Gravy for columns sp. Manual for SNiP 2.09.03-85

How to lay a foundation for an old wooden house without special construction equipment

Old wooden houses were built on tarred logs.
There are no such buildings in the south of Russia, but in the areas north of the Voronezh region, where vast forests begin, wood is the main building material. Nowadays residential buildings are built on concrete foundations. Such a foundation collapses over time, and the log house begins to settle on one side. In this case, the rotten parts should be replaced with modern building materials. Before starting work, you should find out how to lay the foundation under an old wooden house without lifting the building with a crane.

Reasons for replacing the foundation

Beds lying in the ground deteriorate over time under the influence of dampness. Freezing in winter, in spring they thaw, swell and begin to crack and rot. After several decades, in such conditions, the logs become completely unusable. There are several reasons for the destruction of the old foundation under the house:

too much load;
errors in calculations for bed depth;
the foundation under the building has rotted from age.
unsuccessful reconstruction, which led to an increase in the weight of the structure;
improper foundation laying;
freezing of the soil, which caused cracking of logs.

Restoration of the foundation under a wooden house must be carried out immediately after defects have been discovered. Rotting of the beds leads to destruction of the base. After this, the structure begins to settle to one side. Failure to distribute the weight of a building causes it to collapse. Living in a dilapidated house is unsafe.

Types of foundations for replacement

The old foundation under a wooden house is destroyed under the influence of high humidity and climatic conditions. Homeowners believe that it is not possible to replace rotten beams without dismantling the roof and walls of the log house. Rolling a house over a log in order to replace parts lying at the base of the structure is not economically profitable and takes a long time. It is not necessary to carry out complete dismantling for this; there are reconstruction methods that allow repair work to be carried out without the involvement of construction crews and special equipment.

There are several ways to pour a foundation for a finished wooden house:

Strip foundation - laid out with ready-made concrete blocks or poured under the walls of the building. Such a foundation evenly distributes the weight of the house and can be built on soil of any density.
The columnar structure is suitable when the house has small dimensions and weight.

This base is easy to build. The base is installed on pillars driven vertically into the soil. The strength of the structure is ensured by special concrete beams.

Pile foundations are used on uneven terrain and close proximity to groundwater.

The length and cross-section of the pile can be any.

Monolithic slab - placed under the house when it is built on swampy soil.

The formwork is installed around the perimeter of the building, and the entire area under the house is poured. The result is a secure foundation. This type of foundation is more expensive than others.

Monolithic bases can be mounted from ready-made iron-concrete slabs. Several reinforced concrete products are pushed from different sides one by one. The joining place is filled with concrete solution.

After examining the old foundation, it became clear that it urgently needed to be reconstructed. It remains to figure out how to add a foundation to an old wooden house without raising the house. Actions begin with determining the appropriate type of base.

This is done before dismantling the rotten logs and lifting the wooden house onto the foundation, since in each case different technology is used.

Add a finished foundation

Question:

Construction. I poured the foundation for the house, and now I need to pour more concrete under this foundation, how to do this correctly?

Alexander, Blagoveshchensk.

Answer:

Hello, Alexander from Blagoveshchensk!

It was necessary to immediately pour it to the required calculated depth. And now this is resulting in a very big hassle - a problem.

If I understand correctly, then it is necessary to pour under the foundation, and not from the side along the entire perimeter to increase the thickness of the old foundation, while simultaneously increasing its depth. Although such options are also practiced. That is, along the entire perimeter, but not continuously, but in sections (about 1.5 meters long), they dig a trench of the required depth, for example to a depth exceeding the depth of soil freezing at your latitude. They make a sand bedding-cushion about 10 centimeters thick for the new foundation.

The width of the trench is usually from 30 to 40 centimeters. If it’s less, then you’ll have a hard time digging, and if it’s more, then a sea of material will go there.

Everything is done with great precautions, since the soil, especially if it is sandy, can crumble. At a depth of about one and a half meters, this is fraught with consequences. Sometimes you have to make formwork.

To ensure maximum adhesion between the new poured foundation and the old one, scraps of reinforcement are driven into the latter using a hammer drill and a sledgehammer. It is a good idea to attach a welded mesh to them. Then there will be a certain guarantee that the foundation, both old and new, will be one.

The new foundation is poured into the excavated sections of the trench. After it hardens, they dig a trench between these areas. And everyone repeats.

It’s difficult and time-consuming, but how could it be otherwise?

As a result, you get a solid and single base of the building, twice as thick as the original one, but also narrower to the required depth.

The second option - everything is done exactly the same as the first time, but the previous shallow foundation is dug to the required depth. And also in sections, about one and a half meters long. Why not more, I think, there is no need to explain, it might collapse.

Concrete is poured only under the old foundation. Portable panels made from edged boards or scraps of thick plywood are used as formwork. They are secured with stakes (reinforcement) driven into the ground and propped apart with bars, one side resting against the shield, the other against the wall of the trench.

The upper part of the shield should have a slot for throwing concrete through it with shovels. In this case, it is best to pour concrete with a mixer, but this, of course, is not always possible.

In the second case, no reinforcement is needed. But all this is provided that your original foundation was poured with a strip. If it is built simply from rubble stone, and even with a poor binder, then everything must be done doubly carefully.

Twice I witnessed how collapsed earth covered people who were performing similar operations. Therefore, formwork made of boards and its reliable fastening are first of all. Life is more valuable.

I don’t know how satisfied you are with my answer, maybe someone will advise something else. We did as he told us several times, everything worked out.

Good luck!