Drainage Pipe Diagram for Prefabricated Slab Houses

Currently, a specific diagram of the drainage pipes for prefabricated slab houses cannot be directly provided, but the common layout and design points can be explained in conjunction with the principles of building drainage systems. The design of drainage pipes in prefabricated slab houses must adhere to building drainage codes to ensure smooth drainage, odor and leak prevention, while also taking into account construction convenience and post-construction maintenance needs. The following explains from three aspects: pipe layout, material selection, and key node design.

1. Pipe Layout Principles

The drainage pipes in prefabricated slab houses generally adopt a "gravity flow" design, utilizing the self-weight of sewage to flow from high to low areas. The main drainage pipe is usually laid vertically along the load-bearing walls or corners of the house, while the branch pipes connecting sanitary fixtures (such as toilets, sinks, floor drains, etc.) on each floor are horizontally connected to the main drainage pipe. To reduce noise, drainage pipes should be kept away from quiet areas such as bedrooms and living rooms, and preferably arranged in non-residential spaces like kitchens, bathrooms, or stairwells. For multi-story houses, each floor should have an independent drainage branch pipe to avoid interference between upper and lower floors' drainage, and a inspection port should be set at the bottom of the main drainage pipe for easy post-construction dredging and maintenance.

2. Material Selection Requirements

Drainage pipe materials must possess characteristics such as corrosion resistance, aging resistance, and good sealing. Commonly used materials include PVC-U pipes (rigid polyvinyl chloride pipes) and cast iron pipes: PVC-U pipes are lightweight, easy to install, and cost-effective, making them the mainstream choice for residential drainage; cast iron pipes are heat-resistant and impact-resistant, but heavy and difficult to construct, often used in high-rise buildings or scenarios with strict noise control requirements. Pipe connections should use special glue (for PVC-U pipes) or rubber sealing rings (for cast iron pipes) to ensure tight interfaces and prevent sewage leakage. Additionally, the outer walls of the pipes should be wrapped with insulation materials (such as rubber-plastic sponge) to prevent freezing and blockage in winter due to low temperatures.

3. Key Node Design

1. Trap (Water Seal): A trap should be installed below the drainage outlet of sanitary fixtures, using the water stored in the bend to form a water seal and block the backflow of sewer odors. The water seal height of the trap should not be less than 50mm, otherwise, it may easily fail due to evaporation or air pressure changes.
2. Vent Pipe: The top of the main drainage pipe should extend to the roof to install a vent pipe, balancing the air pressure inside the pipe and preventing negative pressure from forming during sewage discharge, which could destroy the water seal by suction. The outlet of the vent pipe should be kept away from doors and windows to avoid odor backflow.
3. Cleanout: A cleanout should be installed every 6-8 meters along the horizontal drainage pipe for easy cleaning of deposited debris inside the pipe. The cleanout should face a direction that is easy to operate (such as the outside of a wall) and be equipped with a removable cover plate.

For specific diagrams, it is recommended to contact professional architectural designers or decoration companies to customize a drainage plan based on the house structure (such as the span of the prefabricated slabs, the location of the bathroom, etc.) and refer to the "Building Water Supply and Drainage Design Standard" (GB 50015-2019) for construction acceptance.