Gas Safety (Installation and Use) Regulations 1998 explained
They are the law on installing, maintaining and using gas appliances and pipework in Great Britain: SI 1998 No. 2451, with 43 numbered regulations in Parts A to G. The ones an engineer meets daily cover competence (3), tightness testing (22), post-work checks (26(9)), room-sealed rules (30), landlord checks (36) and escapes of gas (37).
Reviewed by Jordan Valentine-Dunn, Gas Safe registered engineer · Portsmouth Gas Heating · Last reviewed October 2026
The regulations are short, and most of an engineer's day sits in a score of them. The table below gives each in a line, quoting what legislation.gov.uk prints, and points to the page on this site that holds the detail. The numbering is the regulations' own, so GSIUR 26(9) and GSIUR 36(3) mean the same thing everywhere.
Which regulations does a gas engineer meet most often?
About twenty, listed below. They fall in Part B (fittings), Part D (pipework), Part E (appliances) and Part F (maintenance), with escapes of gas in Part G. Regulation 3 comes first because every other duty assumes the person doing the work is competent and, for most work, belongs to a class of persons approved by HSE.
| Regulation | What it requires, in a line |
|---|---|
| 3 Qualification and supervision | No one may work on a gas fitting unless competent; employers must ensure it; most work must be done by a member of a class of persons approved by HSE (replacing a hose or regulator on a portable heater, or a cylinder hose, is excepted) |
| 5 Materials and workmanship | Every part of a fitting must be of sound material, adequate strength and the right type for the gas; no lead pipe; work must follow appropriate standards |
| 6 General safety precautions | Make safe any gas that could be released, seal incomplete gasways, never use an ignition source when searching for a leak, and test for gas tightness straight after work that might affect it (6(6)) |
| 9 Emergency controls | Gas may not be supplied for the first time unless an appropriately sited emergency control with adequate access is provided, with its handle attached and open and shut positions marked |
| 15 Meters: emergency notices | A permanent notice at or near a new primary meter gives the procedure for an escape of gas, and one gives the control's position if it is more than 2 metres away or out of sight |
| 18 Safe use of pipes | Installation pipework must be where it can be used safely, allowing for other pipes, drains, cables and the structure; the installer must tell the responsible person if equipotential bonding may be needed |
| 19 Enclosed pipes | Rules for pipework in a wall, floor, cavity, shaft, duct or void, including movement protection and the sleeve through a cavity |
| 22 Testing and purging | After work that might affect gastightness the pipework must be tested and examined at once; where gas is supplied it must then be purged, sealed if not used, and any loosened connection retested |
| 26 Appliances: safety precautions | An appliance must be safe to use; a flued domestic appliance is connected by rigid pipe; after any work the engineer examines the flue, combustion air, operating pressure or heat input and operation (26(9)), and notifies any defect |
| 27 Flues | The flue must be suitable and in proper condition; a flue entering a chimney must have an inspectable seal; a power flue must shut the appliance down if the draught fails; no flue in an unsafe position |
| 28 and 29 Access and instructions | An appliance must be readily accessible for operation, inspection and maintenance, and the maker's instructions must be left for the owner or occupier |
| 30 Room-sealed appliances | Only room-sealed appliances in a bathroom or shower room; in sleeping accommodation, room-sealed unless a fire, space heater or water heater is 14 kW or less and meets the safety-control alternative |
| 33 Testing of appliances | When installing an appliance on a live supply, test its connection for gastightness and examine the installation, operating pressure and safety controls at once |
| 34 Use of appliances | The responsible person must not use an appliance they know or suspect is dangerous; any person working on gas who suspects a dangerous appliance must take reasonably practicable steps to inform the responsible person (34(3)) |
| 35 and 36 Maintenance and landlords | Employers and the self-employed keep appliances, pipework and flues safe at work; landlords have each appliance and flue checked within 12 months of installation and then at least every 12 months, keep the record, and give tenants a copy |
| 36A Date of the next check | A check made in the 2 months before the deadline date counts as made on it, so a landlord can bring forward a check and keep the same expiry date |
| 37 Escape of gas | The responsible person who knows or suspects gas is escaping must shut off the supply at once and notify the gas supplier if gas continues to escape or a smell persists |
Where is the detail for each regulation?
This page keeps the one-line summary, and the page that owns each fact is linked below by the regulation it covers. Regulation 9, the emergency control, has no page of its own on this site yet, and regulation 15's meter notice is covered only in the table above.
Regulation by regulation
Who do the regulations bind?
Different people hold different duties, which is why a single job can touch several regulations at once. The installer and the person working on a fitting carry Parts B, D and E. The landlord carries regulation 36. The responsible person for the premises, meaning the occupier, the owner or anyone with authority to act on a gas fitting, carries regulations 34 and 37.
What changed in the regulations, and are they still current?
The latest available version on legislation.gov.uk shows no known outstanding effects. HSE's L56, fifth edition, covers the Gas Safety (Installation and Use) (Amendment) Regulations 2018, in force on 6 April 2018, which added regulation 36A so a landlord can carry out the annual check in the two months before the due date and keep the existing expiry date. Two worked examples show how the table reads in practice.
- Worked example 1: an engineer replaces a boiler in a rented flat. Regulation 3 applies to who does the work, 22 and 33 to the tightness test and purge, 26(9) to the flue, combustion air, heat input and operation check afterwards, and 29 to leaving the maker's instructions. The landlord's regulation 36 duty then starts from the installation date, which is why the new record is kept.
- Worked example 2: a tenant's gas fire is suspected of spilling fumes while an engineer is on site for another job. Regulation 34(3) obliges the engineer to take reasonably practicable steps to inform the responsible person and, where different, the owner. The warning notice guide covers what classification follows.
Only a Gas Safe registered engineer can size, install, service or certify gas work, and a condensed line in a table is not a substitute for the regulation. HSE's L56 is the approved code of practice and guidance on how to meet them. Read the regulation and the guidance before relying on a wording.
If you smell gas or suspect carbon monoxide, turn the supply off, open windows and call National Gas on 0800 111 999, free, at any hour. Manifold records the regulation 36 detail on each gas safety certificate and reminds you before each landlord's deadline.
Frequently asked
Sources
- legislation.gov.uk, The Gas Safety (Installation and Use) Regulations 1998 (SI 1998 No. 2451), contents and full text
- HSE, Gas Safety (Installation and Use) Regulations 1998 as amended: Approved Code of Practice and guidance, L56 (fifth edition, 2018)
- Registered Gas Engineer, Industry Standard Update 135: Gas Safety (Installation and Use) (Amendment) Regulations (Northern Ireland) 2026
- National Gas, emergency contacts
Related guides
Last reviewed October 2026. This guide is general information, not legal or safety advice, gas safety work must be carried out by an appropriately Gas Safe registered engineer. Rules can change, so check the linked official sources for the current position.