After that, the first step in construction activity is site clearance. It was then marking foundation trenches which are going to be excavated. The excavation lines which are marked on site is known as building layout.
How to Building Layout?
- To set out a building after transferring the architectural proposal from drawing into the ground. It establishes location points of the site boundaries, columns, foundation, centre line of wall and other necessary data and level.
- The whole structure will be located due to this initial set out. Accurate set out is the key part of this construction work and errors are very expensive & it needs so much time for correction.
- The structure position and orientation is generally detailed in engineers drawing, and it showed how the layout would be arranged.
- The controlling points of the structure are marked. After that, all the operations will proceed.
Step 1. Temporary Benchmark
- A temporary benchmark is a fixed point with known elevation. It’s the fixed point which starts all level related works.
- After that, a peg or steel angle is placed in that remarked place.
- Temporary benchmark indicated all drawings with levels and vertical dimensions expressed in meters to three decimal places.
Step 2. Baseline
- All the layout task is done is creating a baseline.
- The baseline is a straight reference line is a respect to which the building corners are located.
- Sometimes it coincides with the building line but doesn’t create any problem.
Step 3. Horizontal Controls
- Horizontal control is points which are also known as coordinates with respect to specific issues.
- Control points should be used so that each point of the plan can be located on the ground.
Step 4. Vertical Controls
- The Vertical control points are specified to a vertical datum– often a timber post in concrete.
- These levels are generally established during the levelling phase by using a theodolite.
What Is Method of Layout of Building?
- At first, You need to mark the building layout and tied a line to the corner posts, a nail in the top of the post.
- A theodolite is placed to find out the corners at 90-degree angle after that ranging rod is required to find the straight line between two points.
- Corner posts are usually timber posts which are usually 50 mm x 50 mm set in the ground and marked with a nail at the centre of the centre.
- The outlines are marked by dry lime powder.
- Profile boards are set at a height of 0.6-1 meter.
- When the outline of a building is more complex than a simple rectangle, then it’s necessary to fix up some points.
- Sometimes for the irregular building shape, at first layout a large rectangle which will cover the entire building. Once it will be done deductions, and alternative can be made to obtain the layout.
Some steps are followed for creating the layout of a building. Those steps are-
- Reduced Level Excavation
- Framed Building
Step 1. Trenches
- The layout trenches are done for excavation work. The excavation work is done for excavating the walls, trenches, etc.
- Next, we need to find out a trench position, width, depth. Profile boards should be kept at the 2 m clear from the trench position.
- Pegs are set at the bottom of the trench to mark the top of the concrete strip.
- By using a spirit level, the corners of the wall are transferred from the intersecting line to mortar spots in the foundation.
- When we are cutting trenches, we need to execute the whole work with great care; specially there is a possibility of side caving.
Step 2. Reduced Level Excavation
- The reduced level is set out working from the baseline. Corner posts are fixed outline of the excavation area but marked with sand.
- After controlling the depth of the excavation, sight rails are set.
- After that, the traveller is controlling excavated levels between profiles boards.
- Finally, the height of the traveller has desired to the sight rail level minus the formation level of the excavated area.
Step 3. Framed Building
- The framed building is one of the buildings which are related to the grid. The intersection points of the gridline are marked as the centre point.
- The grid layout is established by theodolite and intersection is marked with pegs.
- Once the grid has set, it’s ready for excavation work.
Control Lines of Construction
Control lines are used for calculating horizontal alignment, vertical alignment and superelevation. Control lines are used for a different purpose in construction.
The types of control lines are
- Vertical Alignment Control Line.
- Horizontal Alignment Control Line.
- Tangent Profile Control Line.
- True Control Line.
- Pegged the Control Line.
Sometimes many control lines are used for the same purpose. Sometimes the control lines have required some guidelines.
Construction layout of the ability of above and below the ground location of structure to be built.
Construction layout provides an accurate, reliable working for planning horizontal dimensions, elevation measurement and similar data.
Construction layout sometimes detects problems before it happens. Construction layout also includes future excavations. Application of construction layout-
- Building Layout
- Curb & Gutter
- Sewer, Water, Storm & Utilities
- Caisson & Column Line Layout
- Final Grading
- Road Work