property & types
Penthouse
A penthouse is an apartment on the top floor of a block, usually marketed as larger and more premium than the other flats. It is a marketing word, not a legal category, so it says nothing about how the flat is owned.
In simple terms
A penthouse is a top-floor flat marketed as premium. It is usually leasehold, so the lease and charges matter more than the label.
Example
A fourth-floor penthouse in a purpose-built block has a private lift lobby and a roof terrace. It is sold leasehold, so the buyer's solicitor reads the lease to see who maintains the terrace, who is responsible for the roof above, and how the flat's share of the service charge is worked out.
If you're buying
Because penthouse is a marketing word, treat it as a prompt to read the paperwork. One reference describes penthouses as often the largest and most expensive apartments in a building, and says they may span more than one level. GOV.UK says most flats are leasehold, so you own the property for a fixed term and the lease sets your costs and duties. Ask for the lease length, ground rent, service charge accounts and any planned major works, because a larger flat can carry a larger share of building costs. Check who is responsible for the roof, terrace, lift and any plant above you, and whether the lease restricts alterations or subletting. Compare the asking price with sold prices for similar top-floor flats in the same block, not just the street. (Sources read 30 October 2026: Designing Buildings penthouse entry, which is not UK specific; GOV.UK leasehold property and service charges.)
If you're selling
Call it a penthouse only if the flat genuinely is on the top floor, and be ready to show what makes it different. Buyers will want the lease, the service charge breakdown, building insurance and details of any roof or terrace responsibilities. Gather them early so the sale is not held up. If recent major works or a service charge dispute exists, tell your solicitor at the start.