[Taipei Moist Wall Cancer Prevention and Control] The wall is peeling off powder and bubbling, and you can’t finish blowing it? Get rid of the omnipotent myth of "high-pressure grouting injection"! High wall pressure chemical wall cancer treatment and alkali-resistant microcrystalline waterproofing method

The wall cancer curse in Taipei Basin: Why does the paint blister again?

The topography of Taipei City and New Taipei City is a basin. Coupled with the several-month-long rainy season and winter northeast monsoon every year, the average relative humidity is as high as 75% to 85%. In many medieval houses or old apartments in Shuangbei, "Wall Efflorescence" on the walls is a chronic disease that gives countless homeowners a headache. Many people saw mold on the walls, powder peeling off, and cement bubbling and peeling off, so they bought soil and anti-mold paint to cover them. As a result, the wall cancer broke out again within three months. Some people also spent a lot of money to find a manufacturer to perform "high-pressure grouting (commonly known as injection) on the wall," thinking that they could get rid of it once and for all. Unexpectedly, water vapor squeezed out of the cracks near the injection site soon after, and the scope of wall cancer expanded. To completely solve wall cancer, we must first clarify the chemical mechanism of its occurrence and get rid of blind myths about injection methods.

The chemical nature of wall cancer and the technical myth of "high-pressure grouting injection"

Wall cancer is called "efflorescence" in architectural engineering. When there are micro cracks inside the cement wall and moisture continues to penetrate, the moisture will dissolve the calcium hydroxide Ca(OH)₂ in the cement. When these aqueous solutions containing calcium ions penetrate into the wall surface and come into contact with carbon dioxide CO₂ in the air, they react to form water-insoluble calcium carbonate CaCO₃ crystals. During the expansion process, these crystals will push away the paint coating on the wall, causing it to bubble, powder and fall off.

[Dispelling the injection myth] The principle of high-pressure PU foaming agent grouting (injection) recommended by many leak-catching manufacturers is to use a high-pressure pump to inject foamed polyurethane into cracks in the wall, and when exposed to water, it expands and blocks the waterway. However, the injection method is only suitable for "emergency water stop of structural cracks in continuous structures" and is not suitable for treating extensive water vapor penetrating wall cancer. The PU foaming agent injected into the wall will gradually become brittle and fail after a few years; more seriously, the injection will only block the waterway at best. After the water vapor is accumulated under high pressure in the wall, it will find the nearby more fragile cement pores to break through, causing wall cancer to break out in a large area on the adjacent wall (commonly known as the transfer effect).

Scientific steps to cure wall cancer: finding water sources and negative water pressure silicic acid construction method

To cure wall cancer, water, electricity and waterproofing engineers emphasize the need to implement the trilogy of "water treatment, bone scraping, and crystallization waterproofing":

1. The first step: Accurately check the water source (water control): Wall cancer must have a water source! It is necessary to first use an "infrared thermal imaging camera" and a high-precision wall moisture content tester to determine whether the water source comes from small leaks in the hidden water supply and drainage pipes in the wall, failure of the waterproof layer of the exterior wall, secondary pouring cracks in the window frame, or water accumulation in the attic bathroom. If the leakage in the pipeline is not repaired, no matter how much surface waterproofing is done, it will be in vain.
2. Step 2: Thoroughly remove the damaged cement layer (bone scraping): Use a stone grinder to deeply scrape off the paint in the area where wall cancer occurs and the cement mortar layer damaged by carbonation until the hard red brick layer or original concrete structure is exposed, and wash away the surface dust with clean water.
3. Step 3: Apply water-based silicic acid penetrating crystal waterproof coating:Apply a waterproofing material with active silicate ingredients (such as deep silicate waterproofing material). Silicic acid can penetrate deep into the wall along the pores of the cement. When it encounters free calcium and moisture, it will react to form water-insoluble needle-shaped crystals, filling all micro pores to achieve the effect of blocking water vapor. This "negative water pressure (water surface on the back of the body) waterproofing" can effectively resist moisture inside the wall.
4. Step 4: Restoration of alkali-resistant primer and cement mortar: Mix the cement mortar with alkali-resistant strengthener for leveling, and finally apply highly breathable alkali-resistant and mildew-resistant latex paint to complete the standard repair.

CapEx Budget Planning for Shuangbei Medieval House Wall Cancer Repair

For owners of historic houses or investors in commercial real estate flips, when evaluating the cost of wall cancer repairs, they should distinguish between minor and severe levels:

Conclusion: Use scientific waterproofing to completely remove wall cancer labels

Mural cancer is by no means an incurable terminal disease. The key is to give up reliance on shortcut myths such as high-pressure injections. By using infrared thermal imaging cameras to trace the source of water leakage, and using scientific engineering methods such as silicic acid infiltration crystallization that can symbiosis with the cement structure, the chemical reaction of water vapor crystallization can be blocked for a long time. Whether it is to create comfortable and non-toxic air quality for self-occupation, or to renovate old-fashioned house assets in Greater Taipei, completely eradicating wall cancer is the most solid line of defense to ensure the structural safety of the house and create space for property premiums.