Toilet Mobile Sunken Box

The toilet mobile sunken box is usually related to the renovation of sunken bathrooms, and attention should be paid to the slope of pipes, backfill materials, and secondary drainage design to ensure smooth drainage and prevent leakage issues.

I. Core Purpose and Advantages of Mobile Sunken Boxes

The core purpose of a mobile sunken box is to provide space for pipe layout modification by adjusting the height of the bathroom's structural layer (usually sinking by 40cm). The advantage of a sunken bathroom is that the toilet can be repositioned without damaging the floor slab, as the drainage pipes can be directly moved within the sunken box to flexibly adjust the positions of sanitary fixtures. However, it should be noted that pipe movement must meet slope requirements: the height of the pipe should decrease by 1-2cm per meter to ensure that sewage naturally flows towards the main drainage pipe. If the slope is insufficient, the slow flow of sewage can easily lead to toilet blockages or poor drainage. During construction, a level should be used to accurately measure the height difference to avoid subsequent problems caused by calculation errors.

II. Selection and Prohibitions of Backfill Materials

The backfill material for the sunken box directly affects the waterproofing performance of the bathroom. It is recommended to use lightweight materials with low water absorption, such as expanded clay or foamed cement slurry. Expanded clay has multiple pores inside, which can effectively absorb moisture and reduce the load on the floor slab; foamed cement slurry has the characteristics of strong integrity and good moisture resistance. It is strictly prohibited to use construction waste (such as broken bricks and concrete blocks) for backfilling. Such materials have sharp edges and corners that can easily damage the waterproof layer, and their increased weight after water absorption may cause the floor slab to crack. At the same time, the gaps between construction waste can easily accumulate water, and the upward diffusion of moisture can cause ground water seepage and wall dampness.

III. The Key Role of the Secondary Drainage System

The bottom of the sunken box must be sloped (with a slope of ≥2%) and equipped with a secondary drainage floor drain. The slope guides the accumulated water in the sunken box towards the floor drain, and the secondary drainage floor drain can discharge the leaked water into the main drainage pipe, preventing the accumulated water from soaking the sunken box for a long time. If no secondary drainage is provided, the accumulated water in the sunken box will seep into the lower floor through weak points in the waterproof layer (such as the roots of pipes), causing disputes with neighbors. During construction, it is necessary to ensure that the floor drain opening is lower than the plane of the sunken box bottom, and use a filter screen to prevent blockages from debris. Regular cleaning should be carried out to maintain smooth drainage.

IV. Construction Process and Acceptance Points

The construction of a mobile sunken box should follow the process of "base treatment → pipe laying → slope testing → backfill material filling → waterproof layer construction → closed water test". After pipe laying, a water flow test should be carried out to confirm no leakage before backfilling; the backfill layer should be compacted in layers to avoid local settlement; the waterproof layer should be painted to a height of more than 30cm on the wall, and a 48-hour closed water test should be carried out to observe whether there is water seepage on the ceiling of the lower floor. Only after passing the acceptance can the floor tile laying be carried out.