Batter board
The batter or the cord Bock used in the building industry for staking and positioning the outer edges of to be erected building and its excavation .
Basics
The batter will be one of the first acts on a construction site of a building to be constructed (after excavation ) by polishing the shell company set up initially as a pure wooden frame so that the cords can be mounted after calibration to the rope goats. The erection of the batter board is one of the contractual ancillary services of the construction site equipment (cost group 390 according to DIN 276). Nevertheless, it is advisable to list this work separately in specifications and thus to remunerate it. In addition, it should also be clarified whether the measurement should be carried out by a surveying office (cost group 700 according to DIN 276) and who has to bear the costs for the official acceptance (cost group 771 according to DIN 276). The cost of creating a lacing system depends on the number of corners of the building and the required cord blocks. If a border distance is to be observed, additional work is required for the investigation of the property boundary in order to maintain the border location.
Instructions for construction work
The positions of the cord blocks are usually about 1 to 2 m outside the later building edges and above the construction pit. This means that these trestles are arranged in such a way that they do not interfere with the construction work or are located at the angle of slope (if this occurs during excavation). For this purpose, three approximately 1.5 m long pointed squared timbers are rammed into the ground in the corner of the building and connected with horizontal boards as rigidly as possible to form triangular frames. Then a plank is fastened diagonally across the corner, which gives the construction the necessary stability of a tripod . According to the building construction theory, the measurement is to be carried out with the lowest dimensional tolerances (± 2.5 mm). So that the batter board cannot change its position after it has been measured, minimum requirements must be placed on the execution. Roof battens as posts (the cross-section should be at least 80 × 80 mm, or 100 mm in the case of halved logs) and thinner cross-battens (material thickness should be at least 28 × 140 mm) are therefore unsuitable. This plank is missing in the photo on the right, the posts are made of roof battens, the cross battens are made of old wood. If the posts are not driven deep enough, the diagonal connections are missing, or if the sections of the trestles are not connected at a corner, the batter board can easily be displaced or accidentally manipulated. Such a batter board does not correspond to the contractual ancillary services for structural work. In particular, the repeated use of used, broken or too thin boards is a violation of the VOB. Alternatively, stable metal constructions are also available on the market that can be used several times. However, these are not protected from manipulation.
Altitude
As a rule, the later elevation of the construction project is now initially measured using the sea level heights (for example by taking over the sea level heights of manhole covers), stipulating the development plan or requesting the building permit with the help of rotating lasers and then determining which height the batter board should represent. The upper edge of the batter boards should make sense to represent the upper edge of the finished floor (OKFFB) of the ground floor. This is particularly recommended on slopes, because it makes the comparison between the OK FFB and the terrain height visible to the layperson. This enables a comparison to be made between the pre / post terrain precursors to be shown in the building application documents in accordance with the building template ordinance in the views and sections. The same also applies to the NN heights of the FFB and terrain heights to be entered in the floor plans NN heights at the building corners.
With the help of the rotating laser, a hose level or a leveling device , the same height is then aimed at all triangular blocks. This can be, for example, the height of the future floor slab, the meter line , i.e. 100 cm above the top edge of the ground floor, for example, or any height coordinate (e.g. 0.5 m to 1.0 m above the ground level ). It is common to use what is known as a stick to align the horizontal boards.
In one implementation (according to the 3D animations), the meter plan with a corresponding plaque can then also be attached to the longer corner posts.
Measurement of the cords
For this measurement, a determination and uncovering of the boundary stones is usually required first and from these points the building position is transferred from the site plan. Since the shell construction company is responsible for the correct transfer of the position, a surveying office should always be called in to measure the corner points.
Then the outer walls are marked out and nails are hammered into these planks so that cords are attached to them that run parallel to the outer walls. By shifting the nails evenly sideways, the building is angled so that all the guide lines actually run parallel to the outer walls. In addition, the building contractor will later attach parallel cords that take account of the recesses in the concrete slab (wall structure / insulation). This should be clearly labeled with comments on the crossbar so that it cannot be confused with the later outer edges of the building.
The last and exact position of the nails should also be marked with luminous paint, otherwise, especially when older boards are used improperly, mix-ups can occur if the nail has to be removed or has been damaged.
This procedure is also the norm when a cellar is to be excavated. Then the crossing points are transferred to the basement foundation and basement floor using a plumb line. Possibly. a second lacing system is also required here.
Decrease
The official batter board approval can also be specified in the building permit. During the batter board acceptance, an employee of the building authority checks the position of the future building on the property, marked by a batter board, as well as the altitude with regard to its compliance with the building permit or other regulations. In principle, the building contractor has to ensure that the specifications from the building permit are correctly adopted, as the building owner usually does not have the necessary measuring equipment. This applies in particular to turnkey construction. If the AN does not request the involvement of a surveying office before the contract is signed, this work is neither to be performed by the AG nor to be paid for.
To this end, a certificate of compliance with the specified area and altitude according to Art. 68 Para. 6 Clause 2 BayBO i. V. m. § 21 sentence 1 PrüfVBau according to Art. 62 Para. 4 BayBO required.
Legal meaning
Even without the official approval, the batter board is of considerable legal importance, because the planned and planned execution of the floor slab is publicly presented in advance, especially in relation to the neighborhood, both in terms of the altitude and in terms of boundary distances. The batter board may only be completely removed when the floor slab has been poured, because then this again represents the points relevant to building law. In addition, due to the attachment in the ground, the batter board, even if it is only a temporary component on the property, is under the sole ownership of the builder / property owner. In this respect, it may not be changed or removed unauthorized and without consultation with the client, because it could also destroy evidence if there were errors in the height, position or dimensions of the floor slab. The unauthorized removal of the batter board can result in criminal and civil law consequences, especially if the evidence for the implementation of the building position or elevation has not yet been achieved by removing other components (floor slab, external masonry). The outer edges of the foundations are often simply concreted into the ground and therefore cannot accurately reflect the position. In this respect, under no circumstances should all cord blocks be completely removed before the floor slab is completed.
Today the setting out is mostly carried out with a total station , especially with larger or more complicated construction sites by a geodesist . During the construction period , the scaffolding must be checked regularly for its stability and correct position.
Examination of the batter board
In a rectangular building, the diagonals between the corners formed by the cords must be the same length. The diagonal of a 90 degree angle is calculated according to the Pythagorean Theorem .
Example: a building with an external length of 6m × 8m is to be erected. According to the Pythagorean theorem (a² + b² = c²) the length of the diagonal is exactly 10 m (6² + 8² = 36 + 64 = 100 = 10²).
Special forms
While the simple batter board only shows the outer edges in a horizontal plane (about 1 m above ground level), in some regions , for example in Switzerland, it is common or even mandatory to use the batter board to display the height of the new building to be erected and on site to visualize ; this will then Baugespann called. For this purpose long poles with triangular connections are attached to the corners of the building. This makes it possible to assess the effect of a building volume in its environment.
literature
- Dietmar Grütze: Building Lexicon. Hanser Verlag, 2007, ISBN 3446404724 , p. 235, article "Schnurgerüst"
