In terms of roofing construction, the waterproofing layer placed above the insulation layer is known as the "right-lying method," while the one placed below the insulation layer is called the "inverted-laying method." The waterproofing layer being placed above the insulation layer is done for the purpose of protecting and...Wen MaterialsMoisture absorption issues can arise, as once the waterproofing layer is damaged, the thermal insulation material absorbs moisture, leading to leaks; if the waterproofing layer is placed beneath the insulation, the material's moisture absorption will negate its insulating effect.
Inverting the laying method compared to the traditional upright laying, it eliminates thermal expansion and contraction of the waterproofing layer, thereby extending its lifespan. Moreover, the insulation layer offers a physical protection to the waterproofing layer, safeguarding it against external damage. However, this method imposes stricter requirements on the insulation material.
Roof waterproofing is an indispensable and crucial process for ensuring building quality. Many stages and fine details are often overlooked, and poor handling can easily lead to issues. In reality, controlling the quality of roof waterproofing is not a difficult task; the key lies in properly addressing three layers: the thermal insulation layer, the slope and level finding layer, and the waterproofing layer.
Waterproofing Layer: Ensure the base surface remains dry, flat, and firm. The corners should be rounded off. A simple method to check dryness is to lay a 1 square meter roll flat on the leveling layer, let it sit for 3-4 hours, then uncover and inspect. No watermarks on the leveling layer or the roll indicate it's ready to apply the base treatment agent and proceed with laying.
Apply the tiles starting from the downhill slope of the water flow, proceeding in the order of farthest to nearest, ensuring the length of the rolls is perpendicular to the water flow slope and overlap in the direction of the water flow. The upper and lower layers of tiles must not be laid perpendicular to each other; the laid tiles must be offset by 1/2 the width.
When using polymer-modified asphalt waterproof membranes or synthetic polymer waterproof membranes, the overlap should be 80mm for full-adhesive methods, 100mm for dry-laid, spot-adhesive, and strip-adhesive methods. For synthetic polymer waterproof membranes using welding methods, the overlap should be 50mm.

Leveling Layer: The leveling layer should have partition grooves, typically with a width of 20mm; the spacing between longitudinal and transverse partition grooves in cement mortar or fine stone concrete leveling layers should not exceed 6 meters. The partition grooves should be filled with asphalt sand or elastic sealing material; the base layer should have the correct slope and be smooth and clean, with a deviation in flatness not exceeding 5mm and no hollowing or cracks; the partition grooves of the waterproof leveling layer, waterproof protective layer, and surface layer should correspond vertically and horizontally, and the reserved position for the surface layer partition grooves should meet the requirements of the acceptance specifications.
Insulation and Heat Retention Layer: The pipe roots passing through the roof and wall surfaces should be securely fastened. Use fine stone concrete mixed with 3% expansive agent to fill and compactly seal the pipe root area, ensuring a secure fixation.
Steam exhaust channels are typically spaced less than 6 meters apart, with the enclosed area being less than 36 square meters. The steam exhaust channels should be disconnected from the insulation layer to the waterproofing layer. No mortar, cement, sand, or other powdery materials should be mixed into the steam exhaust channels to ensure unobstructed steam release to the exhaust pipe. The steam exhaust outlet should be buried with the exhaust pipe, which should be placed above the structural layer; the pipe walls passing through the insulation layer should have steam exhaust holes. The steam exhaust holes on the roof should be consistent in method, neatly arranged, and aesthetically pleasing, ideally located at the intersection of longitudinal and transverse separation joints.