Answer:
(1) Most waterproof materials are not afraid of water; they are afraid of the sun (the ultraviolet rays and ozone in the sun have a great destructive effect on waterproof materials). Therefore, adding an additional layer of insulation to the waterproof material not only reduces the indoor temperature but also can increase the lifespan of the waterproof material, which is beyond doubt.
(2) The most commonly used thermal insulation materials currently on the market can be divided into the following categories:
(1) Heat-insulating paint made from inorganic mica mixed with organic resin, but such materials gradually lose their heat-insulating effect after about two to three years, so the number of cases using this type of material has been decreasing year by year over the past 30 years.
(2) In conjunction with the PU elastic waterproof material, a similarly elastic white thermal insulation cream is added (must be white). Its main function is to achieve thermal insulation through the constant temperature and non-absorbent properties of mica powder and sunlight refraction—such materials can only be used on exposed roofs; if used on a covered roof, they do not have this function.
(3) In general, the roofs in Taiwan are mostly covered roofs, so most of the thermal insulation materials, apart from the cheapest foam concrete, are usually porous sheet-shaped insulation materials that use the effect of air insulation, such as PU foam, eco-friendly PE, PS board, carbonated calcium lightweight rock panel, etc.
(4) The best thermal insulation effect mentioned above should belong to PU foam, but most of these are used in refrigerators and storage rooms. It has been applied to the roof in some cases; its thermal insulation effect is excellent, but it also causes many side effects (when the roof gets flooded, the PU foam material floats up; even with a covering layer on top, this is not an exception).