Glossary

The Building Safety Act runs on defined terms, and getting them wrong is how projects get the regime wrong. 108 of them, in plain English, each written the way a practitioner would explain it on site.

A

A2-s1,d0: The reaction-to-fire classification, under EN 13501-1, generally required alongside A1 for materials that become part of an external wall of a relevant building over 18m since the 2018 combustibles ban: limited combustibility with minimal smoke production and no flaming droplets.
Accountable Person: The organisation or person who owns or has a repairing obligation for the common parts of an occupied higher-risk building. Accountable persons must assess and manage building safety risks, principally fire spread and structural failure, on an ongoing basis. Where a building has several, one is designated the principal accountable person.See also: Principal Accountable Person (PAP), Higher-Risk Building, Safety Case Report
Approval with Requirements: One of three possible Gateway 2 outcomes, alongside full approval and rejection. The Building Safety Regulator approves the application but attaches requirements, typically to provide further information or resolve specified matters before or as the relevant work proceeds. Each requirement must then be discharged as the build progresses.See also: Gateway 2, Building Control Approval, Building Safety Regulator (BSR)
Approved Document B: The statutory guidance on fire safety under the Building Regulations for England, covering means of escape, fire spread, structure and access for firefighting. Amendments to it carry major regime changes, including the second staircase provisions for new residential buildings over 18m.
As-built information: Plans and documents that record what was actually constructed, not what was designed. A valid Gateway 3 application must include as-built information reflecting the finished building. Discrepancies between as-built drawings and the systems or materials actually installed are one of the Building Safety Regulator's named reasons Gateway 3 applications stall.See also: Gateway 3, Golden Thread, Compliance Declaration
Associated Company: A company connected to a landlord or developer through the Act's association tests, including group and control relationships. Remediation contribution orders can reach associated companies, which is why special purpose vehicle structures have not shielded development groups from remediation costs.

B

Batching: A Building Safety Regulator process, piloted between September and December 2025, in which groups of Gateway 2 applications are bundled and assessed by external specialist assessors under BSR oversight. Batching helped clear the new-build backlog and delivered median determination times of 12-14 weeks, with some approvals inside the statutory 12.See also: Gateway 2, Innovation Unit, Building Safety Regulator (BSR)
BS 9991: The British Standard code of practice for fire safety in the design, management and use of residential buildings, revised in 2024. It is a primary reference for residential fire strategy, and alignment with the current edition is a recurring expectation in Gateway 2 review. BSI publishes it; this site describes it only.
Build to Rent: Residential development built for institutional renting rather than individual sale, commonly abbreviated BTR. Funder milestones and lease-up schedules make BTR schemes acutely sensitive to gateway timing, and several prominent early Gateway 2 approvals and applications have been BTR towers.
