Core Drilling Permits and Regulations: UK Guide

Most core drilling in the UK is straightforward from a regulatory perspective: a service penetration through an external brick wall for a boiler flue or waste pipe does not require planning permission and is unlikely to trigger Building Regulations notification. But there are important exceptions — and the consequences of missing one can be significant.

Listed building consent, CDM 2015 duties on commercial projects, fire stopping requirements under Part B, and Party Wall Act obligations are the categories most commonly overlooked by trade professionals. This guide sets out what applies and when.

Does Core Drilling Require Planning Permission?

For standard service penetrations — boiler flue, extractor fan, waste pipe, cable entry — planning permission is not required. These fall within permitted development under Schedule 2 of the Town and Country Planning (General Permitted Development) (England) Order 2015, and under equivalent legislation in Scotland, Wales, and Northern Ireland.

Planning permission may be required in the following circumstances:

• Listed buildings — any alteration requires listed building consent (administered by the local planning authority, but a separate consent from planning permission). See below.
• Conservation areas — some external alterations in conservation areas require prior approval, though internal service penetrations through external walls are generally permitted. Check with the local planning authority if the penetration is visible from a public highway.
• Flats and leasehold properties — drilling a ventilation or flue penetration through an external wall may require freeholder consent under the terms of the lease, independent of planning requirements.

When Does Core Drilling Require a Building Regulations Application?

Building Regulations apply to the installation that the penetration is for, not to the act of drilling itself. Whether a notification or application is needed depends on what the hole is for and where it is:

Part A — Structure

Any penetration through a load-bearing structural element — a structural concrete wall, a load-bearing masonry wall, or a structural floor slab — must not compromise the structural integrity of that element. Where structural drawings are unavailable and the element's load-bearing function is uncertain, a structural engineer should confirm the proposed penetration is acceptable before drilling. Building control notification is not routinely required for individual service penetrations, but unauthorised alteration of a structural element is a regulatory offence under Building Regulation A1. See: core drilling through concrete: UK contractor's guide.

Part F — Ventilation

Part F of the Building Regulations governs ventilation in new and altered buildings. When drilling is carried out for a boiler flue or mechanical ventilation system, the installation (not the drilling) must comply with Part F requirements. This typically falls to the installer — a Gas Safe registered engineer for boiler flues, or a ventilation contractor for HVAC systems. The driller's responsibility is to provide the correctly sized hole at the specified position. See: boiler flue core drill size guide.

Part B — Fire Safety and Compartmentation

Part B requires that fire compartment barriers — walls, floors, and ceilings separating fire compartments — maintain their integrity. Where a core drill penetrates a compartment wall or floor, the annular gap around the pipe, duct, or cable must be fire stopped to restore the compartment barrier. This applies in domestic houses (where each storey is typically a separate fire compartment) and in commercial buildings where compartmentation requirements are more stringent.

Building Notice vs Full Plans Application

For notifiable domestic building work, a building notice submitted to local authority building control before work starts is typically sufficient. A full plans application is required for commercial and large-scale projects, and for certain structural alterations. For most trade drilling on domestic sites, the responsibility for Building Regulations compliance rests with the engineer or contractor managing the installation — the boiler engineer, plumber, or HVAC contractor — not the driller.

What Fire Stopping Is Required After Core Drilling?

When a core drill penetrates a compartment wall or floor, the annular gap must be sealed with a fire-rated product to restore the fire barrier. This is one of the most commonly missed post-drilling obligations. The correct product depends on what passes through the hole:

• Plastic pipes (waste, soil, gas) — an intumescent collar or wrap is required around the pipe where it passes through the compartment barrier. In a fire, the intumescent material expands to fill the gap as the plastic pipe burns away, maintaining compartmentation.
• Metal pipes and ducts — fire-rated sealant (to BS EN 1366-3 or equivalent) applied around the annular gap restores the barrier. The gap between the duct and the wall opening must be packed and sealed.
• Cables — fire-rated intumescent pillows, putty pads, or proprietary cable transit systems are used to seal cable penetrations through compartment barriers.
• Boiler flues — Building Regulations Part J requires the gap between the flue and the wall opening to be sealed with fire-rated intumescent sealant or a proprietary flue sealing plate. The Gas Safe engineer completing the installation is responsible for confirming Part J compliance.

