A house settling on soft soil isn’t unusual in Banjarmasin. A floor that used to be level now tilts to one side, doors start to jam, diagonal cracks appear at window corners, and the terrace pulls away from the wall. After the rainy season, water gets in more often than it used to.

Owners usually ask straight away: can it be fixed, how much will it cost, and does it have to be demolished? The answer depends on the cause. This article covers the repair options common on soft soil and how to judge whether a contractor’s offer makes sense. How to read the signs is in reading wall cracks and ground settlement, and the foundations commonly used are in how to check a house foundation.

First step: find the cause

Patching cracks before you know the cause often wastes money. Some causes common on soft soil:

  • The soil underneath compacts slowly under the weight of the house, sometimes over years.
  • The fill under the floor sinks, especially if it wasn’t compacted. See buying filled land.
  • Uneven settlement because an extension has a different foundation from the main house.
  • The water table drops, so wooden cerucuk piles are exposed to air and rot, or peat shrinks.
  • The load increases, for example adding a floor or fitting a big water tank without checking the foundation.
  • Water flow that erodes the soil around the foundation, for example from a leaking drain or a gutter that discharges against the wall.

Start by monitoring cracks the simple way: mark the ends, measure the width, add a date, and repeat after a few weeks. A still crack is different from one that keeps widening. This is covered in more detail in the crack article above.

When you need a structural engineer

Call a civil or structural engineer if:

  • diagonal cracks appear at several openings,
  • there are cracks in concrete columns or beams,
  • the floor clearly tilts or many doors jam the same way,
  • cracks come back after being patched,
  • you plan to strengthen or extend the building.

The engineer will look at the condition, estimate the cause, and recommend a sondir test (a soil bearing test using a sondir rig) if needed. The result is the basis for choosing a method and comparing quotes. Fixing a foundation after the house is built is usually complicated, so don’t rely on one contractor’s guess.

Common repair options

A general picture follows. Not every option suits every house.

1. Patch and monitor

If the settlement is small, the cracks are hairline, and they aren’t growing, patching, repainting, and checking again after the season changes is enough. It’s the cheapest option, but only makes sense if the movement has really stopped.

2. Raising the floor

If the floor is lower than the road or often floods, it can be raised with fill and a new slab or tiles. Things to account for:

  • Doors, windows, and sockets end up lower than the new floor and need adjusting.
  • The weight of new fill adds pressure on soft soil. If the soil below is still sinking, the new floor can sink with it.
  • The joint with walls and foundation needs attention so no gap opens.
  • Drains and the septic tank may change level too.

Raising the floor solves flooding, but it doesn’t stop soil that is still moving. Treat it as a height fix, not a foundation fix.

3. Adding cerucuk or piles under the foundation

This strengthens the existing foundation with extra piles, either galam cerucuk (short piles of galam wood) or small concrete piles (mini piles). The idea is to pass the load to a firmer layer or add bearing capacity to the soil.

A few notes from local research:

  • Galam wood is widely used in Banjarmasin to strengthen soft soil and works well as long as it stays submerged in groundwater. A study in the Info Teknik journal of ULM covers shallow foundations strengthened with galam cerucuk.
  • Small concrete piles usually have higher bearing capacity, while galam cerucuk is generally cheaper and enough for certain loads. Figures in studies depend on the site and its sondir results, so don’t use them as a benchmark for your house.
  • Installing piles under a house that already stands needs working space, small equipment, and a way to carry the load temporarily. Not every contractor has done it.

4. Separating or strengthening an extension

If only the kitchen or an added room has settled, an engineer may suggest separating it from the main building with a joint that can move, or strengthening its own foundation.

5. Demolishing part or all of it

For serious damage, including badly cracked structure or large settlement, rebuilding can make more sense than patching. Demolition may also be chosen for a timber house whose posts are rotten throughout. Timber house care is covered in maintaining a timber house.

Stop the cause too

A structural repair fails if the cause is left alone. Things often done alongside:

  • Fix the drainage. Rainwater should flow away from the foundation, and gutters shouldn’t discharge on the soil beside a wall. See checking drainage.
  • Check for pipe leaks around the house that can wash soil away.
  • Keep the water table around wooden cerucuk so it stays submerged.
  • Reduce load on weak parts, such as a tank on top of the kitchen roof.

For building on wet land, see building a flood-resistant house in swamp areas and housing characteristics on Banjarmasin’s wetlands.

Judging the cost

We don’t give rupiah figures because there is no sourced benchmark we can rely on for foundation repair in Banjarmasin. Cost depends heavily on:

  • the area and part of the house being repaired,
  • the method chosen,
  • the depth of the firm ground layer,
  • access for equipment and materials,
  • whether the house has to be emptied,
  • whether a sondir test and an engineer’s drawings are needed.

How to judge a quote:

  1. Ask for the scope in writing. What will be done, how many points, what materials, and what sizes.
  2. Compare the same scope. Two quotes using different methods can’t be compared by price alone.
  3. Ask about warranty and limits of liability. What happens if the house settles again.
  4. Have a structural engineer review the quote before you agree. The engineer’s fee is small next to the cost of the wrong method.
  5. Avoid paying in full upfront. Pay in stages as work progresses.

Tips on choosing who does the work are in choosing a house contractor, and a comparison with building costs is in calculating the cost to build a house.

Permits and neighbours

Changes that touch the structure usually involve a Persetujuan Bangunan Gedung (PBG, the building approval that replaced the old IMB). Ask the building permit office in your city before you start. See also understanding PBG, the successor to IMB. If the house adjoins neighbours, tell them. Driving piles causes vibration and noise.

If you’re weighing a purchase or a sale

A buyer of a second-hand house who finds signs of settlement can ask for an expert assessment first and use it to negotiate. A seller whose house needs repair can read selling a house that needs renovation.

Closing

A house that has settled on soft soil doesn’t automatically have to be demolished, but it isn’t enough to just patch it either. Find the cause, monitor it, get a structural engineer’s assessment, then choose a method that fits the soil and the load of the house. If you’re looking for a house in Banjarmasin and want company on a survey, the Vorneo Property team can help through the contact page.