Build UK: The contractor and supply chain trade body whose Gateway Two and Gateway Three guides, published in 2025, set out validation requirements, portal mechanics and practical recommendations, including giving the BSR at least 8 weeks notice of intent to apply at Gateway 3.
Building a Safer Future: Dame Judith Hackitt's May 2018 final report from the Independent Review of Building Regulations and Fire Safety. It diagnosed a race to the bottom and recommended the architecture the Act built: gateways, dutyholders, a golden thread of information and a single regulator for higher-risk buildings.
Building Assessment Certificate (BAC): A certificate issued by the Building Safety Regulator confirming that the accountable persons for an occupied higher-risk building are meeting their occupation-phase duties. The principal accountable person applies when directed by the regulator, submitting the safety case report and evidence of resident engagement and mandatory occurrence reporting systems.See also: Principal Accountable Person (PAP), Safety Case Report, Resident Engagement Strategy
Building Control Approval: The Building Safety Regulator's formal approval of a Gateway 2 application, granted as the building control authority for higher-risk buildings in England. Construction cannot lawfully start without it. Outcomes are approval, approval with requirements, or rejection, and dutyholders must give the BSR five working days notice before starting work.See also: Gateway 2, Approval with Requirements, Building Safety Regulator (BSR)
Building Control Authority: The body legally responsible for building control on a project. For every higher-risk building in England that authority is the Building Safety Regulator; local authorities and registered building control approvers cover buildings outside the higher-risk regime.
Building Regulations Compliance Statement: A Gateway 2 application document explaining how the proposed design complies with each applicable requirement of the Building Regulations, including where compliance relies on guidance, testing or engineered solutions. It gives the regulator a route map through the design information and is one of the documents CLC guidance now templates.See also: Gateway 2, Construction Control Plan, Fire and Emergency File
Building Safety Act 2022: The primary legislation, given Royal Assent on 28 April 2022, that rebuilt building regulation in England after Grenfell. It creates the Building Safety Regulator, the gateway regime for higher-risk buildings, the dutyholder and competence framework, the golden thread requirement, occupation-phase duties and the Part 5 leaseholder protections.
Building Safety Case: The body of evidence an accountable person holds to show that building safety risks in an occupied higher-risk building, principally fire spread and structural failure, have been identified and are being managed so far as reasonably practicable. It is summarised for the regulator in the safety case report.See also: Safety Case Report, Accountable Person, Building Assessment Certificate (BAC)
Building Safety Levy: A levy on new residential development in England, in force from 1 October 2026, that funds the remediation of historical building safety defects. It bites at building control: the Building Safety Regulator will not issue a Gateway 3 completion certificate where levy payment is overdue, so unpaid levy blocks occupation.See also: Gateway 3, Gateway 2
Building Safety Regulator (BSR): The regulator created by the Building Safety Act 2022 to oversee higher-risk buildings in England. It has been the building control authority for all HRBs since 1 October 2023, running Gateways 2 and 3, and became a standalone public body sponsored by MHCLG on 27 January 2026.See also: Gateway 2, Gateway 3, MHCLG

