An above-ground granary is an elevated, sealed structure: stand it at least 60 cm off the ground on posts fitted with metal rat guards, leave no gaps larger than 0.5 cm in the walls or floor, and fit screened vents near the top so air crosses the top of the grain mass. One cubic meter holds about 700-800 kg of wheat.
An above-ground granary is a raised, rodent-proof, ventilated building for storing threshed grain through the year.
Height, Seal And Vent Do The Job That A Roof Alone Cannot
The traditional solution across most cultures is an elevated, sealed structure. Height keeps rats out and the floor dry. A tight seal denies mice and insects entry, since rodents can squeeze through incredibly small openings. Vents at the top let moisture escape. Together they keep the grain dry, which is the single most important condition for storing it.
What You Need
- Posts, at least 60 cm high, each with a metal cone or disc (rat guard); salvaged trash can lids work
- Walls and floor with no gaps larger than 0.5 cm: tight board walls on a timber frame, well-sealed wattle and daub, or stone or earthbag, which are rodent-proof by nature
- Screened vents near the top
- A door or hatch at the top for filling and a chute or door at the bottom for emptying
- A site that drains and stays dry
Granary Design and Rat Proofing go deeper on guards, mesh and moisture. Wattle and Daub covers the woven-and-plastered wall.
Method: Build The Granary
Step 1: Set the posts. Place and level the posts at least 60 cm above ground. Fit a rat guard on each, tight to the post with no gaps.
Step 2: Frame and floor. Build the floor and frame so that no gap exceeds 0.5 cm. Check every joint.
Step 3: Wall it. Use tight board walls, sealed wattle and daub, stone or earthbag.
Step 4: Add vents. Fit screened vents near the top. Air must flow across the top of the grain mass, not through it.
Step 5: Fit the doors. A door or hatch at the top for loading, and a chute or door at the bottom for emptying.
Step 6: Clear the surroundings. Keep the ground around and under the granary bare and free of rubbish.
Worked Example
A family of 4 needs 200 kg of grain per person per year, 4 × 200 = 800 kg. At 700-800 kg of wheat per cubic meter, that fills 800 / 800 = 1.0 m³ up to 800 / 700 = 1.14 m³. Add 50% for crop failure: 800 × 1.5 = 1,200 kg, which fills 1,200 / 800 = 1.5 m³ up to 1,200 / 700 = 1.71 m³.
Common Mistakes
- Posts too low — rats jump; see Rat Proofing for the climbing and jumping reach.
- A single big gap or knot-hole — one gap is enough.
- Vents with no screen — insects, birds and rodents enter.
- Grain stored damp — no granary will save it; dry it first.
Safety
Grain engulfment and dust
Flowing grain acts like a liquid. A person who walks on stored grain, or stands over an unloading chute, can be pulled under within seconds, and nobody can pull them free by hand against the load. Never walk on grain; never enter a deep grain store alone; if entry is unavoidable, use a second person outside, a harness and line, and rescue from above with the line, never by going in after them. Stop the unloading chute before anyone enters. Grain dust in an enclosed space can also explode if an open flame or spark reaches it, so keep lamps and fires away from a granary.
What’s Next
- Learn next: Moisture & Pest Control — keeping the grain dry and clean
- Combine with: Capacity Planning — sizing the store