A shrimp line is a floor problem before it is a building
Shrimp and fish processing is a wet business from the moment the product arrives. There is water on the floor in the receiving area, water in the peeling and grading area, ice in the packing area, and a hose in somebody's hand most of the shift.
The building that houses it is usually discussed in terms of span and height. The part that decides how the plant feels in year five is the floor and what happens at the base of every column standing in it.
The floor is a machine, not a surface
A wet processing floor has to do four things: fall to the drains continuously, resist the water and the cleaning chemicals, survive being hit by bins and pallet trucks, and provide a surface people can stand on for a shift without slipping.
Those four requirements interact. A hard, smooth, chemically resistant floor is often a slippery one; a profiled anti-slip floor is harder to clean. The resolution is usually a surface that is textured enough to grip and detailed so that it can be washed, which is a decision better taken with the people who will clean it.
The fall has to be continuous all the way to the gully
Water does not fall to a nominal slope. It falls to the low point, and if the low point is not the gully, the water goes where the slab actually is.
The common failure is a floor designed to fall one way and then changed — a wall moved, a line relocated — without re-checking the falls. The result is a puddle in a corner, and that corner is almost always at a column base.
The column base is the detail that decides the building's life
A steel column in a wet room stands on a baseplate, on a plinth, or directly on the slab. The choice is not cosmetic.
If the baseplate sits at floor level in a room that is washed daily, water stands on it. The plate, the anchor bolts and the bottom 200 mm of the column live in a puddle for the life of the building. Raising the base on a concrete plinth — with the floor falling away from it — costs a small amount at construction and buys the whole bottom of the structure.
Gullies, kerbs and where the water is allowed to go
Gullies should be numerous enough that nobody has to move a puddle twice, and positioned where the equipment stands rather than on a regular grid. Kerbs should keep water in the wet zone and out of the dry one, and the dry zone should be a real place, not a strip along the wall.
Where the process crosses between wet and dry, the boundary is a wall or a level change. Water running downhill into a dry store is not a cleaning problem; it is a building problem.
The roof does the same thing in reverse
A warm, humid room under a single-skin metal roof will condense on the underside of the sheet and drip. That drip lands on product, on people and on equipment.
The answers are the same as in any wet food room: a liner panel that keeps the water off the product but adds weight to the purlins, a membrane that absorbs and re-releases it, or ventilation that keeps the underside above dew point. All three are building decisions, and all three are cheaper before the roof is ordered.
What I want before drawings
- The layout with the equipment positions, because the gullies follow the equipment.
- Where water is used, and how much, and with what chemicals.
- The wet and dry zones, and what separates them.
- Whether the baseplates will be at floor level or on plinths, decided now.
- Whether bins and pallet trucks will hit the columns.
- The wind speed for the site in km/h from the local code, not a round number.
In a wet plant, the structure survives or fails at the floor line. Everything above it is easier to fix.
Written by Johnny Joe, who advises owners and project managers in Africa and South America on steel buildings. If this decision is live on a project, send the layout and the constraint that worries you and I will tell you what it changes.
Related: a wet building with a dry end · corrosion class as a selection input · raised dock or level entry · the hardest envelope in food processing