C

Cavity Barrier: A component installed in concealed cavities, most critically behind rainscreen cladding, to close the cavity and resist the spread of fire and smoke. Correct specification and installation of cavity barriers, evidenced by photographs taken before closing up, is among the most scrutinised details in the regime.
CDM Regulations: The Construction (Design and Management) Regulations 2015, which manage health and safety in construction through client, principal designer and principal contractor roles. The Building Safety Act deliberately mirrors that structure in Part 2A, attaching building regulations compliance duties to the same named roles.
Change Control Log: The record of every controlled change made to a higher-risk building project between Gateway 2 approval and Gateway 3, capturing what changed, why, its compliance impact and who authorised it. Weak change control records are one of the Building Safety Regulator's four named reasons Gateway 3 applications stall.See also: Controlled Change, Major Change, Notifiable Change
CLC Guidance Notes: The Construction Leadership Council's suite of higher-risk building guidance, first published with the BSR in July 2025 and since updated, covering application project briefs, information schedules, folder structures and compliance statements. It has become the de facto submission standard; read it at the CLC, not here.
Client (BSA): The dutyholder for whom higher-risk building work is carried out. Under Part 2A of the Building Regulations the client must make suitable arrangements for compliance, appoint a principal designer and principal contractor, and sign the client statement submitted with the Gateway 2 application accepting its dutyholder obligations.See also: Dutyholder, Principal Designer (BSA), Principal Contractor (BSA)
Commissioning Evidence: The records proving that safety systems, alarms, smoke control, sprinklers, dampers and their integration with each other, were tested and perform as designed. Missing or incomplete commissioning evidence is one of the BSR's four named reasons Gateway 3 applications stall.
Compartmentation: The division of a building into fire-resisting compartments so fire and smoke are contained where they start. Walls, floors, doors, dampers and firestopping form the system together; a single unsealed penetration compromises it, which is why the regime is obsessive about installation evidence.
Competence Declaration: A signed declaration, submitted with a Gateway 2 application, in which the client confirms that appointed dutyholders have the skills, knowledge, experience and behaviours, or organisational capability, that their roles demand. It puts competence on the record before construction and is a standing requirement of the dutyholder regime.See also: Dutyholder, Client (BSA), Gateway 2
Completion Certificate: The certificate the BSR issues at Gateway 3 confirming that notifiable building work on a higher-risk building complies with building regulations. It is a hard stop: occupying the building before the certificate is issued and the building registered is a criminal offence.
Compliance Declaration: A signed declaration required at Gateway 3 in which the principal designer and principal contractor each confirm that, to the best of their knowledge, the completed work complies with Building Regulations. It attaches personal professional accountability to the completion certificate application and cannot sensibly be signed without evidence.See also: Gateway 3, Principal Designer (BSA), Principal Contractor (BSA)
Construction Control Plan: A Gateway 2 application document setting out how compliance will be managed during construction: site supervision arrangements, inspection and test regimes, competence management, change control procedures and how the golden thread will be kept current. The Building Safety Regulator assesses whether the plan is credible before approving a start on site.See also: Gateway 2, Golden Thread, Controlled Change
Construction Products Reform: The government programme, continuing through 2026, to reform how construction products are tested, certified and marketed, carrying the Grenfell Inquiry's findings about product testing and marketing practices toward new legislation.
Contemporaneous Records: Records made at the time of the work by people in a position to know, dated and attributable: site diaries, photographs of work before covering up, inspection results, delivery records. They carry evidential weight that retrospective reconstruction cannot, and completion assessment runs on them.
Controlled Change: Any change to an approved higher-risk building design between Gateways 2 and 3 that must pass through the change control process. Controlled changes split into major changes, which need Building Safety Regulator approval before the affected work proceeds, and notifiable changes, which proceed unless the regulator objects within 14 days.See also: Major Change, Notifiable Change, Change Control Log
Curtain Walling: A non-loadbearing external wall system, typically aluminium framing with glazed and infill panels, hung from the building's structure. CWCT standards govern its specification and testing in the UK, and its interfaces with floors and cavity barriers are safety-critical details the regime examines.

D

Determination: The substantive decision on a building control application: whether the design demonstrates compliance with building regulations. Statutory determination periods run 12 weeks for new-build Gateway 2 applications, 8 weeks for work to existing higher-risk buildings, and 8 weeks at Gateway 3 from a valid application.
Dutyholder: Any of the roles carrying legal duties for building regulations compliance under Part 2A of the Building Regulations, in force since 1 October 2023: the client, principal designer, principal contractor, and every designer and contractor. Each must be competent for its role and cooperate to plan, manage and monitor compliance.See also: Client (BSA), Principal Designer (BSA), Principal Contractor (BSA)

E

EN 13501-1: The European classification standard for reaction to fire of construction products, producing classes from A1 and A2 (limited or no combustibility) downward. Classification reports to EN 13501-1 are core golden thread evidence, and they apply to specific tested configurations rather than to products in the abstract.
External Wall System: The complete build-up of an external wall: outer facing, insulation, membranes, cavity barriers, fixings and substrate, considered as one system. Fire performance belongs to the system as tested, not to individual products, which is why substitutions demand freshly checked evidence.

