Extending a leasehold house
If your house is leasehold, you have two separate hurdles, not one. You need planning permission the same as any other homeowner, and on top of that you need your freeholder's written consent — a licence to alter — because the lease almost certainly controls what you can do to the building. Sort the freeholder out early; it is the part people forget until their builder is ready to start.
The short answer
Most houses in England are freehold, so their owners never think about this. But a fair number of houses were sold on long leases — particularly newer estates in parts of the North West and the Midlands — and if yours is one of them, the lease is a contract that says what you may and may not do to the property. Nearly every long lease restricts structural alterations and extensions in some way.
So the order of play is: read the lease, approach the freeholder for consent, and run that alongside your planning application. Getting planning permission does not override the lease. You can have a signed grant of planning permission on the wall and still be in breach of contract if you build without the freeholder's sign-off.
What your lease actually says
Find the clause about alterations and improvements. It will fall into one of three types, and which one you have decides how much power the freeholder holds over you.
- Absolute covenant — the lease flatly bans the alteration. In theory the freeholder can refuse for any reason, or no reason. In practice you can still ask them to vary the lease or grant a one-off consent, but you are negotiating from the back foot and they can name their price.
- Qualified covenant — you may alter "with the landlord's consent". This is the common one.
- Fully qualified covenant — you may alter with consent, "such consent not to be unreasonably withheld". The best position to be in.
Here is the part worth knowing: even where your lease only gives you a qualified covenant, the law can upgrade it. Section 19(2) of the Landlord and Tenant Act 1927 reads into any lease that requires consent for improvements a proviso that the consent must not be unreasonably withheld — and an extension that adds space and value counts as an improvement. So for most extensions, a bare "with consent" clause behaves like a fully qualified one. That protection does not rescue an absolute covenant, though, which is why the distinction matters.
The licence to alter
Once you have the lease clause pinned down, the formal consent comes as a document called a licence to alter (sometimes a licence for alterations). It sets out exactly what you are allowed to build, usually references your drawings and specification, and lists any conditions the freeholder attaches. You should have it signed before a spade goes in the ground.
Expect to pay the freeholder's reasonable costs for granting it — that is their solicitor's fee and, on anything structural, a surveyor to review your plans. Those are your costs, not theirs, and the lease will say so. The professional fees, not any council charge, are the real expense here.
| Consent | Who grants it | Indicative cost | Can they refuse? |
|---|---|---|---|
| Freeholder's licence to alter | Your freeholder | Their legal + surveyor fees, often £1,000–£3,000 (more on bigger schemes), paid by you | Only reasonably, if the covenant is qualified or fully qualified |
| Planning permission (if not permitted development) | Local planning authority | £548 householder fee in England | Yes, on planning grounds |
| Building Regulations approval | Building control | Varies with the size of the job | Effectively no — it is about safety, not permission |
| Mortgage lender consent | Your lender | Usually free or a small admin fee | Rarely, but check your terms |
Householder planning fee is the England figure effective from 1 April 2026 (Planning Portal / GOV.UK). The "not unreasonably withheld" protection comes from section 19(2) of the Landlord and Tenant Act 1927 (legislation.gov.uk). Licence fees are typical market ranges, not a tariff — ask your freeholder for their basis in writing.
What a freeholder can reasonably ask for
When the covenant is qualified, "reasonable" is the whole ball game, and the burden sits on you to show a refusal is unreasonable. A freeholder is generally entitled to protect the value of their interest and the building itself. Conditions you might reasonably be asked to accept include supplying full structural drawings, using a competent contractor, making good any damage, keeping the works insured, and reinstating the alteration at the end of the term if they ask.
They can also seek compensation if the work genuinely reduces the value of their reversion, and they can recover their proper legal and professional costs. What they cannot do is sit on your application indefinitely or demand a fee out of all proportion to the work involved. If consent is being dragged out or refused on flimsy grounds, that is when specialist advice earns its keep — the case law on this is well developed.
Check what your lease actually includes
There is a trap here that catches people. Your lease demises a defined area, and it might not include everything you assume. Some house leases do not include the airspace above the roof, or a strip of the garden, or the subsoil. If you are planning a loft conversion into roof space you do not own, or an extension onto land outside the demise, consent to alter is not enough — you would need the freeholder to grant or sell you that extra land or airspace as well.
So before you commission drawings, get your conveyancer or a leasehold solicitor to confirm the extent of the demise against what you want to build. It is a cheap check that can save an expensive redesign.
Buying the freehold instead
If the freeholder is difficult, or you simply want to be rid of the question for good, the cleaner long-term answer is often to buy the freehold. Long leaseholders of houses have had the right to do this — enfranchisement — since the Leasehold Reform Act 1967, and it turns you into the outright owner, with no licence to alter to chase for this extension or any future one.
The rules have been loosening. Under the Leasehold and Freehold Reform Act 2024, the old requirement to have owned the property for two years before you could enfranchise was removed in January 2025, so you can start the process straight after buying. Some of the valuation reforms in that Act that would reduce the price you pay were still working through consultation and legal challenge through 2026, so the cost of buying a freehold can move — take current advice on the figure before you commit. If you are extending anyway and the lease is short or the ground rent onerous, it is worth pricing the freehold purchase alongside the licence to alter and deciding which route is better value over the years you will own the house.
Planning permission is still separate
None of the above replaces the ordinary planning and building rules. A leasehold house gets the same permitted development rights as a freehold one, so your extension may not need a planning application at all — but that is a question for your council, decided on the same limits as any other house. Start with the permitted development rules to see whether you need permission, and if a wall sits on or near a boundary, check whether you also need a party wall agreement. Those hurdles run in parallel with the freeholder's consent, not instead of it.
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