External wall insulation refers to a kind of insulation material used for wall construction. It is mainly composed of polymer mortar, glass fiber mesh cloth, flame-retardant molded polystyrene foam board or extruded board and other materials. Thermal insulation, waterproofing, and decorative functions are the preferred materials for the external insulation of modern buildings. At present, with the popularization of exterior insulation systems in the domestic market, various forms of project quality problems have gradually emerged. During the construction process, the insulation system will cause quality problems due to the weather conditions at the construction site, construction personnel's operation level, and construction techniques. Frequent problems are mainly reflected in the following aspects: The appearance of the surface is poor and the appearance quality is poor. Insufficiency caused leakage and leakage, and the paste was not strong enough to cause the external wall tiles to fall off. The practice was not standardized to cause wall cracks. Today, I would like to talk about the external wall insulation construction plans and procedures, as well as the common problems of external wall insulation construction and preventive measures. I hope to help you!
External wall insulation construction scope
1. The scope of application of this regulation: Polystyrene board is used as insulation material, polymer adhesive mortar is used as bonding material, polymer screed mortar is used as wiping layer, and alkali-resistant glass fiber is coated with plastic mesh as reinforcing material and supplemented with card. Construction and acceptance of external insulation systems for external and external walls of industrial and civil buildings anchored by nails.
2. Requirements for product materials: The technical performance of all materials used in external wall insulation construction should meet relevant national standards.
3, construction personnel requirements: According to the project size and schedule requirements, organize the construction team. Prior to the start of construction, the construction personnel will be educated in thoughts, techniques, quality, and safety in order to ensure the quality of the construction project and the progress of the project.
4. Requirements for construction environment: The normal construction operating environment temperature for exterior wall insulation construction is 5°C~35°C.
External wall insulation construction requirements
1. The construction and acceptance of the exterior wall and exterior doors are completed, and the base surface meets the requirements of relevant regulations.
2. The ambient temperature for the normal construction of external insulation systems is 5°C~35°C.
3, the construction site should be to achieve road access, water, electricity.
4. Construction erection tools and scaffolding shall meet the construction requirements and be safe and reliable.
5. The mobile distribution box and tap water pipes used in construction shall be configured according to the construction requirements.
6. Vertical and horizontal transport facilities for distribution materials are required to comply with relevant safety regulations.
7. The distance between the high-voltage electric wires and the construction site in the construction operating environment shall comply with relevant regulations and have corresponding protective facilities.
8. Remove all obstructions on the wall surface to be insulated.
9, the wind when the insulation board is not more than 5 levels.
10. To ensure construction quality, the construction surface should avoid direct exposure for a long time, and it should not be constructed in rainy days.
11, construction tools: slotting machine, wallpaper knife, screwdriver, scissors, ink fountain, brown brush, electric mixer, plastic, mixing barrel, impact drill, hammer, trowel, pallets, 2m on the ruler.
External wall insulation construction points
1, grassroots cleanup.
2, wall measurement, bomb line, hanging line.
3, paste the package mesh.
4, paste the polystyrene board.
5, the anchor is fixed.
6. When the surface of the polyphenylene plate seam is uneven, it needs to be roughed with wood-lined coarse sandpaper.
7, wiping the bottom surface plaster.
8, paving grid cloth.
9, smear layer polymer mortar.
10. Acceptance.
External wall insulation construction quality acceptance standards
1, construction quality inspection methods and standards
(1) After completion of each procedure, check the flatness of each direction with a 2m flat panel and check the verticality with a line falling ruler. The standard deviation between vertical and entrainment is no more than 3mm.
(2) The deviation of the thickness of the insulation layer is checked by acupuncture, and the actual thickness of the insulation core board is determined to meet the design requirements.
(3) random sampling inspection, every 100m2 sampling points, if the point does not meet the design requirements, increase the sampling checkpoint to set a point every 30m2, and make records, to be used for mathematical statistics, quality assessment.
(4) The quality control inspection during construction operations shall be conducted by the quality inspector. The entire process of construction quality shall be controlled, and the quality of the process shall be controlled with emphasis, and the next process shall be carried out after passing the inspection.
2, project quality assessment acceptance criteria
(1) The surface of the wall surface is smooth and smooth, there is no trace of repair, there is no contact, and the appearance is good.
(2) The vertical angle of the yin and yang corners meets the quality requirements. The allowable deviation of verticality and surface flatness of the facade shall comply with relevant regulations.
3, the whole wall surface without hollowing, no cracks, no spots, uniform color.
External wall insulation construction process acceptance
1. The varieties and technical performance of various materials entering the site shall meet the design and product quality requirements.
2. The structure of each layer of the insulation system should meet the design requirements and related technical regulations or atlas specifications.
