How to Use a Rotary Laser Level: A Step-by-Step Guide for Site

A rotary laser level is the fastest way to establish a level (or graded) reference across a whole site — far quicker and more accurate than a spirit level and staff on their own. If you're new to rotary lasers, or you've just picked up your first kit, this guide walks through the full process from unpacking to taking a reading.

What you'll need

• A rotary laser level and tripod — for example the Grettz G60 Rotary Laser Kit, which ships with tripod, staff and LR1 receiver in one case.
• A telescopic levelling staff for transferring heights.
• A laser receiver (detector) for outdoor work, where the beam is too faint to see by eye.

Step 1: Set up the tripod on firm ground

Open the tripod legs wide and press the feet firmly into the ground so it can't shift. Aim to get the head roughly level by eye first — it makes the next steps quicker. On soft ground, tread the feet in; a tripod that sinks even a few millimetres mid-job will throw your levels out.

Step 2: Mount the laser and let it self-level

Thread the laser onto the tripod head and switch it on. Any modern self-levelling rotary laser — like the Grettz range — will find level automatically within a few degrees of tilt, usually in under a minute. Wait until the head is spinning steadily and the level indicator has stopped flashing before you take any readings.

Step 3: Set your reference height

Decide on a known point — a datum peg, a damp-proof course, or a finished floor level — and measure the height of the laser plane above it using your staff. This becomes your reference. Every other reading on site is now taken relative to that figure.

Step 4: Take readings with the staff and receiver

Slide the receiver onto the staff, stand the staff on the point you want to check, and move the receiver up or down until it beeps “on grade.” Read the height off the staff. Compare it to your reference to work out whether the point is high or low, and by how much. Indoors, on a bright day you can often skip the receiver and read the beam directly off the staff or wall.

Step 5: Check across the whole area

Because the beam sweeps a full 360°, you can walk the staff to any point within range without moving the laser. This is what makes rotary lasers so quick for setting levels across foundations, patios, drainage runs and floors.

A note on accuracy

Even the best laser drifts over time from knocks and transport. Check your calibration periodically — our guide on how to calibrate your laser level explains a quick field test. Every Grettz laser is also backed by our Service 72 calibration programme.

Which rotary laser is right for you?

For general levelling, the G60 covers most groundworks and site tasks. If you need to set a fall or slope, step up to a dual-grade model like the G70 or the green-beam G80. Browse the full rotary laser range to compare.