Water leakage and seepage are often found in the exterior walls of buildings, which not only affect the structure and durability but also severely impact the aesthetics and functionality. The causes of water leakage on the exterior walls are numerous, mainly categorized into: water leakage through the exterior brick masonry; seepage around the door and window frames on the exterior walls; and water leakage caused by external water sources.

One, exterior brick masonry leakage

During our site visits, we often find leaks on the exterior walls, with the western side walls typically having more issues than the eastern ones. In frame structures, leaks are often found at the bottom of the frame beams. Leaks in the exterior walls can lead to mold formation on interior wall decorations, affecting both aesthetics and functionality.

(1) Reason Analysis

1. Poor bricklaying skills, insufficiently filled mortar in brick joints, or hollow joints. Leaks occur due to gaps between the perimeter walls of frame structures and the bottom of the frame beams, caused by settlement of the masonry.

2. Scaffold eyes were not properly sealed, leaving channels for water leakage.

3. When the exterior decorative layer has hollowed areas or cracks, after rainfall, water enters the plaster layer through the gaps and seeps into the interior wall.

(II) Method of Handling

When the exterior wall of a high-rise building has localized water leakage, scrape off the interior plaster, identify the brick joints causing the leakage, remove the loose mortar from the non-tight parts, clean it thoroughly, and then fill it densely with 1:2.5 cement mortar.

When there is extensive seepage but no obvious cracks on the exterior decorative surface, clean the wall with a brush and rinse it thoroughly. After it dries, mix the A and B components of the cationic chloroprene polymer emulsion in a 1:1 ratio, stir them well. Then, add ordinary Portland cement with a grade of 42.5 according to a water-cement ratio of 0.4, and mix the cement slurry thoroughly. Use the polymer cement slurry to grout the brick joints.

When leakage occurs at the bottom of the frame beam, the decorative layer at the crack of the outer wall should be scraped off, the mortar in the gap of the brick wall top surface should be scraped out, cleaned thoroughly, and tightly sealed with iron strips. Then, fill it tightly with 1:2.5 cement mortar, recessed 10mm into the wall surface, and seal it with flexible waterproof sealant. Finally, re-decorate the outer wall surface layer.

(3) Control and Prevention Measures

1. Enhance construction management, strictly enforce the operation quality of masonry, and adhere to the provisions of the "Code for Construction and Acceptance of Masonry Works." No openings are allowed in the exterior walls. The joints of brick masonry should be level and vertical, with even thickness and a mortar filling rate exceeding 80%.

2. For the framed structure's partition walls, as per the standard requirements: "When the partition walls are nearly up to the bottom of beams and slabs, a certain gap should be left. Before plastering, side bricks, upright bricks, or blocks should be diagonally packed using side bricks, upright bricks, or blocks, with an inclination of approximately 60°. The masonry mortar should be well-packed." This is the primary measure to prevent the settlement of masonry mortar in partition walls.

3. Prior technical briefing is mandatory before exterior wall construction. Ensure the use of grouting technique during the laying process, and conduct a thorough check for hollowed areas before jointing. Ensure the joints are dense, and pay attention to moistening and maintenance after jointing. Do not miss any dense joints, and strictly control the depth of the joints; the indentation should not be too large, and it's best to form a circular arc flat joint. Establish a multi-level review and control system for quality management to ensure the quality of each process.

Issue: Water leakage around exterior windows and door frames

During construction, we often find water leakage around the window and door frames, as well as on window sills. Such leaks can lead to soiling of indoor walls and affect their functionality.

(One) Reason Analysis

1. The gaps around the window and door frames where they meet the brick walls are not sealed, or although they are filled with mortar, they are not dense, often leading to peeling and cracking. There is no drip line at the top of the window opening, allowing rainwater to enter the room through the top of the opening.

2. The masonry gaps beneath the windowsills are not properly filled with mortar, allowing water to seep into the room through the gaps. Additionally, improper painting of the windowsill has led to water渗ing indoors along the bottom of the window frame.

(II) Method of Handling

1. Remove and clean the loose material and cracks, as well as the non-tight mortar from the gaps between the window and door frames and the wall. Then, fill the gaps with 1:2.5 cement mortar in layers, leaving a 6mm x 6mm groove along the edge of the window frame. After the exterior decoration is completed, fill the grooves around the window and door frames with flexible waterproof sealant.

2. The top of the door and window openings must have a drip line, and any damage must be repaired properly. If there are cracks or water leakage in the painted layer of the window sill, the work must be redone.

(3) Control Measures

1. After the window and door frames have been inspected and approved, the gaps are sealed. The surrounding walls and frame sides are cleaned, then moistened with water spray. Mixed mortar is layered and compacted, followed by smoothing out.

2. Brickwork beneath the window sill must be filled with mortar to seal all the gaps, with a minimum distance of 45mm between the sill brick surface and the window frame. The upper edge of the sill's water flow slope should be recessed into the window frame below, forming a 20mm-radius curve; the lower edge should have a 10mm x 10mm drip groove.

Section Three: Water leakage from the exterior wall caused by external water sources.

Water leakage occurs when the parapet wall allows water to seep into the interior, or when the canopy's runoff infiltrates the wall, or when balcony runoff penetrates the wall, or when the downspout is damaged. This external water contaminates the wall, seeps into the interior walls, causing dampness and mold, thus affecting the aesthetics.

Reason Analysis

1. The parapet roof is inverted and water flows outward; there is no drip line or槽 at the outlet; rainwater runs down the gable wall.

2. The canopy's drainage pipe diameter is too small or clogged, causing overflow; or the drip line槽 was not properly installed, allowing rainwater to flow to the base,渗入the interior wall or run along the exterior wall.

3. The downspout material is poor, aging quickly, prone to damage, and often comes apart, causing large areas of the exterior wall to become damp with rainwater. Alternatively, if the downspout is installed improperly, close to the wall, it may overflow, with water, drainage, and leaks all flowing down the wall.

(II) Treatment and Prevention

1. Prevent the女儿墙 from pressing against the eave edge. The outer surface of the cap should be higher than the inner side, forming an inward-sloping flashing to allow rainwater to drain onto the roof. On both sides of the cap at the bottom, proper drip lines must be installed.

2. Prevent water dripping from awnings. When using a baffle on the outside, implement organized drainage by increasing the diameter of the drainage pipe to no less than 50mm, extending it outside the awning's opening by at least 70mm, and ensuring a slight slope. Additionally, the outer edge should be cut at an angle, and a drip line should be installed at the bottom of the panel to prevent water runoff.

3. Wall drainage pipes installed. During our follow-up visits, we found that many wall leaks are due to the small diameter, poor quality material, and improper installation of the drainage pipes, which lead to overflow and leakage, affecting large areas of the wall. Therefore, it is crucial to strictly control the quality of the drainage pipes and strictly adhere to the provisions in the "Technical Specification for Roofing Engineering": the inner diameter of the drainage pipes should not be less than 75mm, and the maximum roof drainage area for general drainage pipes should not exceed 200m². The installation distance of the drainage pipes from the wall should not be more than...