Where uncertainty exists about whether a wall or floor is a compartment barrier, treat it as one and fire stop accordingly. See: diamond core drill safety guide.

Does Drilling a Listed Building Require Consent?

Any alteration to a listed building — including drilling a service penetration through a wall or floor — requires listed building consent (LBC) from the local planning authority before work begins. This applies to:

• Grade I listed buildings (highest protection)
• Grade II* (Grade two star) listed buildings
• Grade II listed buildings (the most common category, covering approximately 91% of all listed buildings in England)
• Category A, B, and C(S) listed buildings in Scotland
• Grade I and II listed buildings in Wales

Listed building consent is required for both external and internal alterations. A boiler flue penetration through the external wall of a listed building — even a minor Grade II property — requires LBC before work starts. Carrying out works without consent is a criminal offence under the Planning (Listed Buildings and Conservation Areas) Act 1990, carrying a fine or up to two years' imprisonment.

The practical implication for contractors: confirm listed building status before drilling on older properties, particularly Georgian, Victorian, and Edwardian buildings in conservation areas. Local authority planning portals and the National Heritage List for England (NHLE) are searchable online. Contact the relevant local planning authority before accepting or starting any drilling work on a listed building.

CDM 2015 — When Does It Apply to Core Drilling?

The Construction (Design and Management) Regulations 2015 (CDM 2015) apply to virtually all construction work in the UK. However, the specific duties depend on whether the project is notifiable.

Notifiable Projects

A project is notifiable under CDM 2015 if it exceeds either of these thresholds:

• 30 working days with more than 20 workers simultaneously on site; or
• 500 person-days of construction work in total

For most trade drilling — a plumber coring a boiler flue, an electrician drilling cable entries on a domestic job — the project is not notifiable. Standard COSHH and health and safety obligations apply. See: dust extraction for core drilling and silica dust control in construction.

On notifiable projects, CDM 2015 requires:

• The client to appoint a Principal Designer and Principal Contractor
• An F10 notification submitted to HSE before the construction phase begins
• A pre-construction health and safety plan addressing significant hazards — including pre-drill scanning and structural confirmation for load-bearing concrete elements
• A health and safety file maintained and handed to the client on completion

On notifiable commercial projects, drilling into structural concrete must be addressed in the pre-construction health and safety plan. Pre-drill GPR scanning is part of this duty where post-tensioning cannot be ruled out. See: GPR scanning before core drilling.

Domestic Client Exception

Where the client is a domestic homeowner not carrying out work in connection with a business, the domestic client exception under CDM 2015 applies. The contractor takes on the client's CDM duties. For small domestic drilling jobs, this means the contractor remains responsible for safe working practices, COSHH compliance, and dust control — but the full commercial CDM duty structure (Principal Designer appointment, F10 notification, pre-construction H&S plan) does not apply.

Party Wall Act 1996 — When Does Drilling Through a Party Wall Apply?

The Party Wall etc. Act 1996 applies to work to a party structure — walls, floors, and other elements shared between two separate properties. Core drilling that penetrates a party wall (the shared wall between two terraced or semi-detached properties) may trigger Party Wall Act obligations.

Scenarios where the Act commonly applies to drilling:

• 110mm soil stack through a party wall — drilling a 117mm hole through a party wall to run a soil pipe into a shared void is a penetration of the party structure. A party wall notice should be served on the adjoining owner before work begins. This is the scenario most commonly encountered by plumbers and builders.
• Cable or pipe entries through a party wall — where the hole passes through (not just up to) the party wall, or notches the party structure, the Act applies.

The Party Wall Act process: serve a party wall notice on the adjoining owner at least two months before starting work on the party structure. If the adjoining owner consents in writing within 14 days, work can proceed. If they do not respond or dissent, both parties appoint a party wall surveyor to draw up an award. Failure to serve notice does not make the work unlawful, but removes the statutory protections the Act provides and exposes the building owner to claims for any damage.

For most single-wall service penetrations — a boiler flue or extractor fan through the property's own external wall — the Party Wall Act does not apply. It is relevant primarily where the hole passes through a shared party wall rather than the property's sole external masonry.

Permits and Regulations: Common Questions