Heavy Duty Soakaway Crate Manufacturers: Ratings, Tests and Supply Compared

Updated October 2026

Heavy duty soakaway crate manufacturers selling into the UK list short-term vertical strengths between about 390 and 702 kN/m² for their trafficked ranges. Means of measurement differ. This guide compares eight ranges on a level basis, shows which test produced each figure, and sets out what the buried crate needs before a lorry drives over it.

Heavy Duty Soakaway Crate Manufacturers Supplying the UK

Heavy duty soakaway crate manufacturers supplying the UK can be placed in three groups. The first is the leading UK range, distributed via builders’ merchants (Polypipe, Wavin, ACO, Brett Martin, etc.). The second is made up of European manufacturers with a presence in the UK (GRAF). The last group is made up of manufacturers who export direct from the factory, such as Storm Manage. Each group has different ways of presenting their load data, and therefore the table only includes data as it’s presented by each group.

Polypipe makes the Polystorm family, and its datasheets give two different strengths for two different cells. The standard Polystorm cell lists 44 tonnes/m², while Polystorm-R lists 61 tonnes/m² from over 90% recycled material. The Polypipe Polystorm soakaway crate also takes 300mm and 450mm flange adapters. Those adapters join the tank to Ridgidrain underground drainage pipes, so the crates and the drainage network can come from one maker.

Access for inspections is standard on EcoBloc Inspect flex, with GRAF building a channel for standard inspection cameras. Wavin aims AquaCell Plus-R at applications where inspectability is required, and Polypipe access is provided by separate Polystorm Access & Inspect units. StormMaster figures come from the Plastech Southern brochure for the system supplied by Balstreet Ltd. All figures are from each manufacturer’s datasheet or product page read in October 2026; ACO’s StormBrixx HD brochure is over 30 pages in length so it isn’t included in the table. The supply route affects lead time more than strength does. One UK merchant states orders of more than four crates may take 2 to 5 working days, and a factory-direct order adds production time and sea freight.

Storm Manage, the publisher of this guide, makes crates for drainage applications from driveways to lorry yards and ships its soakaway crates factory-direct from Shenzhen: production takes 3 to 10 days and a 40HQ container holds up to 330 m³ of installed storage, with a minimum order of 1 m³. Its vertical figures are based on the older CIRIA C680:2008 test method. That supply route is slower than a merchant pallet for a single driveway, and no Storm Manage grade yet has a BBA, Kiwa or WRc certificate. Buyers who also compare tank suppliers can see the wider attenuation tank manufacturers list.

What “Heavy Duty” Means on a Soakaway Crate Datasheet

Heavy duty on a soakaway crate datasheet means a short-term vertical compressive strength rated for vehicle loads; on the datasheets compared here, vehicle grades start at 40 t/m². The tonne figure is a pressure on the top face, and product specification sheets provide the value in t/m², kN/m², or both.

Three European standards define how these test numbers are produced. EN 17150 sets the short-term compression test, EN 17151 the long-term compression test and EN 17152-1 the product standard for PP and PVC-U boxes which are used in landscape, pedestrian or vehicular traffic areas. TEPPFA’s note on the three CEN standards describes them as the minimum requirements and a unified way of testing.

Tonnes convert at 9.81 kN/m² per t/m², so 60 t/m² is about 588 kN/m². Several UK datasheets round the factor to 10, which is why Polypipe prints 44 t/m² as 440 kN/m².

The common misreading is to treat 60 tonnes as a vehicle mass. A crate rated at 60 t/m² carries that pressure only on its top face in a press, and the wheel load reaching it depends on the cover and pavement above. The full load path is set out in our D400 load class guide.

Does a 60 tonne crate mean a 60 tonne lorry can drive over it?

No. A 60 tonne vertical load rating is a short-term pressure of roughly 588 kN/m² on the crate’s top face, measured in a test press. A 60 tonne lorry is a vehicle mass spread through tyres, pavement and cover, and makers tie lorry use to a minimum cover depth.

GRAF, for example, rates EcoBloc Inspect flex for 60 t lorries with 800 mm of earth cover, and Wavin lists 1.30 m of cover for their Plus-R crate for use under low speed roads carrying vehicles of less than 60 t. The class printed on manhole covers above is a different matter. BS EN 124-1 grades gully and manhole covers, and not the buried crate.

Crate Ratings for Driveways, Car Parks and HGV Yards

For a domestic driveway, Polypipe lists 0.50 to 0.65 m of cover for Polystorm-R; for car parks with vehicles up to 12 t, Wavin lists 0.69 to 0.81 m; and for HGV yards, makers list 0.80 to 1.30 m for high strength soakaways rated for 60 t vehicles. The table shows the references for the figures.

