HT-5020 is intended for semi-intensive rooftop landscapes that need a deeper planting profile than a shallow extensive system. Its published nominal dimensions are 500 × 500 × 200 mm, giving each unit a 0.25 m² footprint and a theoretical coverage rate of four units per square metre.
The system uses three principal components: a structural tray, a raised filter plate and a snap-fit connector between adjacent units. These components organise the planting and internal drainage functions within a repeatable module. They do not replace the project-specific work required for structural loading, waterproofing, roof drainage, growing medium, irrigation, perimeter details or maintenance access.
The 200 mm dimension is the nominal overall tray height, not an automatic guarantee of 200 mm of usable growing medium. Effective substrate depth depends on the filter and drainage space, fill level, settlement allowance and the approved landscape build-up.
HT-5020 Project-Planning Summary
| Item | Planning basis |
|---|---|
| System role | Semi-intensive rooftop planting |
| Nominal unit size | 500 × 500 × 200 mm |
| Nominal footprint | 0.25 m² per unit |
| Theoretical coverage | 4 units per m² of net module-covered area |
| Main components | Structural tray, raised filter plate and inter-module connector |
| Planting direction | Groundcovers, herbaceous perennials, ornamental grasses and selected low shrubs, subject to project design |
| Separate project checks | Structure, waterproofing, root protection, primary drainage, substrate, irrigation, edges, access and local requirements |
What the 200 mm Profile Means for Planting Design
A 200 mm tray profile creates more potential root-zone space than a shallow extensive unit, but tray height is only one input in the planting design. The landscape designer must also define the effective growing-medium depth, substrate properties, finished level, expected settlement and the mature size and root habit of the selected vegetation.
Semi-intensive is a useful project category, but definitions vary between markets and standards. The final classification should reflect the complete roof build-up, plant palette, irrigation strategy and maintenance level—not the tray dimension alone.
The deeper profile can support a broader planting concept than low-profile sedum coverage. Groundcovers, flowering perennials, ornamental grasses and selected low shrubs may be considered where the effective substrate depth, local climate, roof exposure, irrigation and maintenance plan are suitable. Plant selection should be confirmed by a qualified landscape professional familiar with the project location.
How the Three-Part HT-5020 Assembly Works
1. Structural tray
The tray contains the growing medium and provides the geometry for the internal drainage zone. Its 500 × 500 mm footprint also provides a regular planning grid for setting out the planted area.
The tray must not be used as the sole basis for a structural decision. Roof loading has to be assessed for the complete installed system under the relevant project conditions.
2. Raised filter plate
The molded filter plate separates the growing medium from the lower drainage space inside the unit. This helps limit substrate migration into the internal flow paths while maintaining a defined planting zone above them.
This component does not eliminate every geotextile or separation layer on the roof. Waterproofing protection, root resistance, separation courses and other layers below or around the modules remain subject to the roof consultant’s details and the waterproofing manufacturer’s requirements.
3. Inter-module connector
The connector joins adjacent units and helps maintain the planned grid. Connector orientation and the relationship between modules, roof falls and outlets should be shown on the approved layout or shop drawing.
Supply scopes can differ by order. Before procurement, confirm whether the quotation covers the three plastic components only or also includes any substrate, vegetation, irrigation items, edge components or other accessories.
Plan the Complete Roof Before Ordering
Confirm structural capacity
A competent structural professional should assess the full roof build-up, not only an empty unit. The review should include the roof structure, waterproofing and protection layers, modules, growing medium, retained water, mature vegetation, irrigation components, edge or restraint details, maintenance access and any climate-specific loads required by local rules.
Use project-specific dry, wet and saturated design information where applicable. Do not substitute an unverified generic load figure for a structural calculation.
Coordinate waterproofing and root protection
Confirm the waterproofing system, root-resistance strategy, protection course, inspection procedure and warranty conditions before modules cover the roof. Penetrations, movement joints and transitions at parapets or upstands should remain consistent with the approved roof details.
Where the project uses leak detection or requires a pre-cover inspection, include that step in the installation sequence.
Map roof drainage and inspection zones
The primary roof drainage system must continue to manage runoff independently of the modules. Mark all drains, overflow points, scuppers, valleys and changes in roof fall on the layout. Keep inspection access clear and detail how the planted zones terminate around outlets and roof equipment.
The internal tray channels and connectors should be coordinated with the roof falls, but they do not replace the roof’s primary drainage design. Outlet capacity and emergency overflow provisions remain project-specific engineering decisions.
Specify growing medium and planting
Select a growing medium designed for rooftop use and for the intended vegetation. Its depth, density, drainage behaviour, water-holding characteristics and settlement should be confirmed as part of the landscape and structural design.
The nominal 200 mm tray height should not be copied directly into a specification as the guaranteed growing-medium depth. Confirm the actual section after accounting for the filter plate, drainage space, fill level, freeboard where required and anticipated settlement.
Decide the irrigation approach
Irrigation requirements depend on climate, seasonal rainfall, wind exposure, solar exposure, plant selection and the maintenance plan. Establishment watering may be required even where permanent irrigation is not specified.
If a permanent system is planned, coordinate the water source, pressure, zoning, pipe routes, accessible valves, emitters, winterisation where relevant and maintenance access. Confirm proposed routes and connection details against the current HT-5020 drawings before installation.
