COSHH · Mandatory · Construction

Substance Inventory and Hazmat Register

The Substance Inventory and Hazmat Register is a live record of all hazardous substances brought onto site, their locations, quantities, and associated safety data sheets. It enables emergency responders to identify hazards quickly and ensures all substances have been assessed under COSHH before use. The register must be updated whenever new substances arrive on site.

Last reviewed: 29 March 2026 — This guide reflects UK law as of this date. COSHH Regs 2002 remains current with no amendments enacted as of 29 March 2026. Next scheduled review: 29 March 2027.

What it records	Every hazardous substance present on site — product name, CAS number, SDS reference, GHS/CLP classification, storage location, maximum quantities held, COSHH assessment reference, and emergency procedure reference
Legal basis	COSHH Regulations 2002 (Regulations 6 and 12), MHSWR 1999 Regulation 3, DSEAR 2002
SDS requirement	A current REACH-compliant 16-section Safety Data Sheet must be held for every substance on the register
Emergency use	The register must be accessible to the Fire and Rescue Service in the event of an incident
Who maintains it	The Principal Contractor maintains the site-wide register; subcontractors must add every substance they bring to site

1. Why a Site Hazmat Register Is Essential

A construction site may have dozens of hazardous substances present at any one time — adhesives, solvents, sealants, fuels, cleaning agents, paints, resins, curing compounds, and specialist chemicals brought by multiple subcontractors. Without a single, centralised register, no one on site has a complete picture of what is stored where, in what quantities, or what the combined risk profile looks like. The Substance Inventory, also referred to as the Site Hazmat Register, exists to provide that picture.

The register is not an administrative exercise. It serves three critical functions. First, it provides the information needed to carry out COSHH assessments — without knowing what substances are on site, a suitable and sufficient assessment under Regulation 6 of COSHH is impossible. Second, it enables the Principal Contractor to manage dangerous substance risks under DSEAR 2002, including identifying storage incompatibilities, assessing explosion risk, and ensuring that flammable and oxidising materials are not stored in proximity. Third, it provides the Fire and Rescue Service with immediate access to the information they need to respond safely to a fire or chemical incident on site — what substances are present, where they are stored, and what the hazard classifications are.

COSHH Regulation 12 requires employers to ensure that substances hazardous to health are used, handled, and stored in a manner that prevents or adequately controls exposure. This cannot be achieved without first knowing exactly what substances are present. The register is the foundation upon which all other COSHH and DSEAR compliance activities are built. If the register is incomplete, inaccurate, or out of date, the entire compliance chain downstream is compromised.

The register is a living document — it must be updated every time a new substance arrives on site

A Hazmat Register that was compiled at the start of the project and never updated is of very limited value. Subcontractors bring new products to site throughout the construction programme. Substitutions are made. Suppliers change formulations. The register must be updated every time a new substance is introduced, every time a product is substituted, and every time an SDS is revised by the supplier. The Principal Contractor’s site induction and delivery acceptance procedures should include a step that requires any new substance to be registered before it is used or stored on site.

2. What the Register Must Contain

The register should record sufficient information to identify each substance, locate it on site, understand its hazard classification, and cross-reference it to the relevant SDS, COSHH assessment, and emergency procedure. The following table sets out the minimum fields that a compliant Hazmat Register should contain.

Field	Description	Why it matters
Product name	The commercial or trade name of the substance as it appears on the container label	Enables identification on site and cross-referencing with the SDS and COSHH assessment
Supplier	The name of the manufacturer or supplier who provided the substance	Required to obtain or chase updated SDS; identifies the responsible party under REACH
CAS number	The Chemical Abstracts Service registry number — a unique numerical identifier for each chemical substance	Eliminates ambiguity where the same substance is sold under different trade names by different suppliers
SDS reference and date	The document reference number and issue date of the Safety Data Sheet held on file	Confirms that a current SDS is available and enables version control; an outdated SDS may contain superseded safety information
GHS/CLP classification	The hazard classification under the CLP Regulation — hazard pictograms, signal word, and hazard statements (H-codes)	Identifies the nature of the hazard (flammable, toxic, corrosive, etc.) and enables storage compatibility checks
Storage location	The specific location on site where the substance is stored — building, room, cage, or COSHH cabinet reference	Enables Fire and Rescue to locate substances during an incident; enables the PC to verify storage conditions and compatibility
Maximum quantity	The maximum quantity of the substance that will be held on site at any one time	Required for DSEAR risk assessment; determines whether COMAH thresholds are approached; informs fire risk assessment
COSHH assessment reference	The reference number of the COSHH assessment that covers the use of this substance	Confirms that the substance has been assessed under Regulation 6 and that control measures have been identified
Emergency procedure	Reference to the emergency procedure or spill response plan applicable to the substance	Ensures that first responders and emergency services can access the correct emergency information immediately
Date added	The date the substance was first entered on the register	Provides an audit trail and enables the PC to identify substances that were introduced without going through the registration process

Storage compatibility is a legal requirement under DSEAR

The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) require employers to assess the risks from dangerous substances in the workplace and to ensure that incompatible substances are not stored together. Flammable liquids must not be stored alongside oxidisers. Acids must not be stored with bases. The Hazmat Register provides the information needed to identify incompatibilities and plan storage arrangements that comply with DSEAR. Without a complete register, storage compatibility cannot be assessed.