The figures belong to the product, so a figure from one row can’t be moved to another crate. Hydro International gives two worst cases in their design guidelines: the shallowest cover for wheel loads and deepest cover for the soil weight, and both of these limits need to be considered for your site. Our load-class and cover-depth selector runs the same two checks for each grade.

The fact that a crate can take the weight of an HGV doesn’t make infiltration acceptable on an HGV yard. Defra standard 4.9 names lorry, bus or coach parking and turning sites among uses that may need an Environmental Permit, and standard 4.16.1 asks for at least 1.0 m of unsaturated ground between the base of an infiltration-only feature and the maximum likely groundwater level. Where either fails, the same crates are wrapped in an impermeable membrane to temporarily store rainwater and release it at a controlled rate. In this role the crates function as attenuation crates, and a geocellular attenuation tank functions as the drainage solution instead of a soakaway. The heavy duty soakaway crate page gives the grades for both functions.

How deep should soakaway crates be installed?

Soakaway crates sit with 0.50 to 1.30 m of cover depending on the expected traffic, and manufacturers publish maximum burial depths of 3.7 to 7.8 m to the base. The deepest limit is Wavin’s figure for landscaped areas in dense sand and gravel. Polypipe lists 3.7 m for Polystorm under light traffic, Plastech 3.9 m for StormMaster, and GRAF up to 5 m for EcoBloc Inspect flex.

For Wavin’s Plus-R, maximum depth depends on the sub-soil condition. Under vehicles below 44 t, Wavin’s Plus-R table restricts the depth to 4.17 m in an over-consolidated stiff clay and 7.30 m in dense sand and gravel. A complete description of the procedure is found in our soakaway crate installation guide.

Comparing Manufacturer Figures on the Same Basis

Two geocellular crates sold as “60 tonne” can perform differently, as the headline number is a short-term vertical result, and a buried tank also depends on lateral strength and long-term strength. Check every shortlisted datasheet on the three values in kN/m², and then compare prices.

Three-Number Datasheet Read

The Three-Number Datasheet Read checks the short-term vertical, short-term lateral, and long-term strength in kN/m², converted with the same factor, and flags any datasheet that leaves a value empty.

Brett Martin includes all four values. The long-term vertical strength is 27% of the short-term value, and the long-term lateral is 19 kN/m². That ratio is unique to StormCrate55 and can’t be extrapolated to other crates, because long-term strength comes from each product’s own creep test.

Polypipe’s two cells show a second pattern. Polystorm-R raises vertical strength from 440 to 610 kN/m², a 39% increase, yet both cells list 63 kN/m² lateral. A deep tank next to a retaining wall is governed by side pressure, so the higher vertical figure buys nothing there.

Strength isn’t defined by resin type alone. Polystorm-R, made from over 90% recycled material, lists a higher vertical figure than the standard Polystorm cell, so ask for the test results rather than relying on “virgin” or “recycled” on the label. TEPPFA notes that EN 17152-1 takes account of the call for more recycled content.

The BPF Pipes Group paper on geocellular lifespan explains the long-term method: creep rupture tests are extrapolated to 50 years and the 95% lower confidence limit becomes the characteristic strength.

Test Reports and Certificates to Request Before You Order

When requesting heavy duty crates, contact the manufacturer for an EN 17150 short-term report in kN/m² for vertical and lateral loads, an EN 17151 long-term result, conformity with EN 17152-1, any third-party certificate such as BBA, and a structural analysis for your cover and traffic. EN 17152-1 covers boxes for infiltration applications, attenuation and storage, so ask which use the declaration names.

Failures usually trace back to design and installation rather than the box. A 2025 New Civil Engineer article on buried drainage design notes that CIRIA C737 lists insufficient structural and geotechnical design, and failure to consider ground conditions or unit deformation, as the first two contributing factors in most failures. Please complete the checklist below as part of your quote request.

Merchant private labels usually arrive with a brochure only, while UK brands with a BBA certificate and some factory-direct manufacturers can send laboratory reports. Storm Manage provides its Intertek and SGS compression reports per project and states that it has no EN 17151 report or BBA certificate, which a reviewer may handle as a departure from standard. The heavy duty supplier spec checklist covers the same items.

Heavy Duty Crates vs Rubble Soakaways and Arch Chambers

Heavy duty crates store about three times more water per cubic metre dug than a rubble soakaway under lorry traffic, because crates are about 95% void while the example in BRE Digest 365 is worked with a 30% free volume granular fill. Arch chambers are a third option for long, narrow runs.

