1, causes analysis of external wall leakage
There are many reasons for the leakage of the external wall of residential projects, such as design mistakes, improper material selection, irregular construction technology, careless details, improper decoration after delivery, and the influence of natural environmental conditions. Specifically, there are the following aspects:
1) Design and maintenance of external wall downpipe;
2) The reserved hole in the external wall is poorly sealed;
3) The production and installation of aluminum alloy or plastic steel windows are not standardized;
4) The external wall brick base is not thoroughly cleaned, the paste mortar is not full, and there is water or accumulated water between the wall and the brick;
5) Exterior wall plastering cracks;
6) uneven settlement of foundation leads to wall cracking;
7) In the second decoration stage of the house, the wall cracks due to structural changes caused by disorderly construction;
8) Temperature cracks on the external wall of the top surface of the building.
2. Prevention and treatment of external wall leakage
2. 1 Prevention and treatment of external wall leakage caused by storm sewer
1) In the design of building structure, it is suggested that downpipes should not be located in columns or walls in general residential projects. If necessary, galvanized steel pipes should be used for burying, especially the joints should be tight, and irrigation tests should be carried out.
2) During use, the external wall downspout should be kept intact and unblocked, and the damage should be repaired in time to avoid leakage caused by long-term running water on the external wall.
2.2 Prevention and treatment of poor sealing leakage of reserved holes in external walls
1) By improving the construction technology, the lien on the operating hole of the external wall is reduced as much as possible.
2) After the sundries in the operation hole are cleaned and watered and wetted, carefully fill the outer wall hole with cement mortar and bricks to ensure compactness.
3) Strictly implement the inspection system. When inspecting the main structure of the project, resolutely rework the irregular and loose holes filled in the external wall.
2.3 prevention and treatment of window sill and aluminum alloy or plastic steel window installation is not standardized leakage.
1) windowsill. Engineering leakage is caused by improper setting of windowsill. In view of the reasons such as the small slope of the window sill and the aging and falling off of the filled silica gel, measures are taken: apply silica gel along the straight line of the small arc of the window sill, and part of the glue will be squeezed through the reserved gap between the lower frame of the window and the small ring to ensure the elastic connection between the window and the wall of the hole.
2) window frame.
A. turn off the good stuff. In particular, the thickness of aluminum profile and oxide film should be controlled.
B. stop production. The error of blanking size should be strictly controlled within the allowable deviation range, so that the formed window frame can achieve tight joint and overall founder. Make the lower frame water outlet.
C. close the construction. Strictly control the reserved size of the hole in the window, glue the inside and outside in place, and be dense and straight.
D. inspection and acceptance. When the window project is accepted, the water spray test is used to check its impermeability and the smooth running water and water accumulation in the lower frame of the window.
2.4 Prevention and treatment of leakage of external wall tiles
1) The exterior wall tiles that enter the site shall be sampled and retested in strict accordance with the specifications, and the tiles that fail the retest shall not be used in the project. Select the tiles one by one, and reject the tiles with appearance defects (such as cracks and missing corners).
2) Construction shall be carried out in strict accordance with the procedures for tile laying. When the block area is small, the method of one bottom and one middle edge can be adopted, that is, one bottom is scraped, one middle is plastered with gray, and the other side is plastered with bricks; When the block area is large, the method of one bottom and two sides can be adopted.
3) Grassroots cleaning. Clean up the wall, so that the mortar joint of masonry is recessed into the wall 10mm, and the short joint is repaired with 1: 3 cement mortar to increase the bonding force with the base mortar.
4) Before the construction of1d, water the wall evenly, remove dust and use the wall to absorb a certain amount of water, then apply 5 mm ~ 7 mm thick 1: 3 cement mortar and compact it with an iron trowel.
5) Wipe the middle ash. First, put 1: 3 cement mortar mixed with 5% waterproof powder on the rough ground, with a thickness of 5 mm ~ 7 mm, and use a wooden wedge for grouting and leveling, and use a trowel for leveling.
6) Check the wall surface according to the relevant specifications, standards and design requirements, and tile can be pasted only after it meets the requirements.
