Building Plan Approval Assistance · Question

Can I get approval for an extra floor on an existing building?

Short answer

Possibly, if the local rules still allow more built area on your plot and a structural engineer confirms the existing building can carry the addition. The authority decides, and it will look at the original approval, the permitted height and built-up area, and the safety of the structure. A refusal on either ground ends the idea, however good the design.

In more detail

Adding a floor is two separate questions, and both must be answered favourably.

Does the plot still have room to build?

Each area has rules on how much can be built on a plot, how tall a building may be and how far it must sit from boundaries. If the existing building already uses the permitted allowance, there may be nothing left to add. Rules also change over time, so the building may have been approved under an older regime. The authority will compare your proposal with the rules that apply now and with your earlier sanction.

Can the building carry it?

Foundations, columns and beams were designed for a certain use and number of storeys. A qualified structural engineer must examine drawings, if any survive, and test or inspect the structure to decide whether it can be strengthened or whether the addition is unsafe. Authorities commonly want this opinion on record, signed by a professional they recognise.

Original sanctioned drawings and completion or occupancy papers.
A structural report on the existing building.
Proposed drawings for the new floor, with any revised staircase, lift or fire arrangements.
Proof that the existing building is itself lawful and free of unresolved violations.

An unapproved base is a weak base

If the present building has unregularised deviations, the authority may ask for those to be resolved first. Adding a floor on top of them can compound the problem.

Where the existing structure cannot take more load, some owners explore lighter construction or a separate adjoining building instead. A structural professional can say which routes are realistic for your case.

Key points

Two tests apply together: allowed built area and structural capacity.
The authority compares your plan with current rules and the original sanction.
A signed structural report on the existing building is usually essential.
Existing violations may need to be resolved before new work is considered.
Lighter or separate construction may be an alternative if the structure cannot carry more.

Who this applies to

Owners of homes, shops or small factories wanting more floor space.
Landlords planning to add rentable area above an older building.
Buyers who learn that the seller promised a floor that was never approved.

Last reviewed 3 October 2026

This answer is general information, not advice on your particular case. Terms, eligibility, and requirements change, so check the current position with the relevant institution or authority.