RTEC KNOWLEDGE HUB

LECA in Data Centres & Mission-Critical Buildings

Lightweight Aggregate for Roof Build-Ups, Drainage, Landscaping and Selected Civil Engineering Applications

Foreword

Data centres are indispensable to the digital economy. Their buildings must accommodate substantial mechanical and electrical infrastructure while meeting demanding requirements for structural integrity, drainage, environmental control, fire safety and operational continuity. Although computing equipment attracts considerable attention, the supporting civil engineering deserves equal care.

Lightweight Expanded Clay Aggregate (LECA), also known as Expanded Clay Aggregate (ECA), merits consideration for certain supporting construction applications. Its suitability, however, depends on the intended function, the selected grade and the engineering specification. It is not a universal construction solution, nor does its use independently confer mission-critical resilience.

Preface

This article examines where LECA may be evaluated in data-centre campuses and other mission-critical buildings. It considers roof build-ups, drainage, landscaping and selected engineered fills, while distinguishing material supply from structural design, specialist engineering and installation responsibilities.

1. Beyond the Server Hall

A data-centre campus encompasses more than server rooms. Its infrastructure may include extensive roofs, plant areas, electrical yards, access roads, utility corridors, stormwater systems, perimeter planting and ancillary buildings. Each component has specific loading, drainage, durability and maintenance requirements.

Where thick granular fills are required, the weight of conventional materials may be a significant design consideration. In suitable applications, lightweight aggregate can provide an alternative worth assessing. The decision must be based on verified material properties and project-specific calculations rather than the assumption that lighter is invariably better.

2. Understanding LECA/ECA

LECA is manufactured by expanding suitable clay at high temperatures. The resulting particles generally have a porous internal structure and a comparatively hard outer surface. Available grades differ in particle size, grading, density and physical characteristics.

These properties can be relevant to lightweight filling, drainage and certain landscape applications. Nevertheless, bulk density, crushing resistance, water absorption, hydraulic behaviour and grading must be verified for the specific product and proposed use.

3. Potential Areas of Application

3.1 Lightweight roof build-ups

Some roof assemblies incorporate levelling fills, drainage layers or landscape components. Where the complete roof design permits a lightweight granular material, LECA may be evaluated as one component of the assembly.

The design must account for installed density, moisture, thickness, compaction where applicable, containment and the loads imposed on the supporting structure. LECA does not replace the waterproofing membrane, thermal insulation or a properly designed drainage system.

3.2 Drainage and stormwater management

Data-centre campuses may have substantial roof catchments and paved surfaces. Their stormwater arrangements must be designed around rainfall, runoff, site levels, discharge constraints and applicable regulations.

LECA may be considered for selected drainage layers in compatible roof and landscape assemblies. Filtration and biofiltration applications require separate evaluation of particle grading, hydraulic conductivity, clogging potential, filter compatibility and the relevant water-quality objectives. Porosity alone does not establish treatment performance.

3.3 Landscape and podium systems

Landscaped areas can soften the built environment and support carefully planned site development. Where growing systems are located above structures, dead load and drainage are important design considerations.

LECA may be assessed as a drainage component or as part of a specified growing-medium blend. It must not be assumed that every aggregate grade is suitable for horticulture or that aggregate alone constitutes a complete growing medium. Plant requirements, water retention, aeration, irrigation and root-zone design remain essential.

3.4 Selected engineered fills

Certain ancillary civil works may present constraints associated with ground loading or settlement. Lightweight aggregate can be investigated where a geotechnical design identifies a suitable application.

Suitability for foundations, pavement sub-bases, cable trenches, buried services or structural bearing zones must never be inferred from low weight alone. Bearing capacity, settlement, particle degradation, containment, compaction and groundwater exposure require professional assessment.

4. Illustrative Application Map

The following schematic identifies possible areas for investigation. It is conceptual and does not represent a construction detail, approved design or a claim that every application is suitable for every facility.

5. Cooling, Fire Safety and Operational Resilience

Data-centre cooling relies on carefully engineered mechanical systems, airflow management, heat rejection and control strategies. LECA should not be described as a direct cooling solution or as a proven means of reducing power usage effectiveness (PUE) without relevant test data and project-specific evidence.