7) Tile. First, soak the tiles in clear water for 2 hours, and then take them out to dry. When used, they will be dry outside and wet inside. After the middle ash reaches a certain strength, you can paste the tiles. The mixture ratio of the paste materials used to paste ceramic tiles should be determined, that is, cement: sand = 1: 1, cement: 107 glue: water =10: 0.5: 2.6; At the same time, it is necessary to control the use time and use it as it is mixed. Pay attention to the fullness of mortar when pasting, to ensure that the paste is firm and not empty.
8) jointing: remove the residual slurry stuck at the joint of ceramic tile, spray water for wetting, and then use 1: 1 cement mortar for jointing. The jointing should be recessed into the ceramic tile 1mm, and the jointing mortar should be embedded tightly, and the joint should be smooth without air holes and joints.
9) Clean the walls. Use clean cotton yarn, wipe it clean and leave no dirt.
10) maintenance. After each layer of ash and ceramic tile is plastered, attention should be paid to maintenance.
2.5 Prevention and treatment of cracks and leakage in exterior wall painting
1) External wall compartmentalization leads to leakage. Exterior wall frame article embedded, mortar should be uniform, full, embedded firmly, dense.
2) Cracks on the exterior wall surface lead to leakage.
A. Before plastering the external wall, the oil stain and dust on the surface of the substrate should be removed; Uneven walls should be leveled with cement mortar, and smooth concrete walls should be roughened. Water in advance to wet 1d ~ 2d, and the wetting depth is 5 mm ~ 10mm.
B. Exterior wall plastering shall be carried out in layers, and the plastering thickness of each layer shall not be greater than10mm; After the final setting of each layer of plaster, the next layer of plaster can be carried out.
C ordinary portland cement or slag cement should be used for plastering mortar of external wall; Medium sand or coarse sand is yellow sand; Lime should be fully cured lime paste. D the whole plastering construction should avoid high temperature (temperature higher than 30℃) and low temperature (temperature lower than 5℃) seasons as much as possible; After the final set of each layer of plaster, it shall be cured by water spraying for 3 ~ 5 days.
3) Plastering admixture leads to leakage.
A. As the performance of micro-foaming agent is greatly influenced by dosage, configuration mode, ambient temperature and other factors, it is recommended not to use micro-foaming agent in exterior wall painting mortar.
B. Repair all kinds of cracks causing leakage in time to prevent the cracks from expanding further, and take measures: inject FISV360S structural adhesive into fine cracks, mix R42.5 cement and sodium silicate into coarse cracks, and compact the cracks.
2.6 Prevention and treatment of leakage in secondary decoration
1) In residential engineering design, holes (such as air conditioning pipe holes, smoke exhaust holes, solar water heater pipe holes, etc. ) can be reserved in the exterior wall to reduce the damage to the exterior wall by users during decoration.
2) After the housing project is put into use, the construction unit should strengthen the contact with users. If the house has property management, the property management department shall manage the decoration of the house and guide the residents to entrust qualified building decoration units for reasonable design and careful construction.
2.7 Prevention and treatment of temperature cracks and leakage on the top floor of the building. Cracks in the external wall of the top floor of a building generally occur at the windows of the external longitudinal walls at both ends of the top floor, which are splayed joints. Most crack only one end span, and a few crack two end spans; The first to second skin bricks under the roof ring beam have horizontal joints, the outer wall has corner joints, and a few lower outer wall ring beams have horizontal joints. The temperature cracks in the external wall are caused by the different linear expansion coefficients of concrete and brick wall in the roof, ring beam and gutter, and the former is twice as large as the latter. Only on the premise of effective heat insulation, heat preservation and setting reflective layer can temperature cracks be effectively reduced, dispersed and eliminated, and the measures to be taken are as follows:
1) adopts an effective thermal insulation layer and is provided with a reflective layer. Use materials with good thermal insulation performance and determine the thickness of thermal insulation layer according to local conditions. The black waterproof layer of flat roof and gutter is covered with aluminum foil and silver powder coating.
2) The indoor layout of the first bay at both ends should have good through flow.
3) Where temperature cracks often occur, steel wire mesh or plastic mesh should be laid on both sides of the wall, then cement mortar or mixed mortar should be used as the base, and then surface plastering should be carried out.
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