An egg grading hall is a clean room with a wet end

By Johnny Joe, export engineer at Hebei Hongji Shunda Steel Structure Engineering Co., Ltd. · 25 October 2026 · 6 min read

An egg grading line receives eggs from the houses, washes and inspects them, grades by weight and quality, and packs them into cartons and trays.

It is a short process and a simple building, but it contains a boundary that matters: the wet end and the dry end.

The washer is the wettest machine in the plant

Egg washing uses warm water and detergent, and the machine leaks, sprays and drains. The area around it is wet continuously during a shift.

From the washer onwards the product must stay dry: wet cartons fail, and damp packaging is a quality complaint. So the hall changes from a washable wet room at one end to a dry packing room at the other, within a few metres.

A single specification across the whole hall fails one end or the other. The usual answer is a wall or a curtain line at the boundary, with drainage and washdown on the wet side only.

The line is long and straight

Grading machines are configured as a line, and the building has to be long enough to hold it with access on both sides. That makes an egg grading hall a long, narrow building rather than a square one.

The consequence is a large thermal movement along the length, which has to be either jointed or designed for. It is the same issue as any long shed and it is usually solved cheaply if it is noticed early.

Temperature matters more than the structure

Eggs lose quality quickly at high temperature. A grading hall in a hot climate needs to be kept cool, which means an insulated roof and mechanical cooling rather than open ventilation.

That changes the envelope: an insulated roof, closed walls, and doors that are kept shut. The building becomes a cooled box rather than a ventilated shed, and the steel frame behind the insulation has to be detailed so it does not condense.

Trays and cartons are the fire load

Packaging is stored in quantity and it is all paper or plastic. A packaging store inside the grading hall adds a fire load next to a food production area.

A separate compartment, or an external store, is the cheap answer. The same applies to any fuel or chemical store on the site.

The house-to-hall link is the biosecurity question

Eggs move from the production houses to the grading hall. Whether that move is under cover, and whether vehicles or people cross between them, is the main biosecurity decision on the site.

Getting that route right affects the position of the hall more than any structural consideration.

What I want before drawings

• The line length and the machine layout with access requirements.
• Where the wet end finishes and the dry end begins.
• The temperature the hall must be held at, and how.
• The packaging storage volume and whether it is separated.
• The route from the production houses and the vehicle movements.
• The wind speed for the site in km/h from the applicable local code, not a round number.

An egg grading hall is a simple building with one sharp internal boundary. Draw the boundary first and the rest is routine.