Many people may have questions: why does my basement still get damp and moldy even though I have multiple layers of waterproofing?

Actually, moisture resistance does not equal waterproofing. Full wall waterproofing cannot truly prevent water seepage and condensation on the wall! Generally, waterproofing refers to preventing water from seeping into our indoor floors or walls, and waterproofing is to prevent liquid water; Moisture prevention refers to preventing items and spaces from being affected by moisture, mainly targeting air moisture and preventing underground moisture (gaseous water). The daily dehumidification mainly refers to removing excess moisture from the air.

1. Reasons for underground moisture

(1) Moisture sinks downwards, so the lower the position, the more humid it is. The basement is the lowest level of the living environment, and the humidity is relatively concentrated;

(2) The temperature in the basement is lower than the surface temperature. When high-temperature and humid air from the surface enters the basement, the temperature quickly drops, making it easy for condensation to occur and exacerbating the humidity in the basement;

(3) The basement space is relatively enclosed and the ventilation is poor;

(4) The water level in the area where the basement is located is low, and the walls in contact with the outdoor soil will become damp, causing water seepage on the walls and floors;

(5) The basement is close to the moisture source.

2. Misconceptions about waterproofing

(1) Is waterproofing enough for the basement?

The basement is made of thick concrete walls, which are inherently water-resistant and waterproof. If the concrete walls crack and leak, internal waterproofing will not be able to stop it.

(2) Can brushing waterproof materials make it waterproof?

The basement is mainly affected by the moisture regain of condensation water in the air, and applying waterproof materials cannot solve the problem of condensation water regain.

3.How can the basement be waterproof and moisture-proof?

(1) Waterproof construction of walls and floors

(3.1.1) Before waterproofing the walls and floors, snap the lines for construction. The waterproof coating should be uniform and consistent, and the coating thickness should meet the technical performance requirements of the product.

(3.1.2) The waterproof layer on the ground should extend from the ground to the wall, and be 300mm higher than the ground, with neat and obvious color separation lines.

(2) Closed water test

(3.2.1) A threshold stone should be affixed at the entrance.

(3.2.2) Inject clean water and keep it at least 100mm above the edge of the caisson.

(3.2.3) The closed water test time shall not be less than 48 hours.

(3) Hanging treatment of sunken boxes in bathrooms: using 110 pipe support columns to prevent water seepage.

(3.3.1) Bidirectional waterproofing treatment must be carried out: on the basis of waterproofing measures already taken by the developer, secondary waterproofing treatment should be carried out to prevent basement water seepage; In addition to the basement ceiling, floor, and walls, the exterior walls of the basement also need to be waterproofed.

(3.3.2) Moisture proof materials must be selected: The basement is a relatively humid place, so when choosing materials for villa decoration, attention should be paid to selecting materials with good moisture proof effects such as waterproof mortar, wallpaper, vitrified tiles, etc.

At the same time, the temperature difference between the basement wall and the interior can easily lead to condensation. Therefore, in the selection of materials for the basement wall, it is advisable to avoid using ceramic tiles or marble, and to use diatomaceous earth or bricks used for the exterior walls of the house. These materials have high breathability and allow the wall to breathe, which can prevent condensation from occurring.

(3.3.3) Adopting a ventilated and moisture dissipating design: In the basement, air circulation is more important. So the basement of the villa can consider installing an intelligent fresh air system to ensure room temperature and ventilation, which is the best way to insulate and prevent moisture in the basement. Indoor dehumidification can also be carried out using machines such as exhaust fans, air conditioners, or dehumidifiers.

(3.3.4) The focus of basement moisture prevention should be on solving the problem of condensation water in the basement: concrete external waterproofing should be done while insulation layer should be added. Strong and weak electricity in the basement should be carried out on the top surface as much as possible, and the ground should not be slotted. If you can only walk on the ground, do not use galvanized iron pipes, use PVC conduit.

(3.3.5) Due to the lack of light and poor ventilation throughout the year, the basement is heavily humid, and it is necessary to install a fresh air dehumidification system. The fresh air dehumidification system refers to using a fresh air dehumidification host to reach various rooms indoors through pipelines, and dehumidifying or ventilating each room according to the needs of different seasons and time periods. It can achieve central dehumidification and ventilation, and automatically dehumidification according to the humidity value set by the customer, without the need for manual supervision. At the same time, it has the function of purifying the air during circulation and dehumidification, making the air in the living space fresh and reaching the appropriate humidity.

Basement moisture-proof is a systematic project. To create a perfect basement, it is necessary to fundamentally solve the problem, which requires system design from six aspects: waterproofing and drainage, moisture resistance, insulation, dehumidification, ventilation, and materials. Owners need to coordinate with moisture-proof designers, general decoration companies, HVAC companies, and other departments to fully consider all aspects in order to fundamentally solve the problem.