Don’t rush to repair after the typhoon! Correct repair times and common mistakes for wall cancer, mold and silicone caulking

Rushing to build a wall just after the typhoon? Wait first

After the typhoon, many homeowners in Taipei and New Taipei opened their windows and saw that the wall near the window was wet, the paint was bubbling and peeling, and white powder or black mold began to appear in the corners. The first reaction is usually to find a master to repair it quickly and cover up those ugly marks.

But experienced waterproofing masters will all tell you the same thing: "Don't worry, let the wall dry first."

Why? Because the rainwater brought by the typhoon is not just on the surface of the exterior wall. Strong winds can force rainwater into micro-cracks in exterior walls, seams in window frames, and gaps in tiles. This moisture will penetrate into the concrete and red bricks of the wall, and it will take several days or even a week or two to evaporate and dry naturally.

If you rush to scrape off the wall cancer, paint it with new paint, or apply silicone when there is still a lot of moisture inside the wall, you will be "sealing" the moisture inside the wall and unable to get out. The trapped moisture will continue to corrode the wall, causing the newly painted paint to bulge and peel again after a few months, making the wall cancer more serious than before. This is also the reason why many people think that "wall cancer can never be cured" - it's not that it can't be cured, but that the timing is not right.

Correct steps after a typhoon

The first stage: emergency leak stop (on the day of the typhoon or the next day)

If the window frame is leaking, take temporary measures to stop the leakage:

• Stuff the bottom of the window frame with absorbent towels or old clothes to absorb water
• Cover the floor with a tarpaulin or a large plastic bag, and use a bucket to carry it over
• Check whether the window frame drainage hole (usually a small hole in the track below the window frame) is blocked by sand or mud

Phase 2: Wait for drying (3 to 7 days)

After the weather stabilizes, let the damp walls dry naturally. You can use a dehumidifier or electric fan to speed up the process, but do not use a heat gun to blow directly on the wall. The high temperature may cause the surface to dry too quickly, and the moisture inside will be locked. Under Taipei's summer ambient temperature and humidity conditions, a wall of average thickness will take approximately 3 to 7 days to dry.

The third stage: Diagnosing the water source (after drying)

Before starting any repairs, the most critical step is to find out where the water is coming from. Where you see a leak is not necessarily where the water is getting in - the water could seep in through a crack several meters away and follow a path inside the wall to where you see it.

Common water entry points include:

1. Deterioration of window frame silicone:This is the most common cause. Silicone will begin to crack, peel, and lose its sealing effect in about 5 to 8 years.
2. Cracks in exterior wall tiles: Smear cracks in the tiles themselves or in the grout can allow rainwater to seep in.
3. Ageing of the waterproof layer on the attic: If you live on the attic, water seepage from the ceiling is usually a sign that the life of the waterproof layer has expired.

The fourth stage: professional repair (after confirming it is dry and finding the water source)

The standard radical treatment process for wall cancer is as follows:

1. Completely scrape off the moldy and peeling old paint and loose cement layer
2. Apply mold remover to kill mold spores
3. Repair external sources of water ingress (re-silicon, repair cracks in tiles, or waterproof exterior walls)
4. Confirm that the internal moisture content drops below the safe value (professional masters will use a moisture meter to measure)
5. Apply one or two coats of alkali-resistant sealing primer (to prevent cement alkaline substances from re-precipitating to form wall cancer)
6. Final topcoat completed

The correct approach to silicone re-printing

Many people think that silicone can be squeezed out and wiped on, but in fact its construction quality directly determines how long the leak-proof effect will last:

• Old silicone must be completely removed: New silicone cannot stick to old silicone. Use a silicone scraper and solvent to completely remove the old glue.
• Keep surface dry: Silicone's adhesion is greatly reduced on wet surfaces.
• Choose neutral silicone: Acidic silicone is cheap but can corrode metal door and window frames. Be sure to use neutral silicone for caulking of window frames.
• Prepare the seam after punching: After squeezing it out, use your fingers or spatula soaked in soapy water to press the silicone into the seam to ensure that it is tightly attached to the materials on both sides.

Long-term maintenance: perform a patrol every year before the typhoon season

Taiwan’s humid climate and frequent earthquakes will cause the waterproofing of exterior walls and window frames to continue to deteriorate. It is recommended to spend half an hour doing a patrol every year before the typhoon season (around May or June):

Conclusion: To treat wall cancer, we must cure the root cause and choose the right time

Wall cancer is not a terminal disease, but it requires the correct sequence of "cutting off the water source first, then waiting for dryness, and finally treating the surface." Impulsive repairs after a typhoon often only temporarily cover up the problem, only to reappear a few months later. Only by patiently waiting for the wall to dry out, finding the real water ingress point, and repairing it step by step can we truly say goodbye to wall cancer.