Consultation Before Altering Your Home

Do I need planning permission to change the internal layout of my house?

In most cases, no. Internal alterations — removing walls, relocating a staircase, changing room layouts — do not require planning permission in the UK, as planning controls relate to external appearance and land use rather than internal arrangement. However, there are exceptions: if the property is listed, any alteration including internal changes requires Listed Building Consent before work begins. If you are converting part of a house into a separate self-contained flat, that is a change of use and does require planning permission. A 30-minute consultation will confirm whether your specific project needs any planning approval before you instruct a builder or architect.

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Does a loft conversion require planning permission, or is it covered by permitted development?

Most loft conversions in the UK fall under permitted development and do not require a planning application — provided they meet specific volume and design limits. In England, the permitted development allowance for a loft addition is 40 cubic metres for terraced houses and 50 cubic metres for detached and semi-detached houses. The addition must not exceed the height of the existing roof ridge, and any dormer facing a highway is not permitted. These allowances do not apply if the property is listed, if it is in a conservation area where an Article 4 Direction removes permitted development rights, or if previous alterations have already used up the permitted volume. Even where planning permission is not required, a building regulations application is always needed for a loft conversion — the structural alterations, stair access, fire escape, and insulation all require formal approval.​

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What building regulations apply when I remove a structural wall?

Removing a structural wall always requires building regulations approval, regardless of whether planning permission is needed. The regulations require that a structural engineer calculates the load being carried by the wall and specifies the correct beam size and bearing pad to replace it. A building control officer will inspect the work at key stages — before the beam goes in and after the wall is removed — and issue a completion certificate when the work is signed off. That certificate matters: it is required evidence when you sell the property that the work was carried out to the approved standard. Never remove a structural wall based on a builder's estimate of the beam size alone — if the calculation is wrong, the consequences are serious and the liability falls on you as the homeowner.

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How much does a typical house extension cost in the UK in 2026?

Extension costs vary considerably depending on size, specification, location, and the complexity of connecting the new structure to the existing building. As a general benchmark, a basic single-storey rear extension in the UK in 2026 starts at around £2,500 to £3,500 per square metre of internal floor area, including a standard specification finish. A larger or more complex extension — two storeys, side returns, a heavily glazed structure — will cost more. These figures are for construction only and do not include architect's fees, structural engineering, planning and building regulations applications, or VAT. VAT at 20% applies to most extension work on existing homes, although reduced rates apply in certain circumstances such as work on listed buildings. Allow a contingency of at least 15% on top of your build cost for unexpected items — particularly in older properties where what is behind walls and floors is often unknown until work begins.

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How long does the full process take from initial idea to a completed extension or alteration?

For a straightforward house extension, allow twelve to eighteen months from the first conversation with an architect to completion of construction. The stages are: feasibility and design (four to eight weeks), planning application if required (eight weeks statutory target, though two to four months in practice is more realistic for extensions), building regulations application (four to eight weeks), finding and appointing a builder and agreeing a contract (two to four months), and construction (three to six months for a typical single-storey extension). Projects that do not require planning permission — permitted development extensions, internal alterations — can move faster, but building regulations approval and contractor procurement still take several months. A consultation at the outset gives you a realistic programme for your specific project so you can plan around it rather than being surprised by the timescales later.