F

Fast Track Process: The delivery mechanism introduced in the June 2025 BSR reset to accelerate the backlog of Gateway 2 applications, running alongside the Innovation Unit and the batching model as part of the recovery that cut the legacy queue to low single figures by spring 2026.
Final Inspection: The site inspection the BSR must arrange before determining a Gateway 3 application, checking the built work and its records against the approved design. Discrepancies between records and reality found at final inspection are a leading reason completion certificate applications stall.
Fire and Emergency File: A Gateway 2 application document capturing the fire safety information for a higher-risk building: the fire strategy, the systems provided and the assumptions the design relies on. It is maintained through construction, forms part of the golden thread, and is handed to the accountable person for the occupation phase.See also: Gateway 2, Golden Thread, Fire Statement
Fire Risk Assessment: The assessment of fire risks the responsible person must make, record and keep current under the Fire Safety Order. In higher-risk buildings it operates alongside, and feeds into, the accountable person's safety case for the building as a whole.
Fire Safety Order: The Regulatory Reform (Fire Safety) Order 2005, the fire safety regime for the non-domestic and common parts of buildings in England and Wales, enforced mainly by fire and rescue services. It runs alongside the Building Safety Act regime and was amended by section 156.
Fire Statement: The fire safety document submitted with a planning application at Planning Gateway One, required since August 2021 for relevant high-rise residential buildings. It sets out fire safety considerations at a level appropriate to planning, such as site access for fire appliances, and is reviewed by the regulator as statutory consultee.See also: Planning Gateway One, Gateway 1, Relevant Building
Firestopping: The sealing of gaps and service penetrations through fire-resisting walls and floors so that compartmentation actually works. Tested details matched to the actual penetration, installed by competent installers and recorded before covering up, are the evidence Gateway 3 assessment expects to see.
First-tier Tribunal: The tribunal, through its Property Chamber, that decides most Building Safety Act disputes in England: applications for remediation orders and remediation contribution orders, leaseholder protection disputes, and appeals against Building Safety Regulator decisions. For practitioners it is where the Act's civil enforcement teeth are actually applied.See also: Remediation Order, Remediation Contribution Order, Qualifying Lease

G

Gateway 1: The planning-stage checkpoint of the higher-risk regime, live since August 2021. A fire statement must accompany the planning application for relevant high-rise residential buildings, with the regulator acting as statutory consultee on fire safety. Hospitals and care homes are excluded at this stage despite being HRBs at Gateways 2 and 3.See also: Planning Gateway One, Fire Statement, Gateway 2
Gateway 2: The hard stop before construction of a higher-risk building. Building control approval must be obtained from the Building Safety Regulator before work can lawfully start. Statutory determination is 12 weeks for new builds and 8 weeks for work to existing HRBs; fees are 195 pounds plus 156 pounds per hour per assessor.See also: Building Control Approval, Gateway 3, Staged Application
Gateway 3: The hard stop before occupation of a higher-risk building. A completion certificate application goes to the Building Safety Regulator once notifiable work is complete; statutory determination is 8 weeks and fees are 189 pounds plus 151 pounds per hour. Occupying before the certificate is issued and the building registered is a criminal offence.See also: Gateway 2, As-built information, Partial Completion Certificate
Golden Thread: The digital, accurate and accessible record of a higher-risk building's design, construction and safety information, created at Gateway 2, maintained through every change during the build, and handed to the accountable person at Gateway 3. It exists so anyone managing the building can understand it and keep it safe.See also: Gateway 3, As-built information, Accountable Person
Grenfell Tower Inquiry: The public inquiry into the 14 June 2017 Grenfell Tower fire, in which 72 people died. Its Phase 2 report, published 4 September 2024, examined how the building came to be wrapped in combustible materials and recommended a single construction regulator under one government department.

H

Hackitt Review: Dame Judith Hackitt's Independent Review of Building Regulations and Fire Safety, commissioned after Grenfell. Its May 2018 final report, Building a Safer Future, found a race to the bottom in building standards and recommended the gateways, dutyholder accountability, the golden thread and a single regulator that became the Building Safety Act 2022.See also: Golden Thread, Dutyholder, Building Safety Regulator (BSR)
Higher-Risk Building: In England, a building at least 18 metres tall or with at least 7 storeys, containing at least two residential units. Hospitals and care homes meeting the height threshold are higher-risk buildings at design and construction stage. HRBs are subject to Gateways 2 and 3 and BSR building control.See also: Gateway 2, Gateway 3, HRB Register
Higher-Risk Buildings Procedures Regulations 2023: The Building (Higher-Risk Buildings Procedures) (England) Regulations 2023, the statutory instrument that operates the gateway regime: building control approval applications, determination periods, change control categories, completion certificate applications and the procedural machinery the BSR administers for higher-risk buildings.
HRB Register: The Building Safety Regulator's register of occupied higher-risk buildings in England. Existing HRBs had to be registered by 30 September 2023; new buildings must be registered by the principal accountable person before occupation. For new HRBs, occupation without both registration and a Gateway 3 completion certificate is a criminal offence.See also: Principal Accountable Person (PAP), Higher-Risk Building, Gateway 3