3, protective layer without hollowing or cracking phenomenon.
4. The grid cloth is in close contact with the insulation layer and there is no warping phenomenon.
External wall insulation construction common problems and preventive measures
1. Poor surface appearance resulting in poor appearance
The reasons for the uneven surface appearance and poor appearance of the exterior wall and their preventive measures are mainly the following:
1.1 Storage and storage of materials
The exterior wall insulation system consists of a wide variety of materials, each of which must be carried out as required. The most common insulation boards in many construction sites are stacked in the open air, and the sun and rain can easily cause deformation and shrinkage of the board structure, affecting the formation of the wall surface. In particular, in the summer when the temperature is high, the EPS board is affixed. Excessive exposure and exposure time may cause deformation of the EPS board and cause unevenness of the wall surface. Preventive measures: According to the characteristics of the external thermal insulation construction, advance the construction plan for the flowing water and organize the construction personnel to ensure that the follow-up procedures are inserted in time.
1.2 Effect of Substrate Treatment Not in Place
In the construction process, there are often cases where the substrate is not treated or is not in place. In particular, unevenness occurs after running the concrete wall. In the actual construction process, it is generally not willing to deal with, resulting in uneven thickness of the EPS board adhesive. As a result, the subsequent deformation is not uniform and the wall surface irregularities are formed. Preventive measures: The treatment and inspection of the substrate must be done to ensure that the substrate is flat, solid, and clean.
1.3 Influence of Anchor Bolts in Construction
A large number of clearly visible circular impressions are often seen on many exterior insulation walls. This is an appearance quality defect left by the improper construction of anchor bolts. Preventive measures: According to the thickness of the external insulation to select the appropriate length of the anchor bolt, and in the construction of the anchor bolt to ensure that the anchor cap can be slightly lower than the insulation board 2mm or so.
1.4 Influence of Low Level of Construction of Professional Teams
At present, the quality of construction teams is uneven, the construction level of low-quality construction teams is poor, construction quality is difficult to guarantee, and quality problems such as poor surface smoothness are caused. Preventive measures: strengthen management, conduct surveys on the construction of professional teams and projects that have been completed and delivered for use, and conduct a strict review of their qualifications for construction and training of laid-off workers, and choose a sound construction quality management system, social reputation and services. Good quality professional team.
2. Causes of leakage and leakage of detailed nodes and preventive measures
Under normal circumstances, the actual situation of the insulation site is relatively complex, it is difficult to specify in the design drawings, the professional team must be painted in different parts of the site of the insulation node large sample plan, reported to the relevant units for approval before the construction.
Causes of leakage and leakage and preventive measures are mainly in the following aspects:
(1) The construction of sub-racks does not require slotting and inlaying to cause leakage and leakage. The setting of the grid partitions on the external thermal insulation wall is mainly to overcome the structural measures taken to overcome the large continuous surface area of ​​the thermal insulation wall and to be easily cracked under the influence of high and low temperature. Preventive measures: The setting of the dividing line should be minimized. In the construction of the dividing line, a special slotting device should be used to cut the insulating plate into notches, and the EPS plate must not be cut through and then inlayed.
(2) The external insulation forms a "dawn seam" on the top of the parapet wall or window sills to cause leakage and water leakage. In the design, no general consideration is given to the external insulation at the top of the parapet or at the sill of the parapet, and only relying on the insulation construction to strengthen the counter-mouth. However, in the actual construction and use, the above-mentioned parts are often damaged by stamping and causing leakage and leakage. Preventive measures: In the above areas, it is recommended to make concrete at the outer insulation joint or use thermal insulation mortar to press the top, and then reinforce the grid cloth anti-wrapping and anti-crack mortar mortar.
(3) Insufficient leakage and leakage due to irregular installation and closing of external wall windows. There are two methods for installing the external wall window, namely the first plug and the second plug. In the outer wall of the external thermal insulation construction, due to the improper closing or fixing of the window frame, it is easy to cause leakage and water leakage. Preventive measures: In order to ensure the quality of exterior wall holes and reduce leakage points, post-plugging can be used to strengthen the inspection and control of the construction quality of the openings. When installing the external wall window, avoid direct drilling and fixing on the lower frame of the window frame.
(4) After construction, wall rainwater pipes, blinds, and fixed components cause leakage and leakage. Preventive measures: should be done before the construction of the external insulation.
3 paste is not strong cause the outer wall to fall off
(1) Leveling the mortar and emptying the main wall, especially if the water seepage for a long time, it is prone to continuous expansion of the empty drum, which will cause the insulating layer to be accompanied by hollowing or partial destruction. Preventive measures: Before the construction of the insulation layer, check the quality of the screed and find that empty drums are handled in time.
