Grain store design: nine things to decide before you ask for a price

Two farmers can ask for "a 1,000-tonne grain store" and get prices that are miles apart, because they've described two different buildings. Deciding these nine things first will get you prices you can actually compare, and a store that works.

1. Tonnage and crop

Start with how much you need to store at peak, and which crops. Different grains have different bulk densities, so the same tonnage of wheat, barley, oats or oilseed rape takes up different volumes. Allow for growth and for years with a big harvest.

2. Storage depth against the walls

How deep you store against the walls is the biggest single design decision. Deeper storage means a smaller footprint, but higher loads on the walls and frame. Your store's walls and frame must be designed for the actual grain depth you'll use. Don't store deeper than the design allows.

3. Push walls

Grain-retaining walls take a lot of sideways pressure. The common options are:

• Precast concrete panels, slotted between the steel columns
• Steel-framed panels designed for grain loads
• In-situ reinforced concrete walls

Each has different costs, lead times and durability. The steel frame must be designed with the wall loads included. A standard shed with walls added later is a common cause of problems.

4. Drying

Decide how grain will be dried and conditioned:

• On-floor drying, with ventilated floors, underfloor ducts or above-floor laterals and fans
• A continuous-flow or batch dryer feeding the store
• Conditioning fans to cool and hold grain once it's in store

On-floor drying affects the slab design, so it has to be decided before groundworks.

5. Ventilation and condensation

Grain gives off moisture and heat. Without enough ventilation, condensation can form under the roof and drip onto the crop. Ridge ventilation, roof sheeting with anti-condensation lining, and open or louvred gables all help. In Scotland's climate, this matters.

6. Doors, loading and lorries

Measure the machines that'll use the store:

• Tipping trailers need height when tipping, not just when driving in
• Loading shovels and telehandlers need turning space and reach
• Grain lorries need a turning circle and hard standing outside

Door width and height, and whether you need doors on more than one side, change the frame design.

7. Floor slab and yard

The slab must carry the grain, the machinery and any drying system. It also needs to be smooth for loading and easy to clean. Think about the apron outside too: lorry access, drainage and where water runs.

8. Vermin and birds

Grain attracts birds and rodents. Bird mesh on open areas, well-sealed cladding, good door seals and a tidy perimeter help. Many grain assurance schemes have requirements on pest control, so check yours.

9. Future flexibility

Will you ever want part of the store for machinery, fertiliser or straw? Putting in bay divisions, extra doors or a slightly bigger footprint now is usually cheaper than adapting later.

Planning and warrants

A new grain store may be able to use Class 18 permitted development after prior notification, if it's within the limits, including 1,000m² ground area and 12m height. Many grain stores are over 280m², so they're likely to need a building warrant. Read do farm buildings need a building warrant?.

What to send for a price

• Farm postcode and the proposed site
• Peak tonnage and crops
• Storage depth you'd like
• Drying method
• Machines that'll use it, and door positions
• Any future uses

With that, we can give you a budget figure for the whole building: groundworks, frame, push walls, envelope, doors and services. See grain stores. Guide price: [PRICE: Iain to confirm]

FAQs

How do I work out the size of grain store I need?

Start with your peak tonnage and crops, then decide how deep you'll store against the walls. Those together set the floor area.

What are push walls in a grain store?

Walls designed to hold the sideways pressure of stored grain, usually precast concrete, steel panels or reinforced concrete.

Can I add push walls to an existing shed?

Only if an engineer confirms the frame can take the loads. Many existing sheds weren't designed for it.

Does on-floor drying affect the slab?

Yes. Ducts or laterals and fan positions need to be designed into the slab before it's poured.

How do I stop condensation in a grain store?

Good ventilation, such as ridge vents, and roof sheeting with an anti-condensation lining.

Send your tonnage for a price

Tell us your tonnage, crops and how you load and unload.

Send your tonnage