I

Innovation Unit: A Building Safety Regulator unit created in the June 2025 reforms to process new-build Gateway 2 applications. In the 12 weeks to 1 August 2026, the BSR decided 45 new-build and conversion applications, approving 91%, with a median determination time of 22 weeks.See also: Gateway 2, Batching, Building Safety Regulator (BSR)
Inspection and Test Plan: The quality plan listing the inspections and tests each element of work must pass, who witnesses them and what records result. Signed, dated ITP records for safety-critical work form a backbone of the contemporaneous evidence that Gateway 3 assessment relies on.

J

Joint Code of Practice: The Fire Prevention on Construction Sites code, commonly called the JCoP, published by the Fire Protection Association and required by most insurers on larger projects. It governs fire safety during construction itself, complementing the regime's focus on the completed building.

K

Key Building Information: Structured information about an occupied higher-risk building that the principal accountable person must submit to the Building Safety Regulator after registration and keep up to date: matters such as structure, materials, fire safety provisions and use. It gives the regulator a risk profile of the occupied HRB stock.See also: Principal Accountable Person (PAP), HRB Register, Higher-Risk Building

L

Landlord Certificate: The certificate a landlord of a relevant building must provide to leaseholders setting out whether the landlord, or an associated company, is responsible for relevant historical safety defects and whether it meets the Act's contribution conditions. It determines what remediation costs, if any, can be passed to qualifying leaseholders.See also: Qualifying Lease, Leaseholder Deed of Certificate, Relevant Building
LEASE: The Leasehold Advisory Service: the government-funded advice body giving leaseholders free initial guidance on their rights, including the Building Safety Act protections, the certificate machinery, service charge disputes and applications to the First-tier Tribunal.
Leaseholder Deed of Certificate: The certificate a leaseholder in a relevant building completes to evidence whether their lease is a qualifying lease under the Building Safety Act's leaseholder protections. It records the position at the qualifying time and feeds the landlord certificate process that decides how remediation costs can lawfully be apportioned.See also: Qualifying Lease, Landlord Certificate, Relevant Building

M

Major Change: A controlled change significant enough to require Building Safety Regulator approval before the affected work can proceed, typically taking 4-6 weeks, with work on the affected area stopped in the meantime. Major changes are the heavyweight tier of change control between Gateways 2 and 3 and must be fully evidenced.See also: Controlled Change, Notifiable Change, Change Control Log
Mandatory Occurrence Reporting: The system dutyholders and accountable persons must operate to report safety occurrences on higher-risk buildings to the Building Safety Regulator: incidents or risks that could cause death or serious injury from fire spread or structural failure. A mandatory occurrence reporting plan is a required part of every Gateway 2 application.See also: Gateway 2, Dutyholder, Building Safety Regulator (BSR)
MHCLG: The Ministry of Housing, Communities and Local Government, the department that owns building safety policy in England. Since 27 January 2026 it has sponsored the Building Safety Regulator as a standalone public body, a step toward the single construction regulator recommended by the Grenfell Inquiry Phase 2 report.See also: Building Safety Regulator (BSR)
Multi-Disciplinary Team (MDT): The assessment model for higher-risk building applications: registered building inspectors working with fire and structural specialists so a submission is reviewed across disciplines. Batching extends the model by bundling applications out to external specialist assessors working under BSR oversight.

