.