Analysis of the harm caused by the fall off of insulation layer of exterior wall

Shandong chuangyao Biotechnology Co., Ltd. is a professional manufacturer of hydroxypropyl methylcellulose. The falling off of thermal insulation layer of external wall brings more and more harm, which seriously threatens the safety of people's life and property. Recently, at the bottom of No.25 building of Longting Huaqingyuan community, Liyushan South Road, Urumqi, strong wind blew down the insulation layer of the wall. An 85 year old man sitting on the stone chair of the community was hit. When the 120 ambulance arrived, the old man had no sign of life.

Two days ago, the wall of No.7 building of a home in Huanggu District, Shenyang city fell off. Fortunately, although the falling insulation system knocked down the street lamp pole and cast iron fence, there were no pedestrians nearby, otherwise the consequences would be unimaginable.

The accident of external thermal insulation falling off has become a kind of building disease.

On the one hand, it is located on the sub surface of the building and is affected by many factors such as cold, hot, wet, heavy, water, wind and so on. On the other hand, building insulation is in the "full view of the public", in the information is extremely developed today, any quality problems will have a high exposure rate.

Characteristics of external wall insulation falling off

Some people in the industry said that the biggest feature of external insulation falling off is universality. The first is the universality of the responsibility subject. The external insulation has fallen off, covering almost all large developers, whether it is a central enterprise or a listed company; both domestic developers and foreign developers are not immune. Second, the universality of the region, especially in the cold regions, occurs in every city. Third, the popularity of the year, and is becoming more and more intense.

In addition to universality, there are several remarkable features

1. In terms of time, there is a phenomenon that "the old and the new are lost". That is to say, the falling off probability of insulation system completed after 2015 is far greater than that before 2015. Taking three projects with quality problems handled by Shenyang Construction Committee as an example, the longest three years and the shortest one year. Ten years ago or even earlier, Shenyang had a large number of XPS thermal insulation systems, and most of them are safe and sound.

There are probably two reasons for this phenomenon: first, the practitioners in the early external insulation industry have not learned how to fake; second, the new system which is surging in the late stage lacks scientific research support.

2. According to the system classification, the falling off probability of new materials is much higher than that of traditional EPS thin plastering system and high-grade rock wool thin plastering system. Such as phenolic system, extruded board system and foam cement system. Low grade rock wool shedding events also occur from time to time.

Although the shedding events of EPS system occur from time to time, the relative probability is still low due to the large absolute number of such systems.

The reason for this phenomenon is the lack of scientific research and technical support. Industry insiders said that as a big country of Shanzhai, China has copied things that have been formed in foreign countries, such as EPS thin plastering insulation system. If there is no foreign research in this area, China will basically rely on Mongolia, such as phenolic board, foamed cement board, rigid foam polyurethane board, XPS board, etc., all copy the EPS thin plastering insulation system. Due to the lack of scientific experimental data support, quality accidents occur frequently.

Foam cement insulation layer falling off in Shenyang Lotte Department Store

3. The falling off ratio of existing buildings is much higher than that of new buildings.

Energy saving and thermal insulation reconstruction of existing buildings is a project with higher requirements than that of new building technical standards and construction technology, because the strength of the existing building base wall and the quality of facing materials have changed greatly in the use process. The tensile bond strength of multi-level structural layers of the wall is different, such as the adhesive strength of putty, coating, wall and other different layers of coating veneer 。

Therefore, when the existing building energy-saving transformation, we must use the pull-out instrument to test the bond strength of the base, and the different materials of the same building should be measured separately to find out the weakest link, and take corresponding measures according to the evaluation of the situation of the base. However, in the real environment, due to the energy-saving transformation of public and civil buildings, sometimes it is more confusing than the new buildings, so accidents are inevitable.

Cause analysis of building insulation falling off

（1） External factors of market environment for building external insulation

A supervision system in name only

After the construction unit enters the site, it needs to apply for the re examination of materials, which is an important link to ensure the construction quality and safety. Taking thermal insulation materials as an example, construction units need to pay high testing fees one by one. Since every building has been picked up, since the inspection should be on-site sampling and core drilling sampling on the wall according to the inspection batch, but in reality, this is not the case for individual sites. Therefore, in some cities, in addition to increasing the burden of construction enterprises, the construction quality is rarely guaranteed.

2. The construction unit that pays close attention

For example, most civil buildings in Shenyang require the use of B1 grade 20kg benzene board for thermal insulation. The minimum cost per square meter including (value-added) tax and erection is 105-110 yuan, but the market quotation is often only about 80 yuan. Moreover, the developers and owners are slow to collect money, which excludes the regular enterprises from the market, and a large number of enterprises that start from other ways are full of them, resulting in a mixed situation of good and bad in the industry.

3 unreliable general contractor

In order to save the cost, some general contractors did not plaster and level the shear wall after removing the formwork, and even did not deal with the release agent. And thermal insulation construction enterprises won the bid at a low price, and simply can not afford the cost, so simply stick the insulation board to such a wall, the results can be imagined. There are some general contractors who are looking for plastering