Open-top containers · Replacement covers · Custom supply
A container tarp should fit the roof profile, clear the corners and align with the fastening points. DERFLEX supplies PVC coated polyester materials and custom shipping container cover options for open-top cargo, container yards and replacement programs.
Specify finished dimensions, fabric weight, reinforcement, seam construction and hardware together. Start with your container drawing or an existing cover sample; then confirm the details needed for a repeatable fit.
20 ft, 40 ft and custom configurations • Sample and drawing review • Bulk and OEM enquiries
A direct answer
A container tarp is a flexible cover fitted over an open-top container or exposed containerized cargo to reduce rain, dust and outdoor exposure. A shipping container cover commonly uses coated fabric, reinforced edges and eyelets or other attachments matched to the container. Its performance depends on the installed cover assembly, including seams, support, fit and drainage.
For container operators, repair depots and leasing fleets. Capture corner reliefs, eyelet positions, door-header details and roof-bow contact points.
Useful starting point: a labelled container model, dimensioned drawing and photos of the old cover fitted in place.
For stationary outdoor storage. Specify the supported roof profile, protected opening, installation route and how the cover stays clear of doors and ventilation.
Useful starting point: storage duration, weather exposure and a drawing of the support and attachment arrangement.
For irregular machinery or tall cargo. Measure the cargo envelope and identify sharp edges, protective pads and cover tie-down paths.
Use the freight tarp guide for additional open-deck cargo-cover considerations.
First, establish the fit
There is no universal finished tarp size for every 20 ft or 40 ft container. Measure the cover path over the actual supports, then define edge overlap, corner clearances and attachment positions. A roof-opening dimension, nominal container length and finished tarp dimension describe different things.
Carrier examples list roof openings of 5,338 × 2,230 mm for a 20 ft open top and 11,552 × 2,230 mm for a 40 ft open top. These are opening measurements, not ordering sizes for covers. Hapag-Lloyd notes that container dimensions vary by manufacturer.[1]
| Drawing item | Record this | Mismatch to prevent |
|---|---|---|
| Overall finished size | Length, width and the agreed measuring condition; label front, rear, left and right. | A cover that reaches the opening but misses the attachment line. |
| Supported profile | Roof-bow shape and positions, raised cargo and contact zones. | Insufficient material over a raised profile, or unsupported fabric collecting water. |
| Corner and end geometry | Reliefs, flaps, drops and door-header interface. | Bunched corners, exposed gaps or interference with operating hardware. |
| Attachment layout | Centre positions, opening size, reinforcing patches and cable route. | Eyelets that cannot align with the existing bars or rings. |
| Repeat-order identity | Drawing revision, approved sample reference and front/rear labels. | Different container models receiving the same replacement cover. |
Material weight is one decision
DERFLEX has published 650 gsm and 900 gsm PVC container-cover material references with 1000D × 1000D polyester base-fabric options. Start with the required handling, abrasion and exposure conditions, then confirm the grade and reinforcement. GSM is mass per area; it is not a wind rating, service-life guarantee or finished-cover strength result.
| Decision | Available direction / requirement | What to compare before ordering |
|---|---|---|
| Fabric body | PVC coated polyester; knife-coated and other coated constructions are published by DERFLEX. | Base fabric, coating build, flexibility and weld compatibility. See PVC tarpaulin material options. |
| 650 gsm direction | Lower material mass than a 900 gsm panel of equal area. | Assess the approved grade where repeated folding and handling weight are priorities; verify performance for the actual duty. |
| 900 gsm direction | Higher material mass for the same panel area. | Evaluate for demanding contact and repeated use when the selected construction supports the requirement. Compare test data rather than assuming higher strength from GSM alone. |
| Surface and colour | Custom colours and acrylic-lacquered surface directions are published. | Approve a swatch, surface finish, cleaning compatibility and any branding requirement. |
| Seam and perimeter | High-frequency welding is a published fabrication direction; confirm the method for the selected material and design. | Agree seam layout, overlap, reinforcement zones and acceptance checks. |
| Outdoor performance | UV, cold-flex and heat-exposure requirements to be confirmed for the selected grade. | Specify destination conditions and request relevant grade-specific evidence. Do not transfer a claim from one material grade to another. |
Reference options are a sourcing starting point. The quotation and approved specification define the supplied material, finished-cover tolerances and any required tests.
At equal area, 900 gsm fabric is about 38% heavier than 650 gsm. For an illustrative 7.0 × 3.0 m flat panel, the fabric body weighs about 13.65 kg at 650 gsm or 18.90 kg at 900 gsm.
Fabric mass (kg) = length (m) × width (m) × GSM ÷ 1,000. This flat-panel estimate excludes cut-outs, overlaps, reinforcement, hems and hardware. It does not determine the correct cover size.
PVC coated polyester is a practical starting point for reusable covers requiring a continuous protective surface, welded panel construction and reinforced attachments. Verify coating adhesion, tear behaviour, cold flexibility and seam performance for the chosen grade.
A lightweight PE tarp may suit temporary protection when its actual grade meets the duty. Mesh can support airflow and debris control, but it does not provide a continuous rain barrier. Compare materials against the operating requirement rather than a universal material ranking.
Edges, seams and fastening
Container-cover hardware should follow the actual attachment map. A generic grommet pitch can produce a strong tarp that still cannot fit the unit. For custom heavy duty tarp fabrication, identify each interface on the drawing before the first sample is made.
Agree the welding method for the selected coated fabric. Show seam positions relative to bow contact, corners and repeated fold lines. If stitching is required in a detail, define its sealing and water-entry implications.