Likewise, manufacture at high temperatures does not establish the fire rating of a complete roof, wall or floor assembly. The project team must confirm applicable product documentation, system test evidence and statutory requirements. LECA cannot replace fire compartmentation, fire-stopping, detection or suppression.

6. The Specification Checklist

• Define the exact application and performance requirement.
• Specify particle size and acceptable grading tolerances.
• Verify bulk density and expected installed density.
• Calculate dead load for the proposed thickness and service conditions.
• Check drainage, water retention or filtration properties as applicable.
• Assess crushing resistance, durability and moisture exposure.
• Confirm compatibility with waterproofing, insulation, geotextiles and adjacent materials.
• Establish containment, separation, installation and inspection requirements.
• Obtain product documentation and any testing required by the project consultant.

7. A Second Look: The Engineering Selection Process

8. RTEC Inc. and Product Supply

RTEC Inc. supplies LECA/ECA for selected construction, drainage, landscaping and related applications. For a data-centre or mission-critical project, the practical starting point is to identify the intended use, particle-size requirement, estimated quantity and delivery destination.

Material supply and product-related information must be distinguished from specialist engineering services. Structural calculations, geotechnical assessments, fire certification, thermal modelling and installation design should be undertaken or approved by the appropriately qualified project professionals.

9. Conclusion

Mission-critical infrastructure demands materials selected with precision. LECA may merit consideration in specified roof build-ups, drainage layers, landscape systems and selected engineered fills where its verified properties meet the project requirements.

The correct approach is neither to dismiss lightweight aggregate nor to assume that it is universally suitable. It is to define the application, verify the material, assess the complete construction system and obtain the necessary engineering approval.

RTEC Inc. welcomes enquiries from data-centre developers, EPC contractors, civil engineers, roofing specialists, landscape contractors and infrastructure procurement teams seeking LECA/ECA for defined applications.

Glossary

LECA/ECA: Lightweight Expanded Clay Aggregate or Expanded Clay Aggregate; a granular material manufactured by expanding suitable clay at high temperatures.

Bulk density: Mass per unit volume of a bulk quantity of aggregate, including the spaces between particles. The measurement method and condition must be stated.

Dead load: The permanent weight of a building element or material imposed on the supporting structure.

Hydraulic conductivity: A measure of a material's ability to transmit water under a hydraulic gradient.

Mission-critical facility: A facility whose function requires a high degree of operational continuity and carefully managed risks.

PUE: Power Usage Effectiveness, a data-centre energy-efficiency metric comparing total facility energy with IT equipment energy.

Geotechnical engineering: The branch of engineering concerned with soil, rock, groundwater and their interaction with constructed works.

Biofiltration: A process in which a designed medium and associated biological, physical and chemical mechanisms help treat water. Performance depends on the complete system.

References and Further Reading

1. ACI 213R, Guide for Structural Lightweight-Aggregate Concrete. Consult the applicable edition for background on structural lightweight aggregate concrete; its provisions should not automatically be applied to loose-fill LECA.
2. ACI 318, Building Code Requirements for Structural Concrete. Relevant where structural concrete is involved, subject to the adopted code and project requirements.
3. ASHRAE, Thermal Guidelines for Data Processing Environments. Background on environmental conditions for IT equipment; not a specification for LECA.
4. Applicable local building regulations, fire and life-safety codes, roof-system specifications and stormwater-management requirements.
5. Product-specific technical data, grading information and test reports for the proposed LECA/ECA grade, together with project consultant requirements.

The references above are starting points for professional review, not evidence that any particular LECA product has been certified for a specific data-centre application. Verify the current edition, applicable jurisdiction and project requirements before specification.

Copyright and Use

© 2026 RTEC Inc. All rights reserved. This article is provided for general technical awareness and material-selection discussion. It is not a substitute for project-specific design, testing, regulatory review or professional engineering advice. Product properties and suitability must be verified for the intended application. No performance guarantee is implied for a complete construction system.

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