Why Fleximake Grain Bunker Covers
- High quality, durable, UV treated Australian made fabrics
- Fully welded seams to ensure waterproofing
- Manufactured using specialised fabric welding machines
- Can supply ground sheets for your grain storage application
- Australia wide delivery
- Robust to withstand to extremes of Australian climate yet they are easy to handle
- Excellent tensile strength to withstand pulling forces on field
- Large sizes can be supplied in one piece to eliminate site joining
- Best Prices in the market
Top Cover Fabric Materials
- Landmark® 340
Landmark® is an environmental alternative to PVC that provides excellent mechanical performance at half the weight of PVC. Landmark® is the product of choice for bulk grain covers, with excellent 'lay flat' characteristics and superior resistance to flex cracking. This fabric comes with 5 year UV warranty
- Landmark® +360
Landmark® +360 is the newest fabric variant in the range, featuring the same great functional benefits as Landmark® 340, with superior tear resistance and tensile performance. It is the most robust polypropylene grain bunker fabric available on the market today. This fabric comes with 5 year UV warranty
- Canvacon® 5000Q0
Canvacon® 5000Q is a premium quality woven polyethylene based coated fabric suitable for smaller grain bunker applications. With a history of over 30 years in the Australian grain market, providing outstanding puncture and abrasion resistance to withstand the harshest of installation and environmental conditions. This fabric comes with 3 year UV warranty
- GrainTuff® 320PE
GrainTuff ® 320PE tarpaulin is an economical heavy duty coated fabric that is especially designed to use as top cover of grain bunkers. This fabric comes with 3 year UV warranty.
- GrainTuff® 610PVC
GrainTuff ® 610PVC is a heavy duty coated reinforced PVC fabric that is especially designed to use as top cover of grain bunkers. This fabric comes with 3 year UV warranty. Service life can be up to 5-years depending on the usage conditions.
Ground Sheet Fabric Materials
- Versatex®
Versatex® is a quality woven polypropylene based coated fabric suited for bunker ground sheet applications.
- GrainTuff® 180PE
GrainTuff ® 180PE tarpaulin is a heavy duty coated fabric that is especially designed to use as ground sheet of grain bunkers.
Dimensions of Grain Bunker
One of the important factor to consider when your designing a grain bunker is the height of the grain bunker. The height of the grain bunker is limited by the stacking height capability of your grain handling equipment. Each grain type will form a heap related to its repose angle. Repose angles for each type grains are as follows
Wheat- Repose angle of 23° from horizontal
Barley, Sorghum, Chickpea, Rice, Soya Bean, Rye- Repose angle of 26° from horizontal
Oats- Repose angle of 30° with respect to horizontal
Barley, Sorghum, Chickpea, Rice, Soya Bean, Rye- Repose angle of 26° from horizontal
Oats- Repose angle of 30° with respect to horizontal
Grain Bunker