3. Common Mistakes

Not requiring subcontractors to register their substances

The Principal Contractor is responsible for the site-wide Hazmat Register, but subcontractors bring the majority of hazardous substances to site. If the PC does not have a clear, enforceable process requiring every subcontractor to register every substance before it is used or stored, the register will be incomplete from day one. Site induction, delivery acceptance procedures, and subcontract conditions should all include a requirement to register substances. A register that only contains the PC’s own substances is not a site-wide register and does not satisfy COSHH Regulation 6.

Not keeping Safety Data Sheets current

An SDS that is several years old may contain outdated exposure limits, superseded first aid measures, or incorrect hazard classifications. REACH requires suppliers to update SDS when new information becomes available. The register must record the SDS issue date and the date it was received, and a review process must be in place to ensure that the most current version is held. Using a product on the basis of an outdated SDS means that the COSHH assessment derived from it may also be incorrect.

Storing the register only in the site office

The register must be accessible to the Fire and Rescue Service in the event of an emergency. If the register exists only as a paper file in the site office, and the site office is involved in the fire, the register is unavailable at the moment it is most needed. A copy should be held off site or in a fire-resistant location, and the Fire and Rescue Service should be informed of its location as part of the site emergency plan. Digital registers accessible from any device are the most practical solution.

Not including quantities

Recording the product name and classification without recording the quantity held on site makes it impossible to carry out a meaningful DSEAR risk assessment. The risk from 5 litres of a flammable solvent stored in a COSHH cabinet is fundamentally different from the risk of 500 litres stored in an open compound. Quantities also determine whether COMAH lower-tier thresholds are approached and inform the fire risk assessment. The register must include the maximum quantity that will be held on site at any one time.

Using the register as a substitute for COSHH assessments

The Hazmat Register records what substances are on site. A COSHH assessment evaluates the risk of exposure during the specific way the substance will be used on this project and identifies the control measures required. These are fundamentally different documents. Having a substance on the register does not mean it has been assessed under COSHH Regulation 6. The register should include a cross-reference to the COSHH assessment for each substance, and any substance without a completed COSHH assessment should not be used on site.

4. Related Documents

The Substance Inventory sits at the centre of a network of COSHH, DSEAR, and emergency planning documents. The following table describes how it relates to each.

Document	Relationship
C1 — General Site Induction	The site induction should include a requirement for all personnel to notify the PC of any hazardous substance they intend to bring to site. The induction ensures that every worker understands the registration process and the location of the Hazmat Register and associated SDS files.
C14 — SDS Register	The SDS Register holds the actual Safety Data Sheets for every substance listed in the Hazmat Register. Each entry in the Hazmat Register must cross-reference the corresponding SDS by document reference and issue date. The two registers work together: the Hazmat Register provides the summary; the SDS Register provides the detailed 16-section safety information.
F11 — Fire Risk Assessment	The Fire Risk Assessment must take account of all flammable and combustible substances stored on site. The Hazmat Register provides the information needed to identify these substances, their storage locations, and the quantities held. Without a complete Hazmat Register, the Fire Risk Assessment cannot be suitable and sufficient.
F14 — Emergency Plan	The site Emergency Plan must include procedures for responding to chemical spills, fires involving hazardous substances, and exposure incidents. The Hazmat Register provides the emergency responders with the information they need to identify substances involved and access the correct emergency procedures. The Emergency Plan should reference the Hazmat Register and confirm its location.

5. Frequently Asked Questions

Is a Substance Inventory / Hazmat Register a legal requirement?▾

There is no single regulation that mandates a document called a "Hazmat Register" by name. However, COSHH Regulation 6 requires a suitable and sufficient assessment of the risk from every substance hazardous to health used at work, and Regulation 12 requires proper use, handling, and storage. DSEAR 2002 requires an assessment of risks from dangerous substances and the identification of hazardous zones. MHSWR 1999 Regulation 3 requires a risk assessment covering all work activities. In practice, maintaining a centralised register of all hazardous substances on site is the only way to demonstrate compliance with these overlapping obligations. An enforcing authority or court will expect to see one.

What happens if an unexpected substance is found on site?▾

If a substance is discovered on site that is not on the Hazmat Register, work involving that substance must stop immediately. The substance must be identified, the SDS must be obtained, and it must be entered on the register before any further use or storage. A COSHH assessment must then be completed. The PC should investigate how the substance arrived on site without being registered, and should take corrective action to prevent recurrence — whether that means reinforcing the induction process, tightening delivery acceptance procedures, or addressing non-compliance with the relevant subcontractor.

What DSEAR information should the register capture?▾

For substances that are classified as flammable, highly flammable, extremely flammable, or oxidising under CLP, the register should record sufficient information to support a DSEAR risk assessment. This includes the maximum quantity held on site, the storage location and conditions, whether the substance produces a flammable atmosphere during use (e.g. solvent vapour during application), the flash point and autoignition temperature (available from SDS Section 9), and any incompatible substances stored nearby. This information enables the PC to identify whether hazardous zones need to be designated and whether additional explosion protection measures are required.

How long should records be kept after the project is completed?▾

COSHH Regulation 11 requires health surveillance records to be kept for 40 years. While the Hazmat Register itself does not have a specified retention period, it is part of the evidence trail that supports health surveillance and COSHH assessments. Best practice is to retain the Hazmat Register and all associated SDS files for the duration of the project plus a minimum of 40 years, consistent with the health surveillance retention requirement. This is particularly important for substances that may cause long-latency occupational diseases — some cancers and respiratory conditions can take decades to manifest after exposure.

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