N

Non-determination: The position when a statutory determination period expires without a decision. The regime treats the application as undetermined rather than approved: there is no default approval for higher-risk buildings, which is why realistic programmes plan on the regulator's actual timescales rather than the statutory clock alone.
Notifiable Change: A controlled change that must be notified to the Building Safety Regulator but can proceed unless the regulator objects within 14 days. Less serious than a major change, it still has to be recorded in the change control log with its compliance justification, because weak change records stall Gateway 3 applications.See also: Controlled Change, Major Change, Change Control Log

O

Occupation Gap: The period between finishing construction and lawful occupation of a higher-risk building: the Gateway 3 application, its 8-week determination, final inspection and registration. Who carries its cost, developer or contractor, is one of the sharpest negotiation points in HRB contracts.
Organisational Capability: The organisational limb of the competence test: a company accepting a dutyholder appointment must have the systems, resources and collective competence to discharge it, not merely employ capable individuals. It is what competence declarations assert at organisational level.

P

Part 2A (Building Regulations): The part of the Building Regulations, in force since 1 October 2023, that creates the dutyholder and competence regime for all building work: clients, principal designers, principal contractors and the duties each owes to plan, manage and monitor compliance with building regulations.
Part 4 (Building Safety Act): The part of the Act governing occupied higher-risk buildings: registration, the accountable person and principal accountable person, safety case reports, building assessment certificates, resident engagement and mandatory occurrence reporting. It is the regime a building lives under after Gateway 3.
Part 5 (Building Safety Act): The part of the Act containing the leaseholder protections and remediation machinery for existing buildings: qualifying leases, the service charge protections in Schedule 8, landlord and leaseholder certificates, and the remediation orders and contribution orders made at the First-tier Tribunal.
Partial Completion Certificate: A Gateway 3 completion certificate covering part of a higher-risk building, allowing that part to be occupied while work continues elsewhere. It is only available where a partial completion strategy was agreed with the Building Safety Regulator at Gateway 2, and it is not generally suitable for individual flats or floors.See also: Gateway 3, Gateway 2, Staged Application
PAS 8671: The BSI specification for the competence of principal designers discharging the Part 2A duty: the fire safety, regulatory and information management knowledge, and the behaviours, expected of the role on building regulations compliance, with enhanced expectations where the project is a higher-risk building.
PAS 8672: The BSI specification for the competence of principal contractors under Part 2A: what the role must know and demonstrate about planning, managing and monitoring construction-phase compliance with building regulations, again with enhanced expectations on higher-risk buildings.
PAS 8673: The BSI specification for the competence of those managing building safety in occupied higher-risk buildings: the knowledge, skills and behaviours expected of building safety management carried out on behalf of accountable persons under the Part 4 regime.
Planning Gateway One: The formal name for Gateway 1, in force since August 2021. Fire statements accompany planning applications for relevant high-rise residential buildings, and the Health and Safety Executive acts as statutory consultee on fire safety to the local planning authority. It front-loads fire thinking before land deals harden the design.See also: Gateway 1, Fire Statement
Practical Completion: The building contract milestone at which works are certified complete enough for handover. On higher-risk buildings it no longer permits occupation: the Gateway 3 completion certificate and registration stand between practical completion and residents, creating the occupation gap contracts now allocate.
Pre-application Engagement: Structured discussion with the BSR before a gateway application is submitted, used to settle routing, scope and contentious points before the statutory clock starts. Applicants who engage early and then submit fully resolved designs are the consistent pattern behind the fastest approvals.
Principal Accountable Person (PAP): Where an occupied higher-risk building has more than one accountable person, the one responsible for the structure and exterior. The PAP registers the building, submits key building information, prepares the safety case report and resident engagement strategy, and applies for the building assessment certificate when directed by the regulator.See also: Accountable Person, HRB Register, Safety Case Report
Principal Contractor (BSA): The dutyholder in control of the construction phase of higher-risk building work under Part 2A of the Building Regulations. Distinct in law from the CDM principal contractor, though usually the same firm, it must plan, manage and monitor compliance on site and sign the Gateway 3 compliance declaration.See also: Dutyholder, Principal Designer (BSA), Compliance Declaration
Principal Designer (BSA): The dutyholder in control of the design phase of higher-risk building work under Part 2A of the Building Regulations. It must plan, manage and monitor design work so the design, if built, would comply with Building Regulations, and it signs the compliance declaration submitted at Gateway 3.See also: Dutyholder, Principal Contractor (BSA), Compliance Declaration
Purpose-Built Student Accommodation: Student housing built as such, commonly abbreviated PBSA. Its towers are frequently higher-risk buildings, and its fixed academic-year deadlines make gateway timescales commercially brutal: missing September means losing a year, which is why PBSA developers lead demand for staged applications.

