Answer: Not advisable.
(i) Generally speaking, the majority of water leakage in the courtyard occurs at the connection points such as floor cracks, corner construction seams, corners, ventilation ducts, manholes, and around the water outlets (as listed in question 50). The elastic waterproof adhesive or elastic cement have much lower elasticity, tensile strength, and weather resistance than water-based materials. Moreover, the waterproof layer in the courtyard must withstand the weight of the soil, RC concrete, and the foundation; if the thickness is insufficient, it may not be able to maintain long-term waterproof performance. And if the waterproof material is to be applied over 3mm, it must be applied in more than five coats, which will inevitably prolong the construction period. Therefore, based on the principle of choosing the lesser of two evils, I believe that it is really not necessary to make this change. If the problem of water leakage still occurs after the handover, the renovation costs alone will be several times higher.
(ii) General contractors generally understand the serious consequences of switching to water-resistant materials, but under the combined consideration of rush to complete the work—the urgency of subsequent projects and obtaining usage permits—and the erroneous guidance of inexperienced material suppliers, they often change the construction method and materials in a blink of an eye, causing numerous subsequent problems. However, this situation continues to occur in Taiwan, creating a thriving business opportunity for repair and leakage engineering companies. From a civilized country’s perspective, this is a very ironic phenomenon.