How to Construct a Bathroom in a Prefabricated House

The construction of a bathroom in a prefabricated house requires comprehensive control over material selection, waterproofing, pipeline testing, and foundation construction. The specific methods are as follows:

1. Selection of Lightweight Materials
The load-bearing capacity of the prefabricated panels in a prefabricated house is limited. Therefore, for the partition walls of the bathroom, it is essential to prioritize lightweight yet structurally stable materials, such as aerated concrete blocks, light steel keel gypsum boards, or hollow bricks. It is recommended that the material thickness does not exceed 120mm. These materials can fulfill the partition function while avoiding deformation or cracking of the prefabricated panels due to excessive self-weight. During construction, ensure that the materials are firmly connected to the prefabricated panels, using specialized adhesives or expansion bolts for fixation.

2. Waterproofing Treatment
Waterproofing is a core aspect of bathroom construction and should be implemented in three steps:

• Base Layer Treatment: Thoroughly clean the ground and wall base layers to remove impurities such as oil stains and floating dust. First, apply a coat of waterproofing agent mixed with cement mortar to the base layer. After it has completely dried, apply another coat of waterproofing agent mixed with cement paste to enhance the base layer's impermeability.
• Waterproof Layer Construction: It is recommended to adopt a combined process of "permeable leveling adhesive + polyurethane waterproof coating". First, apply the permeable leveling adhesive to fill the micro-pores in the base layer, then evenly apply the polyurethane waterproof coating (thickness ≥ 1.5mm) to form a continuous waterproof membrane. The use of membrane or polymer waterproof layers is prohibited because the seams of the membrane are prone to cracking due to deformation of the prefabricated panels, and the durability of the polymer waterproof layer is insufficient. If using a waterproof membrane, ensure that the base layer is dry, use a flame gun to heat and tightly bond the membrane seams, and avoid sharp objects such as stones from puncturing the membrane during backfilling. Non-woven fabric waterproofing can be used as an auxiliary measure, that is, directly laying non-woven fabric after applying a thin layer of cement mortar to the base layer to enhance the toughness of the waterproof layer.
• Closed Water Test: After the waterproof layer is completed, a 72-hour closed water test must be conducted to observe for any signs of leakage on the ceiling or walls of the floor below. Only after confirming no issues can the next construction step proceed.

3. Pipeline Testing and Installation
After the installation of the drainage and water supply pipes, separate water tests must be conducted:

• Drainage Pipe Testing: Inject water into the pipes and observe the water level changes to check if the pipe slope is reasonable (generally, the slope should be ≥ 2%) and if the joints are sealed, ensuring smooth drainage without leakage.
• Water Supply Pipe Testing: Conduct a pressure test (usually with a pressure ≥ 0.6MPa) for more than 30 minutes. A pressure drop of no more than 0.05MPa is considered qualified, confirming that there is no leakage in the pipes before they can be sealed.

4. Ground Elevation and Drainage Pipe Laying
To optimize drainage and waterproofing effects, it is recommended to elevate the entire bathroom floor by approximately 40cm, allowing the drainage pipes to be laid along the exterior walls and reducing the number of pipes running through the interior. The elevated layer should be filled with lightweight materials (such as ceramsite concrete) to avoid increasing the load on the prefabricated panels. When laying the drainage pipes, strictly control the slope and use specialized adhesives or hot-melt connections at the joints to ensure tightness and prevent backflow or odor reflux.