Clear height is the figure every density calculation starts from, and it is also the one that most often arrives measured wrong. The number a client brings is almost always the ridge height, which in a gabled building can sit several metres above the height that can actually be used. This page explains what exactly gets measured, with what instrument, at how many points, at which stage of the project, and what happens when the resulting value falls below what a given system asks for. That last part is the important one.
What clear height is and what it is not
Clear height is the vertical distance between the finished floor and the lowest thing hanging from the roof in that area. The lowest thing is almost never the structure: usually it is a sprinkler pipe, a cable tray, a ventilation duct or a suspended light fitting. Nor is it the ridge height, which is the highest point of the roof, or the eaves height, where the roof meets the wall. In a gabled building the ridge can sit several metres above the eaves, and equipment does not work at the ridge: it works along an entire aisle, so the governing height is the lowest one along that run. Confusing these numbers is the most common and most expensive error, because the whole proposal is sized on top of it.
How it is measured and at how many points
It is measured with a laser distance meter resting on the finished floor, not on a pallet or a platform. And it is not measured at one point: a grid is taken covering the entire usable area, with extra points under every suspended element. In a gabled building it is measured along the column line and at the centre of the span, because those are the two ends of the range. The value that enters the calculation is the minimum across the area where equipment will operate, not the average. The position of each obstruction is recorded too, because a pipe crossing the whole building is not the same as a single light fitting: the first lowers the height of an entire sector, the second can often be relocated. This measurement happens during the survey visit, before anything is sized.
What to do with localised obstructions
A localised obstruction is an isolated element that lowers clear height in one spot and nowhere else: a light fitting, a fan, a short run of cable tray. For those there are three routes, evaluated in that order. The first is to relocate the element, which is usually cheap compared with losing a level of height across the whole warehouse. The second is to design around it: leave that position unused or lower only that module, which costs capacity but no construction work. The third is to accept the reduced height as the project value, when the obstruction is continuous or when moving it means touching the fire protection system, which is a project in itself. What is never done is measuring at the highest point and hoping it sorts itself out on site.
From clear height to capacity: how it translates
Once clear height is measured, the next step is translating it into capacity. Using the height can multiply what you store today with conventional racking by up to 3 times, and that is the ceiling. How much of that margin you reach is not estimated from height alone: it comes out of the layout, the load unit and the real turnover of the catalogue, which is what decides how many levels fit and with what access. It is a design estimate, not a contractual promise. As an equipment reference, automated pallet systems work in a range of 7 to 40 metres. That range describes how far the equipment reaches, not a threshold you must clear to become a client. It tells you which alternatives to look at.
What if I have less height than a pallet system asks for?
It is not that you fail to qualify. It is that the answer is a different one, and there is usually more than one. If the constraint is height and the volume is cases or single units, vertical storage towers use the available height without needing the metres a pallet system asks for, and they bring goods to the operator instead of sending the operator to find them. If the volume is pallets, the usual route is high density at lower height: compact systems where pallets are stored in depth rather than in height. And if what you are losing is floor area to oversized aisles or to slotting without criteria, the biggest gain comes from reorganising the layout, which requires no height at all. In many warehouses that third option pays best, and it is the first one evaluated.
Why height is worth money
Value space using your own rent or property opportunity cost. Released space can support growth or reorganization; it only saves rent when an actual payment obligation is reduced.
What to take away
Clear height runs from the finished floor to the lowest thing hanging from the roof, it is measured at several points with a laser, and the value that counts is the minimum along the run, not the average and not the ridge. From there comes the densification factor and with it the estimated capacity. And if the number falls short of what a pallet system asks for, that closes no doors: it changes the list of alternatives. Vertical towers, high density at lower height, or simply a better resolved layout all stay on the table.
Frequently asked questions
No. Clear height is measured from the finished floor to the lowest thing hanging from the roof in that area, usually a sprinkler pipe, a cable tray or a light fitting. Height to the roof, or to the ridge, ignores all of that. In a gabled building the gap between the two can be several metres, and sizing with the wrong number invalidates the entire proposal.
Never just one. A grid is taken covering the usable area, with extra points under every suspended element, and in gabled buildings measurements are taken both along the column line and at the centre of the span. The value entering the calculation is the minimum across the area where equipment will operate, not the average, because equipment travels whole aisles and has to clear the lowest point.
Up to 3 times what you store today with conventional racking, which is the ceiling. There is no per-band figure we can publish: final capacity depends on the layout, the load unit and the real turnover of your catalogue, and it comes out of the survey with your own data.
Then an automated pallet system, which works in a range of 7 to 40 metres, is probably not the route, and that is all it means: one option ruled out among several, not a rejection. Vertical storage towers remain available for cases and single units, as do compact high-density systems that store in depth, and layout reorganisation, which frequently pays best of all.
Sometimes, and more cheaply than expected. Relocating light fittings, fans or short runs of cable tray can recover tens of centimetres across a whole sector. Moving the fire protection system, by contrast, is a project in itself and has to be assessed as one. The decision comes from comparing the cost of that move against the level of height gained across the entire area.