Taipei Bathroom Waterproofing Project Budget and Water Testing and Pitfall Avoidance Guide

In Taipei and New Taipei Region, aging housing is a common phenomenon. Many homeowners who buy a second-hand house or plan to renovate their old home are most worried about the hidden project "bathroom waterproofing". The bathroom is the area with the highest frequency of water use and the highest humidity in the home. Once the waterproof layer fails, water vapor will penetrate through the gaps in the concrete, causing dripping from the ceiling downstairs, cancer on the walls, and even possible legal prosecution and compensation from neighbors. Among consumer complaint cases in Taipei, neighborhood disputes caused by leaking houses consistently rank among the top three. Therefore, understanding the standard construction methods of bathroom waterproofing projects, a reasonable construction budget, and the necessary water testing after completion are self-preservation rules that every Shuangbei homeowner must know.

Two core causes of bathroom leaks in Shuangbei old houses

To solve the leak, you must first understand where the water leaks from. Bathroom water leakage is mainly divided into two types: "pipe leakage" and "waterproof layer failure":
1. Pipe leakage: This is usually a rupture of the hot and cold water pipes in the wall or the drainage pipes under the floor (such as toilet waste pipes and floor drain pipes). If the hot water pipe is leaking (old houses often use iron pipes, which are prone to rust), it is usually a "continuous drip", and the leak will occur even if there is no water upstairs. This requires professional plumbers to perform pressure testing, positioning and partial pipe replacement.
2. Waterproof layer failure: This is the most common situation. The cement wall itself actually has tiny pores. The purpose of the waterproofing project is to apply a layer of impermeable "waterproof membrane" (such as elastic cement or PU) on the cement surface. If the waterproof layer is aged, cracked due to earthquakes, or the coating thickness is insufficient during construction, water will penetrate into the cement layer during bathing and leak downstairs. This kind of leakage is usually "intermittent", that is, after taking a shower upstairs, the water will start dripping downstairs.

Standard bathroom waterproofing project: these five key steps cannot be omitted

A bathroom waterproofing project that can last for more than 10 years must strictly abide by the following standard steps during construction. Homeowners should pay special attention when supervising the construction:
Step 1: Thorough cleaning of the base (prime tidying). Waterproof paint cannot be painted directly on walls with dust, oil stains or loose cement. The master must thoroughly remove the old tiles and cement mortar layer (down to the red brick or RC structural wall), and clean the surface dust, otherwise the waterproof layer will not be able to adhere tightly to the wall.
Step 2: Make mud base and drainage slope. After removal, the plaster master will paint with cement mortar to level the walls and floor, and create a "drainage slope" to flow to the drainage holes to avoid water accumulation on the ground in the future.
Step 3: Reinforce the corners and around the pipe (the most vulnerable points for water leakage). The joints between the wall and the ground (inside corners) and around drainage pipes are the places where a house is most likely to crack due to earthquakes. Professional construction methods will paste "non-woven fabric" or "glass fiber mesh" in these corners for crack-resistant reinforcement, and then apply waterproof paint.
Step 4: Apply at least two to three layers of elastic cement. Waterproof coating (usually using elastic cement) should not be applied too thickly at one time, otherwise it will easily dry out and crack. The principle of "thin coating and multiple coats" must be adopted, brushing once horizontally, and then brushing vertically a second time after it is completely dry to ensure that there are no pores. It is recommended that the waterproof height of the wall should be at least 180 centimeters (it is recommended that the shower area be at the top), and the non-shower area should also be 120 centimeters.
Step five: closed water test (water storage test). This is the only criterion for testing waterproofing effect. After the waterproof layer dries, the drainage holes must be sealed, fill the bathroom floor with water to a height of about 3 to 5 centimeters, and let it sit for 24 to 48 hours. During this period, you need to observe whether the water level has dropped, and go to the residents' homes downstairs to observe whether there are leaks in the ceiling. Only after confirmation can you start laying tiles.

A reasonable budget for bathroom renovation and waterproofing projects in the Taipei area

In the greater Taipei area, bathroom project expenses include multiple types of work (demolition, water and electricity, mud work, waterproofing, tiling, and bathroom equipment installation), and the waste removal and transportation costs are extremely high. The overall budget is as follows:
1. Simple bathroom waterproofing layer construction (excluding dismantling and restoration): If you only apply waterproof paint to the rough wall, the labor and material cost is approximately Between NT$ 15,000 and NT$ 25,000 (depending on the number of bathroom square meters and the height of the waterproof layer).
2. Complete bathroom renovation project (dismantling + water and electricity restoration + waterproofing + tile restoration): For a bathroom of about 1.5 square meters to 2 square meters, the standard project quotation in Taipei usually falls between NT$ 150,000 to NT$ 250,000. The approximate cost distribution is: demolition and garbage removal (approximately NT$20,000-35,000), water and electricity pipelines and bathroom piping (approximately NT$35,000-50,000), mud base and drainage slope (approximately NT$40,000-60,000), waterproofing project (approximately NT$15,000-25,000), tile paving and materials (approximately NT$40,000-70,000). Bathroom equipment (toilet, shower head, wash basin, exhaust fan) depends on the brand.

Three major reminders for house owners to prevent pit supervision

1. : Some unscrupulous work teams are rushing to finish work. They directly apply waterproofing before the cement mortar is dry, or use low-quality moisture-proof paint. The industry is required to specify the brand of waterproof coating (such as Golden Monkey, Nanxing and other major manufacturers) in the contract.
2.: Water testing is the most important milestone in waterproofing projects. Please be sure to go to the site to check the water level in person after draining the water and before laying the tiles, and even say hello to the neighbors downstairs to confirm the condition of the ceiling downstairs together, and take photos to keep as a basis for clarifying responsibilities in the future.
3.: Formal waterproofing projects should provide at least 2 to 5 years of water leakage warranty. The scope of the warranty must be clearly specified when signing the contract (for example, whether it includes restoration of damaged tiles), and do not just agree verbally.