Grain Repose Angle

Cross-section of a bunker – Width

Cross-section of a bunker – Length

Following tables provide the dimensions of the top bunker cover required for various grain types and bunker heights to achieve your storage requirement
Top Cover Dimensions for Wheat Bunkers
Repose angle of 23° with respect to horizontal.(750kg per cubic metre)
| Height of side
retaining walls, h(m) |
Bunker
Height H(m) |
Top Cover
Width (m) |
Top Cover Length (m)
|
Length (m)
per 50t |
|||||||||||
| 200t | 300t | 400t | 500t | 600t | 700t | 800t | 900t | 1000t | 1500t | 2000t | 2500t | ||||
| 0.5 | 2.0 | 12.25 | 39.0 | 54.6 | 70.1 | 85.6 | 101.2 | 116.7 | 132.2 | 147.8 | 163.3 | 241.0 | 318.6 | 396.3 | 7.76 |
| 2.5 | 14.75 | 28.5 | 38.1 | 47.1 | 57.3 | 66.9 | 76.5 | 86.1 | 95.7 | 105.3 | 153.3 | 201.3 | 249.3 | 4.80 | |
| 3.0 | 17.50 | 23.7 | 30.2 | 36.8 | 43.3 | 49.9 | 56.4 | 63.0 | 69.5 | 76.1 | 108.8 | 141.5 | 174.3 | 3.27 | |
| 3.5 | 19.75 | 21.4 | 26.2 | 31.0 | 35.7 | 40.5 | 45.2 | 50.0 | 54.7 | 59.5 | 83.3 | 107.1 | 130.9 | 2.37 | |
| 4.0 | 22.50 | 24.1 | 27.7 | 31.4 | 35.0 | 38.6 | 42.2 | 45.8 | 49.4 | 67.5 | 85.6 | 103.7 | 1.80 | ||
| 4.5 | 25.25 | 26.0 | 28.8 | 31.7 | 34.5 | 37.4 | 40.2 | 43.1 | 57.3 | 71.5 | 85.7 | 1.42 | |||
| 5.0 | 27.50 | 29.8 | 32.1 | 34.4 | 36.7 | 38.9 | 50.4 | 61.9 | 73.4 | 1.14 | |||||
| 5.5 | 30.25 | 30.6 | 32.5 | 34.4 | 36.3 | 45.7 | 55.2 | 64.7 | 0.94 | ||||||
| 6.0 | 32.75 | 33.0 | 34.6 | 42.5 | 50.5 | 58.4 | 0.79 | ||||||||
| 1.0 | 2.0 | 12.25 | 54.1 | 76.1 | 98.0 | 120.0 | 142.0 | 163.9 | 185.9 | 207.9 | 229.9 | 339.7 | 449.6 | 559.5 | 10.98 |
| 2.5 | 14.75 | 34.1 | 45.8 | 57.6 | 69.3 | 81.0 | 92.7 | 104.5 | 116.2 | 127.9 | 186.6 | 245.2 | 303.8 | 5.86 | |
| 3.0 | 17.50 | 26.6 | 34.0 | 41.5 | 49.0 | 56.4 | 63.9 | 71.4 | 78.9 | 86.3 | 123.7 | 161.0 | 198.4 | 3.73 | |
| 3.5 | 19.75 | 23.2 | 28.4 | 33.7 | 38.9 | 44.1 | 49.3 | 54.6 | 59.8 | 65.0 | 91.2 | 117.3 | 143.4 | 2.61 | |
| 4.0 | 22.50 | 25.6 | 29.5 | 33.4 | 37.3 | 41.2 | 45.0 | 48.9 | 52.8 | 72.2 | 91.6 | 111.0 | 1.94 | ||
| 4.5 | 25.25 | 27.3 | 30.3 | 33.3 | 36.3 | 39.3 | 42.3 | 45.3 | 60.3 | 75.4 | 90.4 | 1.50 | |||
| 5.0 | 27.50 | 28.5 | 30.9 | 33.3 | 35.7 | 38.1 | 40.5 | 52.5 | 64.5 | 76.5 | 1.20 | ||||
| 5.5 | 30.25 | 31.6 | 33.5 | 35.5 | 37.5 | 47.3 | 57.1 | 66.9 | 0.98 | ||||||
| 6.0 | 30.75 | 33.9 | 35.5 | 43.7 | 51.9 | 60.1 | 0.81 | ||||||||
Top Cover Dimensions for Barley, Sorghum, Chickpea, Rice, Soya Bean or Rye Bunkers
Repose angle of 26° with respect to horizontal.(650kg per cubic metre)
| Height of side retaining walls, h(m) | Bunker Height H(m) | Top Cover Width (m) |
Top Cover Length (m)
|
Length (m) per 50t |
|||||||||||
| 200t | 300t | 400t | 500t | 600t | 700t | 800t | 900t | 1000t | 1500t | 2000t | 2500t | ||||
| 0.5 | 2.0 | 11.25 | 48.8 | 69.5 | 90.2 | 110.9 | 131.6 | 152.2 | 172.9 | 193.6 | 214.3 | 317.7 | 421.1 | 524.6 | 10.34 |
