The problem of buildings suffering from weak or unstable soils is becoming increasingly acute in Lithuania. And while centuries-old buildings can also provide surprises, new buildings are leading the way in terms of design and construction errors. „Our absolute record was set when we had to deal with a sinking floor in a private house that still smelled of paint, and the residents hadn’t even moved in yet,” says Valdas Kordušas, an engineer at Geolift Baltic. He explained what causes such problems and listed the signs that indicate that a building is on unsuitable ground when buying a home. He also revealed the worst that can happen if the problem is not addressed.
Why do soils become unstable?
Although engineering geological and geotechnical soil investigations have been mandatory since 2011 for special buildings and since 2017 for non-extraordinary buildings, unstable or weak soils are still the most common cause of sinking floors or foundations. According to Mr Kordusas, the most common cause of soil-induced stability problems in new or relatively new buildings is due to the designers’ mistakes, as they did not properly assess the geological conditions and did not plan appropriate structures. Builders also make mistakes.
Examples of construction defects include soils that are full but not properly or sufficiently compacted. There are also engineering accidents where the soil is washed away, for example, due to a leaking water main, although there is only one rule to prevent such problems – no joints under the floor. However, it is quite common to save a few tens of euros when laying a pipeline, only to have to tear up the floor to find the leaky junctions, repair them, then fill in the voids and stabilise the soil, and, in most cases, lift the settled floor, said V. Kordušas. “Older buildings are starting to crumble due to natural disasters and other radical changes and events in the environment. For example, there have been cases in the Old Town of Vilnius where builders have used piles instead of the more expensive drilled piles, and all the surrounding buildings have started to fall apart before our eyes”.
How do you recognise problems in a building?
Even if you are not a professional builder, it is possible to see certain signs of a floor or foundation sinking with the naked eye. Of course, provided the building has been standing for at least 3-4 years, although there are cases where problems have come to light in brand new buildings.
When choosing a home, it is recommended that you first go round and look at all the walls, both inside and outside. And if they are cracked, it’s a good idea to call in an expert to find out whether it’s just the use of inappropriate building materials or whether the problem goes deeper than that, reaching down to the foundations.
We can see from the location of the cracks what is causing them and what is happening to the house. For example, he says that if “the cracks are in one corner of the house, in both walls, it’s already a problem with the foundations. Even if the property is a multi-storey building, every house has foundations, and the problems they cause, if any, will reach the flats on all floors and their occupants, so it’s a good idea to go around the house and look at the walls, even if it’s only on the ground floor or the ground floor, from the outside.”
As an example of the problems faced by multi-storey buildings due to unstable soil, Kordušas cited a case in which the columns supporting the balconies of several blocks of flats in the Fabijoniškės district of Vilnius collapsed, dragging the external walls along with them. „After an expert examination, it was decided to immediately reinforce the soil under the pillows to stop further decay,” he says.
When inspecting a building for possible floor settling in an individual house, especially if it is already furnished, it is recommended that you pay attention to the skirting boards, the transitions between rooms, the kitchen furniture, which has a fixed position, and to check that everything is level, that there are no gaps between the skirting boards and the floor, the furniture, and that there are no large gaps in the bathroom. „For example, if you see a centimetre of silicone between the wall and floor tiles in the bathroom, you should take note of that. This is because larger amounts of filler can indicate hidden problems,” he warned.
The solution - geopolymer injections
Floors and foundations settle for different reasons and are therefore treated using different technologies. „For example, in the case of floors in individual houses that are sinking, they are lifted up, and the soil under the floor is stabilised and reinforced to prevent further sinking. We use geopolymer injection technology, where geopolymers capable of lifting floors or entire buildings are injected to the required depth through small drilled holes, with virtually no disruption to the family’s life,” said V. Kordušas. And while the process is similar for both sinking floors and sinking foundations, and it usually comes down to the soil, each situation is individual, so our first goal is to find out what caused it and work exactly where it needs to be to solve the problem once and for all.
Failure to clean up could lead to emergency situations
If the root cause of the problem is not addressed, i.e. by dealing with the soil, residents have to have their floors repaired every ten years on average. Each time, the floor is broken up and replaced, most likely by re-routing heating pipes and electricity, as it is very easy to damage them during the work.
If nothing is done with sinking foundations, it can lead to even more trouble or even tragedy – the house or part of it may simply collapse. “Every building can move up to a certain limit, and when those limits are reached, the building is no longer safe to use. By the way, private houses are a bit more lenient because they do not have a high concentration of people. Apartment blocks, on the other hand, have to be maintained regularly. If changes are noticed, they must be monitored – the process and progress must be recorded, and if the problem is dangerous or considered potentially dangerous, it must be eliminated,” emphasised V. Korduš.
He also pointed out that although geopolymer injections have been widely used recently to solve soil and building stability problems, there are cases when it is more cost-effective to demolish a building, clean up the soil, and then rebuild it. Therefore, checking whether the building is free of soil problems when purchasing a home is also financially prudent.