(2) The unsatisfactory quality of the trowel mortar caused a large area of ​​the outer wall to fall off. The adhesive mortar did not enter the site for re-examination. The use of unqualified raw materials had poor adhesion. Preventive measures: Strengthen the quality control of raw materials entering the market, do a double check of incoming materials, and do a good job in advance.
(3) Insufficient amount of binder caused a large area of ​​the outer wall to fall off. Preventive measures: Training of on-site quality inspectors requires that, on the basis of understanding the structure of the insulation layer, the on-site detection methods should be clearly understood. In the premise of ensuring the quality of the adhesive, the control of the adhesive area: the effective adhesive area ratio of the wall insulation board of the multi-storey architectural paint under 7 layers shall not be lower than 40%, and the effective adhesion area rate of the 7-layer and 7-storey architectural paint wall is not Less than 70%, when the floor exceeds 7 floors, an I-shaped metal-insulated transverse band shall be provided in the 7-18-story compartment, and an I-shaped metal-insulated transverse band shall be provided for each of more than 18 floors.
(4) The insulation board density is too low to meet the surface load bearing capacity requirements, XPS board damage. Preventive measures: The density of polystyrene board requires more than 18kg. Entering the inspection inspection certificate and factory inspection report, and spot checks for retest.
4 practices are not standardized caused by cracks in the wall
The main reasons for the cracks on the external walls and preventive measures are mainly the following:
(1) Directly using cement mortar as anti-cracking protective layer: high strength, large shrinkage, insufficient flexible deformability, causing cracking of the mortar layer; the prepared anti-cracking mortar has been modified with a polymer, but is not flexible enough or resistant The cracked mortar layer is too thick; the sand particle size is too fine, the mud content is too high, and the grain size distribution of the sand is unreasonable.
Preventive measures: The use of a low-alkali type high-softness external insulation surface layer will greatly increase the service life of the grid cloth, thereby effectively reducing the occurrence of cracks.
Ensure the smoothness of the surface of the insulation board, and effectively control the thickness of the anti-cracking mortar; select medium and coarse sand with mud content within 3%.
(2) The use of unqualified glass fiber mesh fabrics such as: low breaking strength, low retention of alkali-resistant strength, large strain at break, etc.; the amount of alkali-resistant coating applied on the grid cloth is insufficient.
Preventive measures: Use alkali-resistant alkali-resistant grid cloth or alkali-resistant grid cloth.
(3) Problems in construction operation 1 The grid fabric is not properly laid in the surface layer, and is too close to the inside; the size of the grid fabric is not overlapped or overlapped; the size of the grid can not meet the requirements of the specification; 2 The window periphery and wall transitions Stress-concentrated parts are not provided with reinforcing mesh cloth; 3 mesh cloths are laid directly on the wall when the bottom glue is applied. The glue and the mesh cloth cannot be well compounded, making the mesh cloth Less than necessary constraints and dispersion; 4 insulation board surface is uneven, especially the adjacent board surface is uneven, the gap between boards is filled with adhesive; 5 when the insulation board is pasted, partial seams appear or there is no set cut in the four corners of the window; 6 In the cut-off part of the insulation system due to the improper waterproof treatment of the different material materials; 7 When the surface layer is applied under the sun exposure, or after the surface layer is wiped in high temperature weather, the water is not promptly sprayed, resulting in dehydration of the surface layer. Too fast; winter construction at low temperatures, anti-freeze measures are not in place, due to deformation caused by frost heave.
Preventive measures: According to the actual construction progress of the project and the weather and temperature conditions, do a good job of technical disclosure, conduct technical training for professional teams, and strictly follow the norms and operating procedures for construction. Do a good job of follow-up inspections and find that problems are corrected in a timely manner.
(4) The use of rigid putty, putty flexibility is not enough; the use of water-resistant putty, when immersed in water after foaming cracking; the use of paint film hard coating, paint elongation at break is very small.
Preventive measures: The crack resistant exterior wall putty has a good anti-cracking and anti-cracking effect. The external wall anti-crack putty has excellent waterproof performance and good air permeability, which can prevent the entry of water molecules. Reducing the presence of water molecules at the base can effectively prevent alkalization of the anti-crack cement mortar and increase its service life. The decorative coating is made of elastic paint, which can effectively prevent cracking and shedding of the decorative layer.
Editor's summary: The above is the vigilance: External wall insulation construction common problems and preventive measures Non-flammable insulation materials are the preferred related presentations. From the existing quality problems of exterior insulation systems, it can be seen that most of the quality problems are due to the construction site does not press The corresponding technical specifications require construction. Therefore, strengthening the external wall insulation construction supervision can reduce the quality of hidden dangers.
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