| 2.5 | 13.50 | 34.1 | 46.9 | 59.7 | 72.4 | 85.2 | 98.0 | 110.7 | 126.5 | 136.3 | 200.1 | 264.0 | 327.8 | 6.38 | |
| 3.0 | 15.75 | 27.2 | 35.9 | 44.6 | 53.3 | 62.0 | 70.7 | 79.4 | 88.1 | 96.8 | 140.3 | 183.8 | 227.3 | 4.34 | |
| 3.5 | 17.75 | 23.7 | 30.0 | 36.3 | 42.6 | 48.9 | 55.2 | 61.6 | 67.9 | 74.2 | 105.8 | 137.4 | 169.0 | 3.15 | |
| 4.0 | 20.25 | 21.8 | 26.6 | 31.5 | 36.3 | 41.1 | 45.9 | 50.7 | 55.5 | 60.3 | 84.3 | 108.3 | 132.3 | 2.40 | |
| 4.5 | 22.50 | 24.8 | 28.6 | 32.4 | 36.1 | 39.9 | 43.7 | 47.5 | 51.2 | 70.1 | 89.0 | 107.9 | 1.88 | ||
| 5.0 | 24.75 | 26.7 | 30.0 | 33.0 | 36.0 | 39.1 | 42.1 | 45.2 | 60.4 | 75.7 | 90.9 | 1.52 | |||
| 5.5 | 27.25 | 28.5 | 31.0 | 33.5 | 36.1 | 38.6 | 41.1 | 53.6 | 66.2 | 78.8 | 1.25 | ||||
| 6.0 | 29.50 | 29.8 | 31.9 | 34.1 | 36.2 | 38.3 | 48.8 | 59.3 | 69.9 | 1.05 | |||||
| 1.0 | 2.0 | 11.25 | 69.2 | 99.1 | 128.9 | 158.8 | 188.7 | 218.6 | 248.4 | 278.3 | 309.2 | 457.5 | 606.9 | 756.3 | 14.93 |
| 2.5 | 13.50 | 41.4 | 57.2 | 72.9 | 88.7 | 104.4 | 120.2 | 136.0 | 151.7 | 167.5 | 246.3 | 325.1 | 403.9 | 7.87 | |
| 3.0 | 15.75 | 30.7 | 40.7 | 50.7 | 60.7 | 70.7 | 80.7 | 90.7 | 100.7 | 110.7 | 160.7 | 210.6 | 260.5 | 4.99 | |
| 3.5 | 17.75 | 25.7 | 32.7 | 39.7 | 46.7 | 53.6 | 60.6 | 67.6 | 74.5 | 81.5 | 116.4 | 151.2 | 186.1 | 3.48 | |
| 4.0 | 20.25 | 23.2 | 28.4 | 33.6 | 38.7 | 43.9 | 49.1 | 54.3 | 59.4 | 64.4 | 90.5 | 116.3 | 142.2 | 2.58 | |
| 4.5 | 22.50 | 26.0 | 30.0 | 34.0 | 38.0 | 42.0 | 46.0 | 50.0 | 54.0 | 74.0 | 94.0 | 114.0 | 1.99 | ||
| 5.0 | 24.75 | 28.0 | 31.2 | 34.4 | 37.6 | 40.7 | 43.9 | 47.1 | 63.1 | 79.0 | 95.0 | 1.59 | |||
| 5.5 | 27.25 | 29.0 | 32.1 | 34.7 | 37.3 | 39.9 | 42.5 | 55.5 | 68.6 | 81.6 | 1.30 | ||||
| 6.0 | 29.50 | 30.6 | 32.8 | 35.0 | 37.2 | 39.3 | 50.2 | 61.1 | 72.0 | 1.09 | |||||
Top Cover Dimensions for Oats Bunker
Repose angle of 30° with respect to horizontal.(400kg per cubic metre)
| Height of side retaining walls, h(m) | Bunker Height H(m) | Top Cover Width (m) |
Top Cover Length (m)
|
Length (m) per 50t |
|||||||||||
| 200t | 300t | 400t | 500t | 600t | 700t | 800t | 900t | 1000t | 1500t | 2000t | 2500t | ||||
| 0.5 | 2.0 | 10 | 87.0 | 127.0 | 167.0 | 207.1 | 247.1 | 287.1 | 327.2 | 367.2 | 407.2 | 607.4 | 807.6 | 1007.7 | 20.01 |
| 2.5 | 12 | 57.3 | 81.9 | 106.6 | 131.2 | 155.9 | 180.5 | 205.2 | 229.8 | 254.5 | 377.7 | 501 | 624.2 | 12.32 | |
| 3.0 | 14 | 42.6 | 59.4 | 76.1 | 92.9 | 109.7 | 126.5 | 143.2 | 160 | 176.8 | 260.6 | 344.5 | 428.4 | 8.38 | |
| 3.5 | 16 | 34.5 | 46.7 | 58.8 | 71 | 83.2 | 95.4 | 107.5 | 119.7 | 131.9 | 192.8 | 253.6 | 314.5 | 6.08 | |
| 4.0 | 18 | 29.7 | 39 | 48.2 | 57.4 | 66.7 | 76 | 85.2 | 94.5 | 103.7 | 150 | 196.2 | 242.5 | 4.62 | |
| 4.5 | 20 | 26.9 | 34.2 | 41.4 | 48.7 | 56 | 63.2 | 70.5 | 77.8 | 85.1 | 121.4 | 157.8 | 194.1 | 3.63 | |
