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The nature of the subsoil linked to climatic hazards combined with undersized or inappropriate foundations can destabilize a house, resulting in settlements, cracks, etc. Various methods can correct these problems without having to demolish and degrade his home.

Injecting resin to stabilize the foundations

Necessary material

  • Polyurethane resin to be injected
  • Steel injection tubes
  • Safety caps for injection tubes
  • Laser level
  • Chipping perforator
  • Workshop truck connected to the injection gun

Difficulty: 4/4
Cost: approximately € 15,000 (internal and external treatment by a specialized company)
Time: 1 day and a half

Made partly on the ground and on the basement, this house is the victim of differential settlements due to the presence of clay soil with low mechanical resistance. These lift defects result in cracks in the front façade, the sprocket, the inner lining, and voids plinths.

Work reserved for pros

Several foundation reinforcement techniques exist: micropiles, concrete pads, resin injection, etc. But this type of intervention is reserved for specialized companies. On this site, it is the injection of resin which was retained. With this technique, even the furniture does not have to be moved: the intervention mobilizes only small areas at a time, treated surfaces being immediately reusable. As a first step, a technician studies the most appropriate repair solution. Network identification is carried out in order to check the good condition of the pipes and to check the possible presence of underfloor heating network or electric cables. The actual work here required a team of three people for a day and a half. The first phase concerns the intervention on the foundations while the second phase allowed to treat the raising of the slab of the stay.

Focus on non-destructive techniques

The technique consists in consolidating the soils in depth using a two-component expansive resin. Injected in the liquid state, the resin diffuses in the slightest crevices of the ground before expanding and solidifying while compacting the ground. If necessary, the foundation, wall or paving can be removed by continuing the injections. These are carried out by continuously monitoring the reaction of the structure until it is completely stabilized.

Site preparation to stabilize the foundations

Cracks on façade wall

  • Caused by the movement of the foundations, the cracks in stairs follow the joints of the masonry blocks.

Determine the injection levels to be done

  • The company carries out the tests which make it possible to calculate the resistance of the ground.
  • Performed at regular intervals, they determine the injection levels for each piercing.

Drill the ground with a hammer drill

  • Drill holes of Ø 18 mm are made every 45 cm at the perforator-chisel, with an angle of 10° with respect to the wall, in order to optimize the penetration of the expansive resin.

Insert steel injection tubes into the ground

  • In each of the holes that will be used to route the resin injected into the ground, the operator introduces, by hand or by "vibro-sinking" - with the help of the perforator in percussion mode - the steel injection tubes.

Put caps on the tubes

  • Safety caps are placed at the end of each tube to prevent technicians from getting injured during the operation.

Follow the resin injection

  • The use of a laser level makes it possible to follow in real time the effect of the resin injections, but also to monitor the overall behavior of the building.

Injection of the resin into the foundations

Injection of the resin into the soil

  • The injection of the resin in the liquid state allows its diffusion in all the voids and interstices.
  • The main goal is to stabilize the structure, which is reflected here by a surface reaction of 2 to 3 mm maximum.

Injection of the resin into the soil

  • The term lifting is used when one reaches or exceeds 4 mm.
  • Removable protection protects the wall from dirt where the resin is injected.

Cut the injection tubes

  • Injections are stopped as soon as the building is stabilized.
  • The injection tubes are then cut at the base and the holes are filled.

Polyurethane resin

  • The polyurethane resin is formulated to have a limited thrust, the final expansion being made after a few seconds.

Staple cracks

  • Within two to three months after the operation, the cracks are stapled.
  • Stapling consists of widening the crack, making perpendicular cuts to seal twisted irons (Ø 8 or 10 mm) and covering them with a resin mortar without shrinkage.
  • For covers on the facades, it is recommended to wait one year before applying a fiber-coated.

Interior floor leveling

Cracks inside

  • Inside, the foundations' movements and the sloping of the pavement caused significant cracks in the linings.

Crack in the ground

  • They also result in spaces of several millimeters between the floor covering and skirting boards.

Spot the networks

  • Technicians identify any networks present in the work area before determining the location of the injection mesh.

Drill the joints of the tiles

  • Piercings (Ø 6 mm) are made in the tile joints.
  • They must cross the floor covering, the screed and the slab.

Inject resin inside

  • As for the external treatment, the technician then introduces the injection tubes that will be used to convey the resin under the interior floor of the workpiece.

Injection of the resin into the soil

  • The operation starts with the injection of resin while controlling the lift at the laser level with a precision of the order of half a millimeter.

Protect the soil during resin injection

  • During the intervention, a protection is also arranged around the injection tubes to protect the floor covering.

Fill the holes with mortar

  • Once the treatment is complete and the tubes are cut at their base, the holes are closed with a joint mortar equivalent to that of the original seal.

Before / after a resin injection

  • After surgery, cracks are most often reduced, as seen here between the pre-injection phase and after.
  • As for the exterior, the company advises to wait one year before undertaking repair work, the time that the building is perfectly stabilized.

Video Instruction: Underwater resin injection