Short answer
Every module stands on levelling castors. Level the run with the adjusters before bolting the modules together, work from the highest point of the deck, and accept that castors take up millimetres rather than gradients.
Work from the high point
Find the highest point of the deck, set the first module there and level it. Every other module is adjusted up or down relative to it.
If you start anywhere else, you will run out of adjuster travel at the high end and have to lift the whole run.
Level, then bolt
Level each module individually, then bolt them together, then check the line again. Bolting can pull a module out of level, and a run bolted first is much harder to correct.
Bolt through the side panels, not the front. Nothing structural is carried by a door.
What castors can and cannot do
They take up a few millimetres of unevenness across a run, which is what a deck actually gives you. They do not fix a slope.
More than about 2% fall and the run will visibly step, and no amount of adjustment will hide it. Build a base instead.
When to stop levelling and build a base
On gravel, which will settle differently under each module. On a deck with flexible boards, where the module sinks and the joint opens. On any surface with a slope.
A treated timber base or a paved kerb takes an afternoon and solves the problem permanently. Fighting it with castor adjustment costs more in time and never quite works.
The order that avoids a visible step
Bolt the run together first
Levelling module by module and then bolting produces a step at every joint. The run is levelled as one object.
Level the front line, then the back
A spirit level along the front face sets the line a visitor sees. The back only has to stop the run rocking.
Adjust at the castor, not with packers
Stainless packers under a castor trap water. The castor thread has 30 mm of adjustment, which is enough on any sensible slab.
Brake all four castors at the end
Two braked castors is a run that pivots. All four is a run that stays where it was levelled.
Set the counter last
The top is what shows any error in the frame. Setting it after the run is level and braked is the difference between a straight joint and a shim.
Questions we get about this
Do the castors lock?
Yes, every castor has a brake. Lock all four before opening a lid or using the counter — this matters most on the grill module.
Do I need to fix the run to the wall?
No, and we would rather you did not. The modules bolt to each other and stand on their own castors. Fixing to a wall transfers wall movement into the cabinet line.
How many people to assemble a run?
Two. The modules are manageable but awkward, and the counter needs two to set down without twisting it.
Before you order anything
Send the grill model and the run length. You get the aperture, the module list and one itemised price back in writing — freight shown separately, valid 15 days.