Bunker Covers
Fleximake grain bunker covers are an affordable method to store and protect your harvest from the elements. Our high quality and high strength grain bunker covers are made from UV stabilized Australian made coated fabric materials. They meet Australian standards and suit harsh Australian weather conditions.
The seams of the grain bunker tarps are fully welded for water-proofing and increased strength. Tough, durable and affordable, Fleximake grain bunker tarps and ground sheets are tear and abrasion resistant with high tensile strength. So don’t take chances with your season’s worth of hard work. Make sure that you have top quality grain bunker covers to protect your harvest!
We manufacture all our grain bunker covers in Australia. We here at Fleximake have the fastest and most sophisticated plastic welding machines in Australia. The modern tech, high speed machines bring us the capability to guarantee you a fast delivery regardless of the size of bunker cover. This also means that we can offer you very competitive prices as opposed to our direct competitors.
Fleximake grain bunker covers are widely used by independent Australian farmers and arge grain dealers in the agricultural sector. We are instrumental in providing temporary but extremely economical storage solutions to manage seasonal supply and demand balance
Fleximake team will work with you to understand your needs and adivse on the best outcome. We make sure that you will be getting grain bunker covers that will perfectly suit your needs.

Why Fleximake Grain Bunker Covers
Top Bunker 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. It has 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
Ground Sheet Fabric Materials
9PP® 145
9PP® 145 is an economical woven polypropylene based coated fabric suited for bunker ground sheet applications.
Versatex®
Versatex® is a quality woven polypropylene based coated fabric suited for bunker ground sheet applications.
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 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 metal pipe. This enable you to handle and install the bunker cover easily and quickly.
Tarp folded in Concertina fashion

Tarp rolled on a metal 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.
Bunker Covers
Philip Burrill from Stored Grain explains how to setup for bunker storage.
Enquire about Bunker Covers
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