Under the current regulatory requirements, it is explicitly stipulated that the installation of floor drains must be level and secure with no leaks around the edges; the floor drain water seal must be no less than 50mm; and the floor drain should be set at a lower position on the ground near water-spraying appliances, with the top surface of the drain being 2mm to 5mm below ground level. Currently, due to design concepts and pricing factors, some new, practical, and easy-to-install floor drains have not been widely promoted and used. The majority of projects on the market still commonly use floor drains made of simple, inexpensive PVC or cast iron. The drawbacks of these two types of drains are that, during installation, insufficient coordination between the construction and installation units, combined with the difficulty in accurately positioning the ground level of the bathroom floor before the installation of the drain, often results in significant height differences after the tiles are laid, causing considerable difficulties in the later stages of construction for rework and adjustments, and also wasting manpower, materials, and financial resources. Based on practical field experience in recent years, the following instructions are provided on how to adjust the installation of these two types of drains below the ground level, hoping to encourage fellow professionals.
1. Cast Iron Drain Installation and Adjustment
Due to the cast iron drain's bell-shaped structure, the drain cover is separate from the water seal bowl. As long as the drain is below the decorative ground level, the process is relatively simple.
1) Determining the Waste Outlet Elevation. The installation height of the waste outlet bowl should ideally be level with the floor of the layer above, as this prevents the accumulation of water on the upper layer, reduces the likelihood of leakage, and avoids mold formation due to long-term dampness within the bathroom floor.
2) Plugging the Hole. After the floor drain installation, the hole must be sealed properly, ensuring a clear distance of at least 20mm between the drain edge and the hole edge to avoid affecting the grouting quality. The specific method is as follows: first, place a wooden board supported by wires at the bottom of the hole, ensuring it is tightly sealed against the pipeline and the floor joist. Clean the hole thoroughly, moisten it with water, and then fill it with mortar. The filling should be done in two stages for better compactness of the pour.
3) Handling Method for Floor Drains Lower Than Decorative Surface. During the initial ground leveling of civil construction, installers should promptly insert a short piece of PVC pipe with the same diameter as the floor drain at the drain opening, with the height being 3mm to 5mm above the leveling layer. After the leveling layer has cured, installers can cut off the excess part based on the thickness of the tile laying, leaving the drain cover about 2mm below the decorative tiles.
4) Setting the Drainage Hole Coordinates. It is preferable to locate the drainage hole coordinates at the center of the bathroom, as this allows for easier slope finding and meets the requirements for tile layout.
5) Protection of floor drain openings. Generally, there is a considerable time between the completion of floor drain installation and the final project completion, thus timely and tight sealing of the pipe openings is essential. After the floor drain installation is finished, the installer should immediately seal the drain opening to prevent mortar or debris from falling into the pipe, which could lead to clogging or accumulation, causing poor drainage or difficulty in clearing. Additionally, both civil construction and installation personnel should have a strong awareness of product protection and professional quality.