Detail boundaries and interfaces
Plan the transitions at parapets, façades, walkways, roof equipment, expansion joints and non-planted zones. Edge restraint, wind exposure, vegetation-free or fire-safety zones and access requirements should be determined by the project designer and applicable local rules.
Do not assume that a standard module layout resolves every perimeter or penetration condition. Use project details for all interfaces.
Module Layout and Preliminary Quantity Calculation
Use the net area that will actually be covered by HT-5020 units, rather than the gross roof area.
Preliminary unit quantity = net module-covered area in m² × 4
For example, a net module-covered area of 100 m² gives a preliminary quantity of 400 units. This is a planning quantity only. The final order should be based on the approved setting-out drawing after accounting for drains, access routes, perimeter bands, equipment zones, irregular geometry, mock-ups and any agreed project allowance.
A 500 mm planning grid can help the design team coordinate boundaries and minimise unresolved gaps. Confirm the final layout, component count and packing information with the supplier before arranging delivery or roof lifting.
Installation and Logistics Questions to Resolve
Before materials arrive on site, the project team should agree on:
- the approved roof and module layout;
- the waterproofing inspection and handover point;
- roof access, lifting method and permitted staging areas;
- the order in which connectors, trays, filter plates, substrate, irrigation and plants will be installed;
- temporary protection for completed waterproofing and finished areas;
- access to drains and roof equipment during and after installation;
- quality checks for alignment, component engagement, finished substrate level and drainage access; and
- the maintenance responsibility after planting.
Staged loading is especially important on a roof. Storage positions and installation sequencing should follow the structural engineer’s and site manager’s instructions.
When HT-5020 May Be the Appropriate Option
HT-5020 may be considered where the design calls for a semi-intensive landscape with more rooting space and a broader plant palette than a shallow extensive system can provide. It is most relevant when the project team is prepared to coordinate the additional structural, substrate, irrigation and maintenance requirements associated with a deeper rooftop landscape.
For a side-by-side view of the shallow HT-508 option and the deeper HT-5020 option, see our HT-508 and HT-5020 system overview.
Product selection should follow the roof structure, intended vegetation, effective substrate depth, water-management strategy and maintenance plan. A deeper unit is not automatically the correct choice for every roof.
Information to Include in an HT-5020 Project Enquiry
- project country and city;
- roof plan and net proposed planted area;
- building and roof type;
- roof falls, drain locations and perimeter conditions;
- intended vegetation and target effective growing-medium depth;
- irrigation concept;
- relevant structural or waterproofing constraints already identified by the project team;
- whether the request is for budget planning, a project quotation, distribution or a sample; and
- required delivery stage or programme.
This information helps confirm the preliminary quantity, component scope and documentation needed for the next design stage. Final structural, waterproofing, drainage and landscape approval remains with the project’s qualified professionals.
HT-5020 Semi-Intensive Green Roof FAQ
Is HT-5020 a 200 mm planting-depth system?
HT-5020 has a nominal overall tray height of 200 mm. That should not be interpreted automatically as 200 mm of usable growing medium. The effective substrate depth must be confirmed from the approved section after allowing for the filter plate, drainage space, fill level, freeboard where required and settlement.
How many HT-5020 units are required per square metre?
Each unit has a nominal 500 × 500 mm footprint, equal to 0.25 m², so the theoretical coverage is four units per square metre of net module-covered area. Final quantities must follow the approved layout and project allowances.
What are the main HT-5020 components?
The published system uses a structural tray, a raised filter plate and a snap-fit connector between adjacent units. Confirm the current bill of materials and whether substrate, plants, irrigation or edge accessories are included in the quoted supply scope.
Does the raised filter plate remove the need for all geotextiles?
No. It performs a separation function inside the module. Any root barrier, waterproofing protection, geotextile or other separation layer required elsewhere in the roof build-up must still be specified by the project team.
What plants can be considered for HT-5020?
Possible planting directions include groundcovers, herbaceous perennials, ornamental grasses and selected low shrubs. Suitability depends on effective substrate depth, mature root habit, climate, roof exposure, irrigation and maintenance. A local landscape professional should approve the final plant palette.
How should the project load be calculated?
A structural professional should calculate the complete installed build-up under the relevant dry, wet and saturated conditions, together with other applicable permanent, maintenance and climate loads. An empty-tray figure is not enough for structural approval.
Is irrigation required for an HT-5020 semi-intensive roof?
The answer depends on local climate, rainfall, exposure, substrate and planting. Establishment watering should be planned, and permanent irrigation should be assessed where the plant palette or site conditions require it.
What information is needed for preliminary planning or quotation?
Provide the project location, roof plan, net planted area, roof falls and outlets, planting intent, target effective substrate depth, irrigation concept, procurement role and required programme. These inputs allow a more useful quantity and component review.
Plan Around Verified Project Data
HT-5020 provides a defined 500 × 500 × 200 mm module and a three-part assembly for semi-intensive rooftop planting. A successful specification, however, depends on the complete roof—not on the product dimension alone.
Start with the structural review, roof drainage, waterproofing, effective substrate depth, plant palette, irrigation and maintenance plan. Then use the approved layout to confirm quantities and component scope.
Send LEIYUAN the roof plan, net planted area, project location and planting intent for a preliminary module quantity and supply-scope discussion.
Last reviewed: August 2026. This article provides general project-planning guidance and does not replace structural, roofing, drainage, landscape or code approval.