An MOT bay has to fit the test class, the building and the equipment. For a Class 4 bay, allow a clear area at least 3.6m wide with 2.4m headroom, rising to 3.8m over the lift, together with the required brake-tester run and headlamp-test area. The layout should be fixed before building work or equipment installation starts.
Design the bay around the class and space
The MOT class determines the basic bay and equipment requirements. The building then determines how those requirements can be arranged: whether a lift or pit fits, where the brake tester and headlamp area sit, and how vehicles enter, move through and leave the bay.
This is why the site survey comes first. Moving a pit, brake-tester recess or equipment run after the slab has been prepared is considerably harder than resolving the layout on the drawing.
Bay dimensions by class
For a Class 4 layout, allow at least 3.6m clear width and 2.4m headroom, rising to 3.8m over the lift. The roller brake tester needs a level area at least 9.0m long by 2.4m wide. The headlamp tester needs a standing area of 3.6m by 2.1m, certified flat within plus or minus 6mm.
Class 7 follows the same basic bay principle but is sized for longer, heavier vans. See the Class 4 and Class 7 bay pages for the complete specification for each class.
Lift bay or pit bay layout
A lift bay uses a four-post or scissor lift on a prepared concrete base. Platforms must be at least 3.9m long with a safe working load of at least 3 tonnes for Class 4, with the lift installed to BS 7980 and fitted with automatic chocks.
A pit bay uses an inspection pit instead of a raised lift. Allow a 3.9m working length, a depth of 1.5m to 1.8m and a width of 760mm to 920mm, increasing to as much as 1.3m for a combined Class 4 and 7 bay. The pit also needs water protection, drainage and a jacking beam.
A raised-floor, pit-free bay is another layout option. Which arrangement fits depends on the building, floor construction and how permanent the installation needs to be.
Concrete, clearances and services
Concrete base
Prepare the lift base to the lift manufacturer’s specification for slab thickness and strength. The installation itself must meet BS 7980.
Clearances
Allow at least 600mm between adjacent equipment and around all parts of the lift, including control boxes, with 1.0m clear ahead of the lift and 1.5m behind the drive-on end.
Services
Confirm the power supply required by the selected lift and test equipment, compressed air where needed, drainage for a pit and an internet connection for the MOT testing service.
Observation
The layout must include a waiting area from which the whole test can be observed directly or by mirror or camera.
The installation process, step by step
1. Site survey
Measure the building, check the floor, access and power supply, and confirm that the selected MOT class can be accommodated.
2. Prepare the pit or lift base
Construct the pit or prepare the concrete base to the required specification. Where concrete or pit work is involved, the programme needs to allow for the building work before the equipment is installed.
3. Install the lift or pit equipment
Install the lift to BS 7980 or fit the pit equipment, including the turning plates and jacking positions required by the layout.
4. Install the test equipment
Position the brake tester, headlamp tester, decelerometer, emissions equipment and play detectors in the surveyed locations.
5. Connect and calibrate
Connect the applicable equipment to the MOT testing service and calibrate it.
6. LOLER examination and handover
Where the bay uses a vehicle lift, complete the LOLER thorough examination and issue the relevant report before handover.
Connecting and calibrating the equipment
For a new bay, the roller brake tester, decelerometer, exhaust gas analyser and diesel smoke meter must connect to the MOT testing service and send readings automatically. These items are calibrated at installation and then kept to the applicable ongoing calibration requirements.
The connection rules are covered in the DVSA approval guide.
MOT bay installation FAQs
How big does an MOT bay need to be?
For a Class 4 layout, allow at least 3.6m clear width with 2.4m headroom, rising to 3.8m over the lift, plus the required space for the brake tester and headlamp-test areas.
Can I have an MOT bay without a pit?
Yes. A four-post or scissor lift, or a raised-floor pit-free layout, are alternatives to an inspection pit.
What concrete does an MOT lift need?
Prepare the base to the lift manufacturer’s specification for slab thickness and strength, with the lift installation meeting BS 7980.
How long does installation take?
There is no single fixed installation time. The programme depends on the building work, particularly whether a pit or new concrete work is required. A site survey is used to establish the work involved.
Does the equipment need connecting?
For a new bay, the brake tester, decelerometer and emissions equipment must connect to the MOT testing service.
Do I need LOLER before testing?
Where the bay uses a vehicle lift, the lift requires a LOLER thorough examination at installation and then at least every 12 months.