This is the single most important physical factor. The UT's key example of a building that is not a dwelling is "an empty shell with no main roof." A building that has lost its roof or whose walls have collapsed may have lost its identity as a dwelling.

However, a leaking roof or missing tiles are "dilapidation" — the building remains a dwelling. The question is whether the structural shell is fundamentally intact, not whether it is in good repair.

The UT held that defects must be assessed for whether they are "capable of remedy." If works cannot be carried out without prejudicing the structural integrity of the building (because, for instance, the walls might collapse), the building is unlikely to be suitable for use as a dwelling.

In Mudan itself, Mr Mudan agreed there was "no structural damage to the Property and no structural work was required except to replace the missing roof over the boiler room" — the property remained a dwelling despite needing complete renovation.

Mere "dilapidation" — cracks, settlement, subsidence that can be underpinned — does not destroy dwelling identity.

The UT in Ridgway held that suitability may involve "a wide range of factors, including the physical attributes of the building but also any restrictions on use of the building, including legal restrictions." The Court of Appeal cited this with approval.

A legal prohibition on use — such as a Closure Order, Dangerous Structure Notice, or planning restriction preventing residential occupation — may be relevant alongside the physical condition, depending on its terms. The FTT in Fish Homes (a First-tier Tribunal decision, which is not binding) noted that hazards which "would spur a local authority to issue a prohibition notice" are relevant.

However, a mere improvement notice does not prevent use as a dwelling.

The Court of Appeal cited Lord Carnwath's judgment in Day v Hosebay, which distinguished between a building that was "disused and dilapidated" (still a house — Boss Holdings) and one where "the residential use has not merely ceased, but has been wholly replaced by a new, non-residential use" (no longer a house — Hosebay).

If the building has been physically converted so that its residential identity has been replaced by a commercial or other non-residential identity, it may no longer be a dwelling. But mere disuse or dilapidation does not cause loss of identity.

The UT held that defects must be assessed for whether they are "capable of remedy." It specifically noted that works which would be "so dangerous or hazardous as to prejudice their viability" mean the building is unlikely to remain suitable.

Bewley (a First-tier Tribunal decision, which is not binding) is the leading example: the FTT found the bungalow was not suitable for use as a dwelling because asbestos contamination prevented any repairs or alterations from being carried out safely. The presence of the asbestos made the building incapable of repair, not merely in need of repair.

Fire damage that destroys the structure may have the same effect. But smoke damage or repairable fire damage does not stop a building being a dwelling.

In Mudan, the property needed complete rewiring and a new boiler — the Court of Appeal upheld the finding that it remained a dwelling. The UT held at para 54(5) that unsafe occupation "for instance, because the building requires rewiring" is a relevant factor but "would not of itself render the building unsuitable for use as a dwelling."

The Court of Appeal also noted (para 62) that property which is actually occupied is residential regardless of condition — meaning a property with dangerous electrics that someone is actually living in is self-evidently a dwelling. The test cannot logically produce a different result simply because the occupant has moved out.

These are repairable defects. They are relevant, but not enough on their own to show that the building had lost its identity as a dwelling.

Damp and mould, even if severe, are "dilapidation." Under the Mudan framework, these are works needed to render a building "habitable" — which is expressly distinguished from works that affect dwelling identity.

The only exception: if rot or damp has caused the structure to physically collapse (e.g., rotten joists causing floor collapse), the structural damage itself may be relevant — but that is scored under "Structural Integrity" above, not here.

These are repairable defects. They are relevant, but not enough on their own to show that the building had lost its identity as a dwelling.

The Court of Appeal cited Boss Holdings, where the House of Lords held that a building "disused and in part stripped back to the basic shell" remained a house because it had not lost its identity. Lord Neuberger said: "The fact that the property had become internally dilapidated and incapable of beneficial occupation (without the installation of floor boards, plastering, rewiring, replumbing and the like) does not detract from the fact that the property was designed for living in."

In Mudan itself, the property had broken windows, broken doors, missing locks, and was full of rubbish inside and out — the FTT found it remained a dwelling.

Abandonment and vandalism are relevant, but not enough on their own. If they have caused structural collapse, score that under Structural Integrity above.