| 5.0 | 22 | 25.2 | 31.1 | 36.9 | 42.8 | 48.7 | 54.5 | 60.4 | 66.3 | 72.1 | 101.5 | 130.8 | 160.1 | 2.93 | |
| 5.5 | 24 | 24.3 | 29.1 | 33.9 | 38.8 | 43.6 | 48.4 | 53.3 | 58.1 | 62.9 | 87.1 | 111.3 | 135.5 | 2.41 | |
| 6.0 | 26 | 27.9 | 31.9 | 36 | 40 | 44.1 | 48.2 | 52.2 | 56.3 | 76.5 | 96.8 | 117.1 | 2.02 | ||
| 1.0 | 2.0 | 10 | 128 | 187.5 | 247.1 | 306.7 | 366.3 | 425.9 | 485.4 | 545 | 604.6 | 902.5 | 1200.4 | 1498.3 | 29.79 |
| 2.5 | 12 | 70.9 | 101.8 | 132.7 | 163.6 | 194.5 | 225.4 | 256.3 | 287.1 | 319.0 | 472.5 | 626.9 | 781.4 | 15.44 | |
| 3.0 | 14 | 48.8 | 68.2 | 87.7 | 107.1 | 126.6 | 146 | 165.5 | 184.9 | 204.4 | 301.6 | 398.8 | 496.1 | 9.72 | |
| 3.5 | 16 | 37.9 | 51.4 | 64.9 | 78.5 | 92 | 105.5 | 119 | 132.6 | 146.1 | 213.7 | 281.3 | 349.9 | 6.76 | |
| 4.0 | 18 | 31.8 | 41.9 | 51.9 | 61.9 | 71.9 | 81.9 | 91.9 | 101.9 | 111.9 | 161.9 | 212 | 262 | 5 | |
| 4.5 | 20 | 28.3 | 36.1 | 43.8 | 51.5 | 59.2 | 67 | 74.7 | 82.4 | 90.2 | 128.8 | 167.5 | 206.1 | 3.86 | |
| 5.0 | 22 | 26.2 | 32.4 | 38.6 | 44.7 | 50.9 | 57.1 | 63.2 | 69.4 | 75.5 | 106.4 | 137.2 | 168 | 3.08 | |
| 5.5 | 24 | 25.1 | 30.1 | 35.1 | 40.2 | 45.2 | 50.2 | 55.3 | 60.3 | 65.3 | 90.5 | 115.7 | 140.9 | 2.51 | |
| 6.0 | 26 | 28.7 | 32.9 | 37.1 | 41.2 | 45.4 | 49.6 | 53.8 | 58 | 79 | 99.9 | 120.9 | 2.09 | ||
Fleximake fold your bunker cover in “concertina” fashion prior to roll it on a pipe. This enable you to handle and install the bunker cover easily and quickly.
Tarp folded in Concertina fashion

Tarp rolled on a pipe

Grain Ring Tarps and Ground Sheets

In addition to flat rectangular grain covers, Fleximake also manufactures tarps for grain rings. Grain ring tarps are custom made with conical shape to suit the diameter of your grain ring and the repose angle of the grain you are storing. The tarps are fitted with heavy duty webbing straps for reliable and convenient tie-down.The ground sheets for grain rings are circular shaped to fit perfectly in to your grain ring.
Please contact us with dimensions of the grain ring and type of grain you are planning to store.
Please contact us with dimensions of the grain ring and type of grain you are planning to store.
How to Manage Grain Quality
Managing the grain quality is important to avoid risk of your new season’s grain being rejected by the grain buyer. The quality of grain can be maintained by controlling moisture and pests in storage grain. Protecting the grain from moisture ensures high value of the grain. Low level of moisture in your stored grain helps subduing the growth of bacteria and fungi, and also reduces the breeding of insects and mites. Moisture levels can usually be controlled by loading the grain at low moisture content and controlling insects which create moisture at loading.
















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