Map corner patches, extra fabric layers, webbing or rope-edge requirements to the local load path. Include reinforcement geometry and eyelet backing details rather than requesting only “extra strong edges.”
For TIR-cable-compatible layouts, send the operator’s fastening pattern and required eyelet opening. State whether cables, straps or other accessories are included in the quotation or supplied separately.
| Field observation | Check first | Specification action |
|---|---|---|
| Water collects in a low area | Support profile, loose spans and discharge path. | Review the support and fit together. Avoid creating unsupported pockets; do not rely on fabric weight to fix drainage. |
| Wear repeats over a bow or corner | Contact point, burrs, cargo edge and movement. | Address the contact surface and agree a localized abrasion layer or protective pad. |
| Holes elongate or pull out | Misaligned fittings, concentrated tension and reinforcement area. | Correct the hardware map and distribute local load through the approved perimeter detail. |
| Edges flap during exposure | Excess fabric, attachment gaps and unsupported spans. | Correct the pattern and fastening arrangement; reassess after installation and handling. |
Water adds load quickly: 10 mm of pooled water over 1 m² is approximately 10 litres, or 10 kg. This is a physical illustration, not an allowable tarp load. Keep the intended support and runoff path clear.
The tarp provides weather protection. Cargo blocking and lashing require their own securing plan. Avoid standing on an unsupported cover and use suitable access equipment for roof work; the CTU Code addresses securing and safe access separately.[2]
From sample approval to replacement stock
Approve one identifiable reference cover, its drawing revision and the material specification. Then agree which checks are routine, which use sampling and which need a test report. DERFLEX’s published quality-control workflow includes material verification, process monitoring, laboratory checks and shipment inspection.
| Checkpoint | Review against the approved reference | Record to retain |
|---|---|---|
| Material identity | Base construction, GSM, selected grade, colour and finish. | Material reference, batch identity and agreed supporting results. |
| Finished dimensions | Overall size, drops, reliefs and hardware centres under the agreed measuring condition. | Measurement record with explicit tolerances and front/rear orientation. |
| Panel joints | Seam position, continuity and any sample weld or water-ingress check agreed for the project. | Inspection method, sampling scope and pass/fail criterion. |
| Edges and hardware | Reinforcement location, eyelet openings, count and fit with the intended cable or straps. | Detail photos and trial-fit confirmation on the intended container configuration. |
| Packaging and identification | Drawing/SKU revision, front/rear labels, fold method and carton marks. | A packing reference that identifies the correct cover without fully unfolding it. |
Fit the sample on the intended container model with its normal supports and accessories. Check alignment, corner clearance and installation sequence. Photograph the approved arrangement so receiving and maintenance teams share the same reference.
A water-shedding cover does not eliminate humidity already present in cargo, timber or packaging. Assess moisture-sensitive shipments separately. Dry packing materials and the cargo-specific moisture plan remain relevant even when the outer cover is intact.[2]
DERFLEX supply approach
DERFLEX publishes container-cover PVC fabric options, high-frequency welding, colour and surface-finish directions. Its broader coated-fabric production and inspection workflow supports a technical discussion around the material, fabrication and repeat-order requirements.
Review the DERFLEX production workflow, then submit the cover drawing and the performance evidence you require. Confirm whether the quotation covers roll material, cut panels or a finished assembly.
Make the quotation comparable
Price depends on finished area, material grade, panel layout, reinforcement, hardware and order quantity. MOQ, sample arrangements and lead time should be quoted for the actual construction. For multi-size stock or private-label supply, include your wholesale and repeat-order requirements.
Buyer questions
Use the actual container and an approved drawing, not its nominal length alone. Measure the supported cover path, side and end overlaps, corner reliefs and attachment positions. Roof-opening dimensions are not finished tarp dimensions, and covers can differ between container models.
Compare handling weight, material construction and the required performance. DERFLEX publishes both material directions. For the same area, 900 gsm fabric has about 38% more mass than 650 gsm. This does not by itself prove greater finished-cover strength; verify the selected grade, seams, reinforcement and fit.
PVC coated fabric can provide a continuous water barrier, but the finished cover also depends on seams, edge overlap, drainage, support and wear. Agree a finished-cover water-ingress check if the cargo requires it. A rain cover does not remove humidity already inside cargo or packaging.
Use the attachment arrangement specified for the container, such as eyelets aligned with bars or rings and a compatible cable or strap system. Map the hardware positions and opening sizes on the drawing. Secure cargo independently; the weather cover does not replace cargo blocking or lashing.
DERFLEX can review drawing-based dimensions, PVC fabric options, seam construction, reinforcement, fastening details, colour, printing and packaging. Send the container configuration, drawing or sample, quantity and destination. Confirm the finished assembly and any accessories in the quotation scope.
Finished area, fabric grade, fabrication, reinforcement, hardware, printing, packaging and quantity affect the quotation. MOQ, sampling arrangements and production timing should be confirmed for the actual order. Compare suppliers using the same drawing, material specification and scope of supply.
[1] Container geometry: Hapag-Lloyd 20 ft open-top and 40 ft open-top fleet examples. Verify the specific unit before fabrication.
[2] Packing and securing: IMO/ILO/UNECE CTU Code, including cargo securing, condensation prevention and safe access guidance. Apply the operator’s instructions to the intended shipment.
Start with the container, not just the tarp size
Share the container type, supported cover profile, fastening map, material direction, quantity and destination. DERFLEX can review the scope needed for a sample, a production quotation or a repeat supply programme.