Shelf width is set by how far a picker can comfortably reach; tier count is set by ceiling height, airflow, and whether you have access equipment that makes the top tier as easy to pick as the bottom one. Growing area and marketable yield are not the same number. Past a certain density, picking slows and selection quality falls faster than the extra square metres add, so the theoretical yield of the room stops arriving in the cold store.
How wide should a mushroom shelf be?
Commercial mushroom shelves generally run between 1.2 and 1.4 metres wide. Inside that band the decision is ergonomic rather than structural: a picker has to reach the centre of the bed from one side, and once that reach becomes a stretch, people brace themselves against the rack. That is where fatigue and back injuries come from — and it is also where selection quality drops, because a mushroom that is awkward to reach gets a shorter look than one in front of you.
1.34 metres is a common working width where picking is done from a trolley that holds the operator at a set distance from the bed. It keeps most of the surface inside an easy arm’s reach while giving up very little growing area.
How many tiers can you realistically pick?
Five to seven tiers is the usual range. Ceiling height sets the maximum; ergonomics decides where inside that range you actually land.
| Consideration | Effect of adding tiers | What has to be in place |
|---|---|---|
| Top-tier access | hardest level to pick, and the one that gets rushed | powered lift on the picking lorry |
| Bottom-tier access | crouching and kneeling for long periods | platform that lowers to a working height |
| Clear gap between tiers | below about 60 cm the back of the bed goes dark | slim profiles and in-row lighting |
| Airflow and CO2 | heat and CO2 collect between close-set beds | slim profiles, verified air distribution |
| Load per tier | more weight carried by each upright | shelving rated for your compost depth |
| Watering uniformity | top levels are hardest to water by hand | automated or fixed watering, not a hose |
What does tier count do to the microclimate?
More tiers means more bed surface in the same volume of air, and the middle levels feel it first: heat and carbon dioxide collect between beds that sit close together, and the crop there is the last to be noticed when it underperforms. A slimmer aluminium profile blocks less of the cross-section than a steel or timber beam of the same capacity, so air moves more freely between the tiers. That is part of why aluminium shelving tolerates a seven-tier layout better than heavier constructions of equivalent load rating.
What access equipment does a high-density layout need?
Above five or six tiers, powered access stops being an upgrade and becomes a condition of the layout working at all. The NEWTON picking lorry raises the operator electrically to the upper levels and lowers to a working height for the bottom ones, so the sixth tier is picked with the same care as the first. The PASCAL picking trolley covers lower-density rooms, holding the operator at a fixed comfortable distance from the bed.
Without powered movement, the labour cost of a dense room absorbs the extra yield. Kilograms per hour falls, staff fatigue rises, and turnover follows — which is the expensive part, because an experienced selective picker takes months to replace.
How do you actually decide?
- Measure the ceiling, then subtract. Take off the clearance the top tier needs for lighting and access. What is left is the tier count you can pick, not the one that fits.
- Fix the width to reach, not to area. Stay inside the 1.2–1.4 m band and test the chosen width with your own team before ordering.
- Check the gap, not just the count. A tier you cannot see into does not produce grade-A mushrooms, whatever the plan says it grows.
- Match the equipment to the density before you commit. Choosing the layout first and the access equipment afterwards is how rooms end up with a top tier nobody picks properly.
Related reading
- Rack design, light and visibility
- Shelf load rating and compost depth
- Aisle widths and worker safety
- Knowledge hub
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