Answer:
(1) The author believes that the problem of waterproofed window and door joints is a very important aspect of the construction process (Have you noticed how many construction sites are littered with watermarks and paint peeling off the walls near the windows every time there is a typhoon or heavy rain? I’m sorry to say that the vast majority of builders do not take this consequence seriously and resort to low-cost contracting (only 30 to 40 yuan per meter). Imagine if the cost of installing these joints were as high as 3,000 yuan per meter. How many windows would a worker have to install per day? This includes material handling, waterproofing materials, and subsequent cleaning. How can “fast workers” handle “difficult tasks”? The vast majority of window installers have seriously neglected the essential requirement of waterproofed mortar due to the demands of “speeding up work” and “meeting quotas.”
(ii) Key points of the window frame waterproof appeal:
(1) Surface preparation – Before construction begins, impurities such as mud, corks, and cement bags near the window frames must be removed.
(2) To increase the adhesive properties of cement mortar, the structure at the window should be moistened first.
(3) Accurate cement-sand ratio—preferably 1:2.5; do not ever increase the cement-sand ratio to 1:4 or 1:5 for convenience in operation.
(4) Proper water-lime ratio—Excessive water-lime ratio leads to excessive porosity in the cement mortar, and the coarser the pore size, the higher the water absorption rate; too low a water-lime ratio results in incomplete hydration, which affects the strength of the cement mortar and also increases the water absorption rate.
(5) When mixing cement sand, it is necessary to add a high molecular weight waterproofing agent and a small amount of methyl cellulose (seaweed powder).
(6) After the grout is complete, it is best to apply two or more coats of 20 to 30 cm thick water-based and cured waterproofing material (and it must be applied before the primer is applied; please be careful not to apply it after the primer has been applied!).
(7) The grout used after the tiles are finished must have good adhesion, elongation, and weather resistance; it is best to use modified single-fluid PU, polyurethane, or alkaline SILICONE grout materials to avoid subsequent problems such as peeling or cracking.