Replacing the foundation under a wooden house – methods, technical nuances

Replacing the foundation under a wooden house

The subsidence of the foundation of wooden structures is a frequent occurrence. This process comes from various kinds of hydrological and physico-mechanical changes in the lower soil, which reduce its bearing capacity. Often, changes in soil properties are caused by construction work being carried out on a personal territory. Under these conditions, replacing the foundation under a wooden house becomes the only way to prevent further subsidence, leading to destruction.


  • Replacing the old foundation: ways
  • How to choose a new foundation for a wooden house?
  • The main stages of replacing the foundation
  • Stage 1. Installation of jacks
  • Stage 2. Rise of the house
  • Stage 3. Making the foundation and removing the jacks

Replacing the old foundation: ways

There are several types of foundation replacement under a wooden house:

Replacing the foundation of a wooden house

Replacing the foundation of a wooden house – the second life for the building


Lifting a house on jacks

Jacks not only greatly simplify the process, but also allow you to raise the house evenly

  1. Cosmetic – the easiest way, not involving significant financial investments. In this situation, the rotten area is simply cut out, and a suitable wooden element is inserted instead. But it should be noted that with such a partial replacement, the integrity of the house is inevitably violated.
  2. Wall dismantling – type of construction work, involving the complete dismantling of the walls, after which the lowermost crown of the log house is replaced. The method is reliable, but it requires a lot of patience from the masters and time for disassembling and assembling the structure.
  3. Foundation disassembly. To do this, remove the 20 cm layer, replace the wooden crowns and restore the foundation.
  4. Replacing the crowns by lifting the structure with a jack – the most popular method that allows you to replace the foundation quickly and efficiently.

Important! The above methods of replacing the foundation require the use of different tools that need to be prepared in advance so as not to be distracted by the search for suitable equipment. So, the cosmetic method can be implemented with only a chisel, sledgehammer and hacksaw in the arsenal.

Dismantling the foundation will require a device with which it will be possible to realize the task. The choice will depend solely on your preferences and technical capabilities.

You should also worry about the temporary supports on which the house will be held during the repair.
If you intend to use jacks, their number, depending on the length of the walls, can vary from two to ten.

Jacks for lifting

Depending on the length of the walls, the number of jacks varies from 2 to 10

How to choose a new foundation for a wooden house?

It is important to understand that replacing the foundation of a house is a process that requires careful preparation. First of all, you should decide on the design of the future foundation, which will replace the old one. There are the following types of foundation for wooden houses:

    • Column foundation – a structure adapted to support relatively light houses with panel, frame or wooden walls that do not create a significant load. Despite its apparent simplicity, the columnar foundation is a sure way to provide reliable support for a garden or summer house, a light bath or a low-rise country cottage. It is represented by a system of poles that are installed in places of maximum load, i.e. at the intersection points of the walls. The posts are made of brick, concrete, stone and are mounted at a distance of 1-2 meters from each other.
    Column foundation

    Column foundation is the surest way to provide reliable support

      • Bored pile foundation – a kind of columnar foundation, only asbestos-cement pipes filled with a special mixture are used as bearing components. The construction of such a foundation consists of piles and a grillage connecting them. Bearing elements are located under the most significant points of a wooden house, for example, at the corners of a building or at the intersection of major walls. Bored pile foundation is optimal for buildings on high water soils.
      Bored pile foundation

      A bored pile foundation is a great but expensive option

        • Pile screw foundation – the most interesting type of base, intended originally for military purposes. The foundation is valuable in that it can be used on any site, even uneven. Low price and the possibility of repeated use of screw piles – additional advantages to the piggy bank of advantages.
        Pile screw foundation

        To build a pile-screw foundation, you will need special construction equipment

        • Strip foundation allows you to build heavy houses and at the same time provides a good level of reliability and security. Shallow strip foundation is divided into monolithic and precast. The first consists of concrete based on formwork, the second – from concrete and reinforced concrete blocks.
        Strip foundation

        Shallow taped foundation – the best option for small buildings

        The main stages of replacing the foundation

        In order for the replacement of the foundation to be performed efficiently, it is necessary to follow the sequence of steps.

        We will consider the most common type of replacement – using jacks.

        Stage 1. Installation of jacks

        Jacks allow you to raise the house evenly, otherwise (with uneven lifting) the logs of the lower trim will bend, which leads to their separation and breakage. The jack must be installed in places where the wood is not damaged by rot. Do not forget to install gaskets – steel plates (5 mm) – this is necessary for the correct transfer of force from the jack rod to the logs.

        Stage 2. Rise of the house

        Raise the wall to a height of at least 6 cm, remove the rotten extensions and lower the structure to trim the bars placed on the end – temporary supports. Between the bars and logs, an antiseptic-treated tow is laid in width equal to the double thickness of the wooden beam. Under the proposed foundation tape, a brick fight is poured and a 10 cm layer of gravel.

        House lift

        Start of work – lifting the house on jacks

        Stage 3. Making the foundation and removing the jacks

        After the log house is safely lowered to the brickwork, they are taken for the manufacture of foundation tapes. It is necessary to clear the space under the walls and line the formwork. Other walls at this time rest on temporary supports. It is important to worry about niches for jacks so that later there are no problems with the descent of the structure. After installing the house, the niches are closed with brick – the work is completed.

        Temporary supports

        Temporary supports will ensure the stability of the building during the repair

        As you can see, this process is painstaking and requires an organized approach, however, replacing the foundation with your own hands is quite real, if you approach the work with the mind. A little patience, combined with the knowledge gained, guarantees an excellent result – a new reliable foundation for your wooden country house.