Waterproofing construction process for vertical joint metal roof

Roof waterproofing is an extremely important aspect. Standing seam metal roof panels themselves have excellent waterproofing properties, but some metal roofs still experience leaks during use. There are many factors that cause leaks in metal roofs. During installation, different workers' techniques and the building structure can lead to varying installation results. So, what are the main causes of roof panel leaks, and what are the corresponding solutions? Generally, the main factors to consider regarding the self-waterproofing performance of a roofing system include the connection method of the aluminum-magnesium-manganese roof panels and the edge finishing methods of the supporting systems. Roof leaks are mainly prominent at: the ridge, the connection points of the metal roof skylights, roof openings, the connection between the gable wall and the roof, and the interior gutters.

I. Causes of Leaks
1. Large roof curvature, roof panels not perpendicular to the building columns. The joints of standing seam metal roof panels are weak points, and these joints affect both the waterproofing quality and the strength of the roof panels. 1. Unprofessional construction techniques can easily lead to leaks.

2. Excessive segmentation and lack of slope in the gutter installation of standing seam metal roof panels. Insufficient slope causes water accumulation during rain or snow, corroding the roof and causing leaks.

3. Excessive spacing between the alloy supports of standing seam metal roof panels leads to uneven stress on the roof, causing deformation and leaks.

4. Inexperienced operators of edge-trimming machines during installation of standing seam metal roof panels can result in improper edge trimming and leaks.

5. For connection points such as gable walls, some construction workers simply connect the flashing to the outermost rib of the roof panel with self-tapping screws. These screw holes inevitably penetrate the roof, causing leaks if the seal fails.

6. Excessive deformation during welding of water pipes to the gutter can cause localized bulges and water accumulation.

7. Improperly secured roof panels and an inadequate drainage system design.

II. Countermeasures Waterproofing standing seam metal roofs is a crucial measure. Besides paying attention to installation techniques, thorough preparation before installation is essential.

1. Carefully inspect the metal roof before construction to ensure it is secure, clean, and free of debris.

2. Identify areas requiring waterproofing: Areas requiring waterproofing for standing seam metal roof panels generally include horizontal overlaps, vertical overlaps, fan vents, pipes extending from the roof, air conditioning ducts, the perimeter of skylights, gutters, ridges, junctions between metal panels and parapet walls, and screw fasteners – weak points in the waterproofing of the metal roof.

3. Select T-shaped clamps compatible with the roof panel specifications. Place the T-shaped clamps in the appropriate positions to prevent damage to the standing seam metal roof panels during clamping.

4. Check the straightness and flatness of the T-shaped clamps to ensure they are on a horizontal line.

5. Preheat the surrounding area before welding gutters to reduce welding deformation and protrusions. Control the error within 2mm. Strengthen post-weld inspection and grinding.

6. Adjust the slope to ensure smooth drainage.

7. Avoid stepping on or deforming aluminum-magnesium-manganese roof panels during installation.

Note the installation method at some key points: For the gable wall, first, fix the prefabricated aluminum alloy gable wall fastener to the roof panel ribs with rivets. Then, use gable wall fasteners to secure the fastener to the mounting base, thus firmly fixing the fastener. Next, attach the prefabricated T-shaped adjustable fastener to the fastener. Finally, fix the gable flashing to the T-shaped adjustable fastener with rivets. Since the exposed rivet holes do not penetrate the roof panel, there will be no gaps.

The gable wall construction involves first fixing the prefabricated aluminum alloy gable wall groove to the roof panel ribs with rivets, then securing the groove to the fixing base using gable wall fasteners. This firmly secures the groove. Next, a prefabricated T-shaped adjustable groove is inserted into the gable wall groove. Finally, the gable flashing is fixed to the T-shaped adjustable groove with rivets. Since the exposed rivet holes do not penetrate the roof panel, there will be no leaks.

Leakage at the ridge is mainly due to rainwater backflow. Inadequate sealing under the ridge cap can easily cause leaks. Insufficient connection strength of the ridge cap, leading to connection failure under thermal expansion and contraction, is another cause of leakage.

① Install metal plugs matching the roof panel type under the ridge cap;
② The connection between the flashing at the intersection of the ridge tiles and the aluminum-magnesium-manganese roof panel should use an overlapping connection, with an overlap length not less than 200mm.

③ The overlap between the ridge tile and the aluminum-magnesium-manganese panel should not exceed 50mm, as a large distance will affect the windproof effect.

During construction, ensure the gutter slope is corrected immediately during the construction process to reduce accumulated deviations and ensure smooth drainage. When welding the gutter, preheat the surrounding area to reduce welding deformation and protrusions, keeping deviations within 2mm. Improve the inspection and polishing work after welding.

When installing metal roofing, it should be done under the guidance of professionals. Leaks in aluminum-magnesium-manganese metal roofs can be very troublesome, so waterproofing is a crucial step in the construction of vertical joint metal roofs. The construction method is very important; a professional construction team should be selected.