What to expect
| Typical duration | Assessment weeks · the process itself months |
|---|---|
| Cost band | Figures live in the cost index |
| Permit required | Resolves the position so a permit can proceed |
| Seasonal constraint | Not seasonal |
What we typically find
This is not an exotic problem. On property that has been in the same family for decades, some version of it is close to normal.
- A room added at some point, frequently on a terrace or in a courtyard.
- A terrace enclosed and turned into living space.
- A store, stable or agricultural building converted to habitable use.
- A cave or basement extended.
- A pool built without permission.
- A retaining wall or terracing above the height that would have required approval.
- An additional floor, or a roof terrace enclosed.
- Changes to openings in a designated settlement without settlement approval.
Why it matters even if you like the extra room
- It blocks a new permit. You cannot get approval for new work on a property with an unresolved unauthorised structure. This is where most owners discover it.
- It complicates a sale. A buyer's lawyer will find it, and the transaction either stalls or the price moves.
- It affects licensing. Operating as tourist accommodation with an unauthorised structure is a problem. See tourist accommodation licence.
- It affects insurance. An unauthorised structure may not be covered, which matters most in exactly the situation you would want cover.
- It can affect the mortgage or financing on the property.
How the process works
Legalisation is a legal process carried out by a registered engineer, not by a contractor. Broadly:
- A registered engineer surveys and documents what actually exists against what is permitted.
- The nature of each unauthorised element is categorised — this determines whether and how it can be regularised.
- Where it can be regularised, the declaration is made and the applicable fees paid.
- Where it cannot, the options are removal, or modification to something that can be permitted.
- The position is then clear, and a new permit application can proceed.
What cannot be resolved
Not everything can be regularised, and it is better to hear that plainly.
- Structures in locations where building is not permitted at all.
- Work in protected settings that is fundamentally incompatible with the designation.
- Structures that are unsafe, which is a separate problem from being unauthorised.
- Anything encroaching on a neighbour's property or on public land, which is an ownership question first.
Where removal is the answer, that is demolition work — and on a property with no vehicle access, removing an unauthorised structure is a genuine haulage job. See demolition.
What this covers
We do not carry out legalisations; that is your engineer's work. Our part is practical and it comes before and after:
- Before: on a purchase survey, comparing what is built against what is permitted, and telling you plainly when something does not match. This is one of the highest-value findings a pre-purchase survey produces.
- During: coordinating so the legalisation and the new design proceed together rather than sequentially, where that is possible.
- After: carrying out any removal or modification required, and building the new work once the position is clear.
Questions people actually ask
I am buying a property with an unauthorised extension. Should I walk away?
Not necessarily. It is a known and priceable issue. What matters is establishing before you commit whether it can be regularised, what that costs, and how long it takes — because it will hold up any build programme you were planning.
Can I just leave it and not mention it?
It will surface — at sale, at licensing, at insurance, or the first time you apply for a permit. Leaving it means the problem arrives at a moment you did not choose.
How much does legalisation cost?
It depends on the nature and size of the unauthorised element and on the current framework, and your engineer will assess it. Treat it as a specific budget line rather than a contingency.
How long does it take?
Months rather than weeks, and it depends on the complexity. Start it as soon as you know about it, because it sits on the critical path of everything else.
Can I get a permit for new work while legalisation is in progress?
Generally the position needs resolving first. Your engineer will advise on your specific situation, and the practical planning assumption should be that it is sequential.