Sinking houses caused by absence of proper initial surveys, expert says

Many houses in Ho Chi Minh City are sinking and at a high risk of collapsing due to mistakes in design and construction which were caused by the absence of proper initial surveys.

A boy stands at the site of a riverside house in Binh Thanh Districts, which collapsed due to weak soil (Photo:Phan Hien)

Dau Tu Tai Chinh Newspaper has caught up with Nguyen Van Cu, director of the construction firm Anh Kim, to interview about his points of view and solutions for the issue.

Dau Tu Tai Chinh: What are the causes of sinking houses in Ho Chi Minh City?

Nguyen Van Cu: Sinking houses are appearing in many districts including District 2, 6, 7, Binh Thanh, Hoc Mon and Binh Chanh. Many old houses and even newly-built ones experienced the problem.

Earlier, the foundation was built by wood poles as we did not have the technique for making concrete poles with iron or steel wires built-in to their core. Therefore, they easily sink when being built on weak soil.

Despite the concrete poles and technical drawings, constructions now still face a similar problem as builders do not make proper initial surveys before starting their works.

Statistics show that haft of 10 sinking houses have foundation that is built by concrete poles. People usually believe those kind of houses are firm and sound, but actually the houses can still sink if the poles cannot stand the house’s weight.

What is the solution for sinking houses?

We will have to make a survey on the houses’ condition to find out an appropriate plan to fix it. We also examine adjacent houses’ foundation to find out which materials builders used to make poles, how deep the poles are and how their loading capacity is.

Of course, different houses’ conditions have different solutions. Many construction companies now opt for electrical hydraulic jacks with high capacities to lift sinking houses. It takes around 70 days to fix a big sinking house. 

Does the fixing make any impact on the houses’ condition?

In theory, builders are not allowed to make any mistake when repairing a construction, which is damaged already or has technical errors.

We have fixed some tough constructions, including lifting up six houses in row with a total weight of 3,000 tons by one meter higher in residential zone Binh Hung in Binh Chanh District.

We also lifted up a sinking villa by 1.3 meters in District 2 and strengthened foundation of another villa in the same district.

What are the risks of rescuing nearly-collapsed houses?

The most potential danger we carry is to fix 5 or 6-storey houses at the corner of crossroads or T-junctions, with balconies leaning over into the street.

Those houses will easily collapse if we make just a minor mistake. The principle of fixing sinking houses is not to be too subjective.

By Trieu Nhan and Minh Tuan – Translated by Vu Minh

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