Q

Qualifying Lease: A long lease of a single dwelling in a relevant building that met the Building Safety Act's conditions at the qualifying time, including the property being the leaseholder's principal home or one of a limited number of owned properties. Qualifying leaseholders receive statutory protections limiting historical safety remediation costs.See also: Relevant Building, Landlord Certificate, Leaseholder Deed of Certificate

R

Rainscreen Cladding: An external wall build-up in which an outer panel screens a drained and ventilated cavity over insulation and the structural wall. It is the configuration at the centre of the cladding crisis, and the one whose materials, cavity barriers and test evidence receive the sharpest gateway scrutiny.
Registered Building Inspector (RBI): A building control professional registered with the Building Safety Regulator, the qualification required to carry out restricted building control work in England. On higher-risk buildings, RBIs work within the BSR's multi-disciplinary teams alongside fire and structural specialists rather than acting as the standalone approver of the old regime.See also: Building Safety Regulator (BSR), Higher-Risk Building
Regularisation: The building control route for seeking retrospective approval of unauthorised work. For higher-risk buildings the message is blunt: work carried out outside the gateway regime has no easy retrospective fix, and the only sound strategy is never to create the problem.
Relevant Building: A term the Building Safety Act uses in two contexts. At Planning Gateway One it means the high-rise residential buildings needing a fire statement. In the Part 5 leaseholder protections it means residential buildings above a lower height threshold than higher-risk buildings, whose qualifying leaseholders are protected from historical remediation costs.See also: Qualifying Lease, Higher-Risk Building, Planning Gateway One
Relevant Defect: A defect arising from work done in the 30 years before the protections commenced that causes a building safety risk in a relevant building. The concept anchors Part 5: the leaseholder protections and the tribunal's remediation orders both operate by reference to relevant defects.
Remediation Contribution Order: A First-tier Tribunal order requiring a landlord, developer or associated company to contribute to the costs of remedying relevant defects in a relevant building. It lets interested parties, including leaseholders and regulators, pursue the parties who caused or profited from defects rather than those who merely live with them.See also: Remediation Order, First-tier Tribunal, Relevant Building
Remediation Improvement Plan: The government plan launched in April 2026 to accelerate the remediation of unsafe buildings, addressing the gap between the legal tools available, orders, contribution orders and funding schemes, and the actual pace at which affected buildings were being fixed.
Remediation Order: A First-tier Tribunal order requiring a relevant landlord to remedy specified relevant defects in a relevant building within a set time. It is the direct enforcement route for getting unsafe buildings fixed, and can be sought by leaseholders, regulators and other interested persons under the Building Safety Act.See also: Remediation Contribution Order, First-tier Tribunal, Relevant Building
Resident Engagement Strategy: The strategy a principal accountable person must prepare for an occupied higher-risk building setting out how residents will be given building safety information, consulted on decisions that affect them, and able to raise concerns and complaints. It is assessed as part of the building assessment certificate process.See also: Principal Accountable Person (PAP), Building Assessment Certificate (BAC), Accountable Person
RIBA Stage 4: The technical design stage of the RIBA Plan of Work, at which the design is developed to construction-level detail. Front-loading design to Stage 4 or beyond before a Gateway 2 submission has become standard practice for higher-risk buildings, because the BSR expects a fully resolved, evidenced design.

