You have taken the step to build a house on your property. The basis for this is of course either a stable floor slab or you even want to integrate a cellar. So there needs to be a construction pit.
What needs to be taken into account when digging a construction pit, what regulations there are, Information about duration and costs You can read instructions for a batter board in our article.
1. Without a building permit you are committing a criminal offense
Before you can start planning, digging the pit or building the house, you should take care of regulations and permits. Basically: Anyone who builds without a building permit is violating building law. Unapproved construction measures, also known as “black construction” or, in the case of an excavation pit, “unapproved earth tapping”, are included Fines of up to several hundred euros punished.
A building permit is required a report from a subsoil expert. As soon as the responsible authority gives the green light for the construction project, you can get started.
2. Planning for excavating a construction pit
Construction pit for foundations
If you only want to carry out excavation work for the foundation or floor slab, this is of course a smaller undertaking. A layer of around 20 cm is usually removed for this purpose.
After you have all the necessary permits together, you need to make a detailed plan. The following are important for this:
- the size of the area to be excavated
- the necessary construction machinery and equipment, such as: B. one excavator
- other utensils
2.1. Calculation for excavation
In order to be able to plan costs and scope in advance, It is advisable to determine the construction stroke. For this calculation you simply use the volume formula: length x width x depth = excavated earth. For a small project, for example, this would look like this: 5 mx 5 mx 2 m = 50 m³.
Another factor to consider is a possible slope slope. This must then be deducted from the result of the excavation. With a slope angle of 10%, this would mean for our example: 50 m³ – 10% = 45 m³.
2.2. Length of time
If you hire a construction company, the excavation of the excavation pit should be carried out be done in one or two days. If you want to do the work yourself, how quickly you can progress depends on your equipment and the condition of the ground. On the other hand, we also have to Weather conditions, such as B. Rain that softens the groundbe taken into account.
Of course, the cost factor plays a significant role when deciding whether to dig the excavation pit yourself or commission a construction company to do it for you. We have put together a clear overview for you, what approximate costs you can expect:
|approx. 16 – 20 EUR per m³
|approx. 30 – 40 EUR per m³
|Problematic soils, rocky ground
|approx. 80 – 90 EUR per m³
|approx. 8 – 12 EUR per m³
After digging the excavation pit Of course, the removed ground also has to be disposed of. Many construction companies that dig construction pits also offer this service. You must also take these costs into account when planning.
Good to know: The properties of soils are specified in so-called soil classes. These range from 1 – 7, with class 1 denoting pure topsoil and class 7 denoting rocky subsoil. Most soils in Germany fall into classes 3 to 5, meaning they are medium heavy.
3. 6 tips for digging a construction pit yourself
If you have now decided to dig a construction pit yourself, there are a few things to consider. As with almost every major construction project There are also certain risks associated with digging a construction pit. These include, among others:
- Collapse of the pit walls
- Flooding caused by groundwater and strata water
- Work made more difficult due to soil conditions
This can result in accidents with (personal) injuries. If you dig the excavation pit yourself and have not commissioned a company to do it, you will not have a builder who is liable for the insurance. You bear complete responsibility.
Secure your excavation pit always according to the regulations. In this way you guarantee a successful completion of the construction project as well as the safety of everyone involved.
3.1. Additional costs
If you do not have an idea in advance of the nature of the ground you want to excavate, this can result in tedious additional work. If the ground is difficult, you may have to interrupt or stop your work if you use the wrong equipment, i.e. too ‘easy’.
In this case, the disposal of the excavated material also falls on your shoulders. At a You don’t just have to take care of the transport yourselfbut also expect a price of around 15 EUR per m³.
Danger: “Contaminated” excavation also drives up the price. If there are materials such as roots, building rubble or foreign matter in the soil, you must expect additional charges.
3.2. Important factors when digging a construction pit: batter board and safety distances
The process for digging a construction pit can be roughly divided into 3 phases:
- Setting up the batter board (approx. 3 to 5 hours)
- Excavate (have) the excavation pit
- Laying the underground pipes in the sand bed (approx. 1 hour per linear meter)
A batter board is the basis for building a house, as it measures the exact dimensions. It ensures that both position and height can be implemented as accurately as possible and must comply with the limit distances defined in the building permit. The following procedure is used for this:
- Start by driving three stakes into the ground at a distance of one meter from the corners of the planned building. The depth should be approx. 50 cm.
- Now a mark in the form of a board is made at a height of approx. 50 cm above the planned upper edge of the foundation, with which the pegs are connected. Make sure that the Make sure the boards are horizontal are.
- Repeat this for the other three corners. Make sure the alignment is parallel.
- You can visibly mark out the planned corners of the house using string and nails.
Heavy artillery is now used to dig the excavation pit. An excavator is essential here. For private construction projects Working with a mini excavator is often an option. Read the following about what you need to pay attention to when digging the excavation pit:
- Make sure that the working space within the excavation pit, i.e. the area between the excavation pit wall and the future building, is at least 50 cm.
- There must be a so-called “protective strip” above the excavation pit. This must be at least 60 cm wide.
Image credits: Adobe Stock/Hermann, Adobe Stock/Kzenon, Adobe Stock/Ingo Bartussek, Adobe Stock/WoGi, Adobe Stock/Hoda Bogdan (sorted chronologically or according to the order of the images used in the buying guide)