Air conditioning in a flat is entirely possible, and we fit it regularly. But a leasehold flat comes with a document that matters as much as any building regulation: your lease. It sets out what you own, what the freeholder owns and what you need permission to change.
This guide is general information to help you prepare, not legal advice. For your own situation, read your lease carefully and speak to a solicitor or your managing agent.
Why leaseholders usually need consent
GOV.UK’s guide to leaseholder rights and responsibilities says your lease will tell you what conditions you’ve agreed to, including whether you need permission to make alterations. In many leases:
- the external walls, roof and structure belong to the freeholder, not the flat owner;
- making holes through external walls is an alteration that needs consent;
- fixing anything to the outside of the building, such as an outdoor unit or trunking, is restricted;
- balconies, terraces and gardens may be demised to you, shared, or kept by the freeholder.
Some leases prohibit certain alterations outright. Others say consent is needed but can’t be unreasonably withheld. Small differences in wording make a big difference, which is why you start with the lease itself.
What to check in your lease
- The demise: exactly which parts of the building are included in your flat.
- Alterations clause: whether structural or external alterations are allowed, with or without consent.
- Nuisance clause: anything about noise or annoyance to other residents.
- Use of common parts: whether pipework can run through shared areas.
- Regulations or house rules: some blocks have separate rules about external fixtures.
If you don’t have a copy, your solicitor will have one from your purchase, or you can usually get one from HM Land Registry.
How to ask the freeholder
Contact the freeholder or their managing agent in writing. A request is far more likely to be approved quickly if it includes:
- where the indoor and outdoor units will go, with photos or a sketch;
- the pipe route and the size of any holes through walls;
- manufacturer details for the units, including published sound levels;
- how condensate will drain;
- the installer’s details and accreditations: we are F-Gas certified and NICEIC approved.
We can give you a survey report with this information to send on. Expect the freeholder to have their own requirements on position, noise and appearance.
Want it done properly? AirCon Doctor installs, repairs and services air conditioning and heat pumps across London and the South East, from our base in East Grinstead. We’re an F-Gas certified company and NICEIC approved. Get a fixed-price quote.
Licence for alterations
Where consent is given, it is often recorded in a formal document, commonly called a licence for alterations. It typically sets out what you may do, conditions about how the work is done and maintained, and who is responsible for any damage or later removal. The freeholder may ask you to pay their legal and surveyor costs. These costs vary, so ask for an estimate at the start. Don’t start work until the licence is signed. If you are buying a flat that already has air conditioning, your solicitor should check that consent was obtained.
Talk to your neighbours too
Even with consent in place, the people most affected by an outdoor unit are often the flats next door and below. Sharing your plans early, showing them where the unit will sit and explaining the published sound levels of the model tends to prevent complaints later. Many leases include a clause about nuisance to other occupiers, so a well-placed, well-mounted unit protects you as well as them. Regular servicing keeps fans and mounts quiet over the years.
Planning still applies
Consent from the freeholder doesn’t replace planning rules. On the Planning Portal, permitted development for heat pumps on flats and blocks of flats has different limits from houses (0.6 m³ for the outdoor unit), and cooling-only units aren’t covered at all. Conservation areas and listed buildings add further restrictions. Check both the lease and the planning position. Our planning permission guide explains the basics.
Options when an outdoor unit isn’t possible
If consent for an external unit is refused, you may still have options. An outdoor unit on a balcony or terrace that forms part of your demise may be acceptable. A unit placed in a communal plant area may be possible with the freeholder’s agreement. Our guide to air conditioning for flats covers these, and what to avoid.
Quick answers
Do I need permission to install air conditioning in a leasehold flat?
Usually, yes, because the work affects external walls or common parts. Your lease sets out exactly what consent is needed.
What is a licence for alterations?
A formal document in which the freeholder gives consent to specific works, usually with conditions. It is often prepared by the freeholder’s solicitor.
Can the freeholder refuse?
It depends on the lease wording. Some leases prohibit certain alterations; others require consent not to be unreasonably withheld. Take legal advice if a refusal seems unreasonable.
Does freeholder consent mean I don’t need planning permission?
No. Planning rules and the lease are separate. You may need both.
Related services
More advice
- Air Conditioning for Apartments and Flats: Complete Guide
- Do I Need Planning Permission for Air Conditioning in the UK?
- Where to Put an Air Conditioning Outdoor Unit
- What Happens at an Air Conditioning Site Survey
- All advice
This guide is general information, checked against the sources linked on 30 October 2026. It isn’t legal, tax or financial advice. Rules, grants and product ranges change, so check the current position before you rely on it.