After obtaining a building permit, the development of the building plot is commenced both for the construction period, and for a permanent period in accordance with the construction design approved by the building authorities. Then the positioning is made (stakeout) building (buildings) in the field.
Staking out is an appointment in the plan (on the premises) outline of the designed building, and then consolidate the main points in a way, which would allow their exact location and verification during construction. For this purpose, wire benches are used, which are placed next to the trenches. The benches must be strong, so that they do not suffer deformations during the execution of works.
Building stakeout - wire benches: a) plan of the basement of the building with sections after digging the excavations, b) axionometric drawing of the trench part with stretched wires and a plumb, c) detail of the bench and excavation.
After the building has been marked out and before the excavations are started, the top layer of arable land is first collected and transported to be used for cultivation.
Depending on the dimensions in the plan, the following types of excavation are distinguished:
a) narrow-space excavations with a bottom width equal to or less than 1,5 m and a length greater than 1,5 m,
b) cavernous excavations (spotlights) with the width and length of the bottom or a diameter of not more than 1,5 m,
c) wide-area excavations with bottom dimensions corresponding to a significant part or all of the building's horizontal projection.
The angle of inclination of the trench walls can be taken in the soil:
- rocky 90 °
- clayey 60-75 °
- clayey 70-80 °
- sandy 45-55 °
- vegetable up to 45 °
The width of the trench horizontally at the bottom of the footing or footing should be greater than the footing width (feet) The 5-10 cm from the outside, so that the formwork can be set up.
After wide-area excavations are completed, narrow-space excavations are made for footings and foundation footings. These excavations, as well as the final horizontal and vertical adjustment of the excavations, are performed by workers with shovels. If the ground is hard, e.g.. compact clay, and the bench is to be concrete, the trench is made with vertical walls as wide as a bench. Then formwork is not used, and the bench can be concreted directly in the ground.
Trench wall in rocky or compact soil; 1 - concrete bench, 2 - formwork, 3 - wooden bowstring.
If waterproofing is provided from the outside, e.g.. heavy type, the trench wall should be made at a distance of approx. 50-80 cm from the basement wall, to allow access to the performance of insulation works.