S

Safety Case Report: The document summarising an occupied higher-risk building's safety case: the building safety risks identified, principally fire spread and structural failure, and the evidence that they are being managed. The principal accountable person produces it and submits it to the Building Safety Regulator when applying for a building assessment certificate.See also: Building Safety Case, Principal Accountable Person (PAP), Building Assessment Certificate (BAC)
Safety Occurrence: A structural or fire safety incident or risk serious enough to threaten life, triggering the mandatory occurrence reporting duty: prompt notification to the BSR with a fuller report to follow, made through the reporting system the project's Gateway 2 plan describes.
Schedule 8: The schedule of the Building Safety Act that limits what qualifying leaseholders can be charged for historical safety defects: cladding system remediation cannot be passed on at all, other defect costs are capped, and developer-linked landlords cannot recover contributions from qualifying leaseholders.
Second Staircase Mandate: The requirement that all new residential buildings in England above 18 metres include a second staircase, in force from 30 September 2026 with transitional provisions for sufficiently progressed schemes. Designs already in the Gateway 2 pipeline have had to be checked, and in some cases reworked, against it.See also: Gateway 2, Higher-Risk Building
Section 156: The section of the Building Safety Act that amended the Regulatory Reform (Fire Safety) Order 2005 from 1 October 2023, strengthening fire risk assessment record-keeping, cooperation and coordination between responsible persons, and the fire safety information residents must be given.
Single Construction Regulator: The Grenfell Inquiry Phase 2 recommendation for one regulator consolidating construction oversight under one department. The BSR's move out of the HSE to become a standalone body under MHCLG on 27 January 2026 is the visible structural step in that direction.
Skills, Knowledge, Experience and Behaviours: The four-limbed test of individual competence under the Building Safety Act regime, often abbreviated SKEB. Behaviours is the limb that encodes culture: technical excellence does not make a person competent if they will sign what the programme wants rather than what the evidence supports.
Staged Application: A Gateway 2 application made in stages, letting groundworks and substructure be approved and started before the superstructure design is signed off. Originally for complex multi-building schemes, staged applications were extended to single-tower higher-risk buildings in December 2025 and are now a standard programme-protection tactic for developers.See also: Gateway 2, Building Control Approval
Statutory Consultee: A body that planning or building control authorities must consult before deciding. At Planning Gateway One the regulator is statutory consultee on fire safety to the local planning authority for relevant high-rise residential applications, and its advice shapes what Gateway 2 later expects.
Stop Notice: An enforcement notice from the Building Safety Regulator requiring work on a higher-risk building to stop until specified serious non-compliance is put right. Breaching a stop notice is a criminal offence. It sits alongside compliance notices and prosecution in the regulator's enforcement toolkit for gateway and building regulations breaches.See also: Building Safety Regulator (BSR), Gateway 2, Gateway 3

T

Transitional Provisions: The rules deciding which regime applies to schemes already in progress when requirements change, such as those protecting sufficiently progressed schemes from the 30 September 2026 second staircase mandate. Reading them precisely against programme dates is specialist work with large consequences.

V

Validation: The completeness check an application passes before substantive assessment begins: are the required documents present, organised and usable. Applications that fail validation are returned without a decision, and validation failures are among the most avoidable causes of lost programme time at Gateway 2.

W

Waking Watch: Continuous fire patrols posted in a building with known fire safety defects so occupants can be alerted and evacuated, used as an interim measure where alarms or compartmentation cannot yet be relied on. Its notorious cost to leaseholders drove parts of the remediation reform agenda.