Flat foundations are the cheapest thing you can do right on a construction site – every centimeter that is “lost” here is later made up for with expensive material in the floor. With a rotating laser, one person can handle the heights of the entire construction site. Here's how.
What you will need
- rotating laser with external receiver,
- tripod with 5/8″ thread,
- a telescopic staff with a millimeter scale (for example 5 m),
- elevation point – the ±0.000 mark from a surveyor or a fixed point from which everything depends.
Step 1: Place the laser outside the work area
Place the tripod on a firm, flat surface so that it will not interfere with your work – ideally outside the excavation, in a place where the beam can “see” all corners of the structure. Press the tripod legs into the ground. Screw the laser in and turn it on.
Step 2: Wait for self-leveling
The laser levels itself to a horizontal plane if the tripod is approximately level (within ± 5°). It flashes while it is leveling; when the head rotates, it is ready. If someone moves the tripod while working, the laser stops and warns you (HI-alert function) - then the measurements must be repeated.
Step 3: Set the receiver to the elevation point
Place the staff at the height point ±0.000. Move the receiver along the staff until it starts to emit a continuous tone – this is exactly the plane of the laser. Lock the receiver on the staff and read the value on the scale , for example 1,420 mm. This is your reference.
Step 4: Calculate the target value
If the top edge of the foundations is to have a height of, for example, –0.150 m (15 cm below ±0.000), you must read 150 mm more on the batten at the correct height:
1,420mm + 150mm = 1,570mm
Therefore, move the receiver to 1,570 mm and lock it in place. From now on, a simple rule applies: where the receiver beeps continuously, that is the correct height.
Step 5: Check the corners and formwork
Walk the batten around the corners and along the formwork:
- rapid beeping – you are above the plane, you need to slow down,
- slow beeping – you are below the plane, it should be added,
- continuous tone – the pitch is right.
When pouring concrete, mark the height on the formwork with a nail or paint and pull the concrete to the marks.
Practical tips
- Set the rotation to the highest speed - the reaction is fastest when working with the receiver.
- Use the receiver's fine mode (± 1 mm) for final inspection, coarse mode (± 2 mm) for quick plane search.
- For longer distances, a digital receiver is worth using, as it shows the deviation directly in millimeters.
- Do not move the laser between measurements. If necessary, re-reference the height point.
Do you need advice on a specific project? Give us a call - we'll be happy to help with laser setup.