A lease can restrict changing the boiler system or drilling through an external wall for a flue. Where the lease requires it, the Leasehold Advisory Service says written consent must be obtained before work starts, even where planning or building regulations approval exists.
In this guide
A boiler swap in a leasehold flat can involve more than the installer and the householder, because the flue, pipework or chimney may belong to the freeholder. This guide summarises the Leasehold Advisory Service (LEASE), the government-funded body that advises leaseholders in England and Wales, in its guides on alterations and on repairs and maintenance, both reviewed in December 2025. It is general information, not advice on a specific lease, which a solicitor should read.
Why a boiler change can need consent
LEASE says that depending on the terms of the lease, a leaseholder may need the landlord’s permission before making alterations, even where planning permission or building regulations approval has been obtained. It lists safety-critical work such as changes affecting gas pipes among the alterations that may need a landlord’s agreement, and its examples of common lease restrictions include “changing the boiler system” and “drilling into the external wall to install a flue”. Another typical clause bans cutting external walls, which would prevent new openings for pipes.
Demised and retained parts of the building
LEASE explains that the lease may also ban work affecting parts the landlord owns or controls, called the “retained premises”, while the parts the leaseholder owns and controls are the “demised premises”. Its examples include external walls, shared floors or ceilings (where underfloor heating might pass through another flat), and chimneys or flues, where a leaseholder wants to install a wood-burning stove. A flue that must pass through an external wall or use a shared chimney can therefore fall into the retained category.
Responsibility for the boiler itself is a separate question. LEASE says leaseholders are usually responsible for repairs inside the flat, including pipes and wiring that only serve it even if partly outside, while the landlord is usually responsible for the roof, external walls and shared facilities such as lifts or boilers, and for pipes and wiring serving the whole building. The lease governs, and where a communal boiler is replaced the consultation process described in the guide to shared boiler plant and Section 20 may apply.
How to ask for consent
If the lease requires written permission, LEASE says it must be obtained before the work starts, and it may be needed each time. Verbal consent should not be relied on. The request should be in writing and dated, with copies kept, and LEASE suggests including:
- a clear description of the work;
- plans or photos;
- contractor quotes and insurance details;
- proof of building regulation compliance or planning permission, or the applications for them; and
- a proposed timetable and contact details.
The lease may say how much notice to give and how long the landlord has to reply. If it does not, LEASE says the landlord can be asked to respond by a certain date, although it does not have to meet that deadline, and a reasonable period such as two weeks should be allowed. The planning and building regulation side is covered in the guides to planning permission for a flue and building regulations notification.
If consent is refused or the lease bans the work
Where the lease allows alterations with consent, LEASE says the landlord must respond in writing, give consent unless there is a reasonable reason to refuse, and state reasons for any refusal. That does not apply if the alterations involve a part of the building the landlord owns or controls. If the lease bans alterations, the landlord does not have to consider the request or reply, and the clause would need to be varied. Because a new flue can touch an external wall, it is worth checking early whether the work falls within the retained premises.
Fees and premiums
LEASE says that if the lease allows, a landlord can charge for legal or other expenses of giving consent, such as a surveyor or an inspection of the finished work, and these are administration charges that must be reasonable and accompanied by a summary of the leaseholder’s rights. It is against the law to charge a premium for non-structural alterations needing consent. If the work affects parts the landlord owns, a premium may be possible, usually a share of the value the alteration adds, with no legal limit and no tribunal challenge.
Working without consent
LEASE states that an alteration made without required permission can breach the lease, even where a previous owner made it, because restrictions run with the land. Unauthorised alterations can make the property harder to sell, remortgage or insure, and LEASE suggests seeking professional advice about retrospective consent. Buyers of a flat with an existing flue or system change may wish to check whether consent was given.
FAQs
Does planning permission replace the freeholder’s consent?
No. LEASE says that even with planning permission or building regulations approval, the landlord’s consent is still needed where the lease requires it.
Can a freeholder charge for giving consent?
If the lease permits, yes, but LEASE says the fee is an administration charge that must be reasonable. A premium is unlawful for non-structural alterations needing consent.
Who is responsible for a communal boiler?
LEASE says the landlord is usually responsible for shared facilities such as boilers, with costs recovered through the service charge, but the lease is what counts.
The bottom line
In a leasehold flat in England or Wales, a new flue, a change to the heating system or work touching external walls or shared parts may need the freeholder’s written consent before any work begins, whatever planning or building regulations approval exists. A clear written request, with plans, quotes and insurance, a reasonable time for a reply and no work until permission arrives, protects against breach of the lease and problems at sale. A solicitor can read the specific lease. This is general information, not personalised advice.
Sources
This guide draws on the following primary sources, current as of 9 October 2026:
- Leasehold Advisory Service, Alterations and home improvements, reviewed 22 December 2025 (lease-advice.org)
- Leasehold Advisory Service, Repairs and maintenance in leasehold properties, reviewed 16 December 2025 (lease-advice.org)
- Leasehold Advisory Service, About us (lease-advice.org)
Related guides
Shared boiler plant in flats
Planning permission for a flue
Building regulations notification
Best Boiler Deals is an independent guide. We may earn a fee from some links; this never affects what we write. This article is general information, not regulated advice on any specific installation; always confirm the details with a Gas Safe registered engineer.