Waterproofing during renovation passes the water-tightness test, but leaks appear after completion—it's a common issue. Though frustrating, there's no need to be overly upset, as many others have faced the same misfortune. So, what causes this and how can it be resolved? Let's delve into it step by step.
Reason 1: Leaking water main pipeline
The pipeline is buried beneath a waterproofing layer. During the renovation, there is almost no water in the above-ground pipes— even during the water-tightness test, the time the pipes are filled with water is relatively short. Therefore, leaks in the above-ground water pipes can only be discovered after normal water usage.
Not only hard to detect, the leak in the upper water pipe is also difficult to resolve. At this point, there's no better method than to dig up the ground to inspect and repair it.
To determine if the leak is due to a broken main water pipe, we need to stop using water in the bathroom, open the pipe valves, and fill the pipes with water. Maintain this state for two to three days and observe; if the leak persists, it can be concluded that there is an issue with the main water pipe.
Note: Conducting pressure tests within the upper water pipes during renovations can prevent issues of leaks in the upper water pipes that go unnoticed.
Reason 2: Drain pipe leakage
The drainage pipes are also below the waterproofing layer, so in case of leakage, water will directly leak down to the floor below, without the protection of the waterproofing layer. During the water-tightness test, the water volume was small, and if there were minor breaches, they might not leak, so we were unable to detect them. However, once the residents move in and the water usage increases, the water begins to seep out slowly.
The drainage pipes are mostly exposed directly to the air (on the ceilings of the downstairs residents), making repairs relatively straightforward.
First, perform extensive drainage indoors and observe from below to locate the leak point. Users can purchase plastic steel mud or waterproof tape and other materials to repair the leak.
Note: Leaking drain pipes will not cause water stains on the ceiling; instead, water will drip directly down the pipe. (Water stains on the ceiling will only occur except for drain pipe leaks.)
Reason 3: Waterproofing layer compromised
The waterproof layer itself is quite fragile; even a slightly sharp material scraping over it can cause damage. Therefore, during the tile installation process, there is a high likelihood of the waterproof layer being injured.
The waterproof layer has been damaged, and it will naturally leak out—If the leakage is not severe, you can purchase an absorbent waterproofing agent yourself, pour it onto the ground, and let it solidify naturally to repair the damage to the waterproof layer (for specific usage instructions, refer to the product manual).
If the crack is large, it's likely that the tile will need to be broken out and re-sealed.
Note: According to national standards, two water-tightness tests are required. Moving the second test to after the bathroom renovation is completed can fully prevent the possibility of damaging the waterproofing layer during construction, thereby minimizing the user's losses.