Worked example, using void figures published by Polypipe and BRE: for 10 m³ of storage, crates at 95% voids need 10 / 0.95 = 10.5 m³ of crate volume, while rubble at 30% free volume needs 10 / 0.30 = 33.3 m³ of fill. That’s roughly 23 m³ more excavation and spoil to remove, before allowing for the working space around the tank. Less spoil would also reduce soil transport and installation time on a constricted site.

Susdrain’s geocellular storage component guidance sets maintenance as regular inspection of silt traps, manholes and pipework, with sediment removal as required. Water infiltration is fastest in sandy and loamy soils. Cotterills’ soakaway guide notes that clay-heavy soils have low permeability and aren’t always compatible with a soakaway system; in such cases, crates become an attenuation system with a controlled outlet.

On lorry yards, the infiltration limits from the ratings section still apply: Defra asks for at least 1 m of unsaturated ground above the maximum likely groundwater level, and lorry parking may require an Environmental Permit.

Where soakaway crates are used on larger sites, they are one of the components of surface water management. Permeable paving, grass swales and bioretention basins can slow and clean runoff before it reaches the tank, and therefore reduce the silt load on crates.

Crates are modular, so soakaway crate systems can be shaped to the plot; Polypipe lists Polystorm-R for shallow excavations, narrow strips and restricted areas. Our comparison of stormwater chambers vs modular crates covers footprint, depth and access for maintenance.

Price per Cubic Metre and How Supply Routes Change It

Crate-only prices for heavy duty soakaway crates in UK drainage merchant listings sat between about £138 and £248 per m³ ex VAT in October 2026, before membrane, excavation and installation. Factory-direct supply alters the price of the crates, while excavation, backfill and labour make up much of the installed cost.

How much do heavy duty soakaway crates cost per cubic metre?

Heavy duty soakaway crates cost about £138 to £248 per cubic metre ex VAT from UK merchants in October 2026. Polystorm cells listed at £27.59 to £41.58 per 0.2 m³ crate, and a 65 tonne Aqua Storm crate at £99 per 0.4 m³.

Divide the crate price per m³ by the void ratio to get the price per m³ of water stored; at 95% that adds about 5%. Prices fluctuate with resin and freight, and the Environment Agency’s SuDS cost estimation report states that published unit costs need adjusting for inflation, and costs specific to a site also depend on several factors.

Factory-direct supply alters the freight line and the duty base. According to HMRC’s Customs valuation guidance, separately paid transport is included in the value of imported goods, using the example of £100 of goods and £30 of transport valued together at £130. The transport cost included is the cost up to the point where the goods enter the UK. Crates that nest or pack flat reduce lorry loads: at Oakengates in Telford, a Susdrain case study records a 5:1 reduction in transport after switching to a geocellular system that packed efficiently.

Merchant stock suits a single driveway requiring 1 cubic metre to 3 m³ of crates. A factory-direct container is appropriate for housing developments, commercial applications and infrastructure projects with tanks of 100 m³ or more, where the crate line is large enough to absorb sea freight. Module sizes and kit contents are compared in our soakaway crate sizes and kits guide.

What Changed for UK Crate Specifiers in 2025

In 2025 England published new National Standards for Sustainable Drainage Systems on 19 June, and PD CEN/TS 17152-4, structural design guidance for modular crate systems, was published in the UK on 31 July. Both focus on the site’s structural design rather than the tonne rating.

The Defra standards are non-statutory in England. Standard 7.4 states that the surface water drainage system shall be designed to:

“…ensure structural integrity of all components under anticipated loading conditions for the design life of the development so that it does not affect the structural integrity of any existing or proposed components within, or adjacent to, the development.”

Wales already works to statutory standards: Natural Resources Wales states six, and S6 covers construction, operation and maintenance and structural integrity. A crate supplier serving both nations should expect the drainage approver to request the same evidence of structural integrity.

The design basis is still debated. CIRIA states that C737, published in April 2016, supersedes C680 and that designs should now be based on C737. The BPF Pipes Group position statement of November 2025 still describes C680 as an effective and conservative method and points to CEN TS 17152-4 as the European route.

The new PD CEN/TS 17152-4 guidance relates to systems made up of EN 17152-1 boxes. It excludes seismic loads, lateral loads from adjacent structures and embankments, the influence of trees, backfill outside CEN/TR 17179, and the geotextile or geomembrane wrap. A crate tank installed beside a building or an embankment should therefore get its own lateral check.

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