Answer:
(1) Although this method of construction has the advantages of being fast and low-polluting, it also has the following blind spots in terms of actual performance:
(1) The contractor must possess proficient skills and knowledge to accurately calculate the volume of materials to be injected and the expansion rate, otherwise it may lead to subsequent problems such as deformation of the window frame or poor waterproofing.
(2) The success rate is extremely low if the original mortar joints have wood chips left inside or if red bricks are used in the construction; these conditions are actually very difficult to observe with the naked eye.
(3) Excessive inflation can also easily lead to safety and health incidents such as tiles bulging and falling off.
(2) Based on my years of experience, this construction method, although quick and inexpensive, is actually not very effective; it is more of a superficial approach to meet the needs of the residents. This is because:
(1) If the problem of the embedded seam flaw is severe, this type of construction method is like “scratching at a scab,” with no effect whatsoever.
(2) Most transparent non-film water repellents are applied directly to the tile surface; their ability to resist ultraviolet rays and ozone is very low, and their waterproof function will gradually disappear after about six months to a year.
(3) There is also no waterproof effect for the fine cracks in the RC and the paint layer.
(4) Although water-repelling agents are advertised as having high permeability and that tiles will not change color, most water-repelling agents will cause the color of the tiles to gradually deepen and darken after three months. The surface of tiles in darker color series may be less affected, but the surface of some lighter color series will still affect the appearance.
In short, the coating method of water repellents can only reduce the infiltration of rainwater to a certain extent, and cannot achieve a permanent leakproof function. Therefore, the author recommends that for long-term maintenance, in addition to applying water repellent coatings on the exterior, a combination of renovation techniques or injection techniques is necessary for long-term success.