An increasing number of self build plots are known as ‘knock-downs’ — plots currently occupied by an existing dwelling that is, for one reason or another, not worth restoring or extending and therefore lends itself to demolition and replacement. The existing house might be poorly designed or too small for the size and value of the land it stands on, or simply beyond economic repair or improvement. Its fate will be further sealed by the fact that a new dwelling benefits from zero per cent VAT while renovation and extension work is usually standard rated at 20 per cent.

Before you decide whether to go down the demolition route, it’s worth considering a range of issues — from costs and VAT to environmental impact and planning rules.

How Much Does it Cost to Demolish

The cost of demolishing a house ranges from £6,000-£8,000 for a small detached property (80-120m2), up to £12,000-£15,000 for a more substantial property of 200-250m2. The bulk of this cost is disposal of the materials.

The cost will be mitigated if there are materials with salvage value. A contractor will list the value of any salvage items and usually offset this against the quote. A large part of the cost of demolition is landfill and haulage, so costs can be reduced if there is scope to reuse or dispose of non-toxic waste on site, such as clean hardcore for drives, paths, terraces and soakaways.

The time taken for demolition works depends on the scale and complexity of the house. The work will typically take four to eight working days. If the building is a semi-detached or terraced house, the adjoining buildings will require support following demolition, and this will add to the cost.

Asbestos

If there is specialist work required, such as removing asbestos (often found in the form of cladding, roofing, and rainwater goods), this can add to both the costs and schedule. There are strict rules on the removal and handling of asbestos, and it can be best to get a report and quote from a specialist contractor.

Existing service connections to electricity, mains water and sewage, and connection to the highway can usually be reused, and this can represent a significant saving compared to developing a virgin plot.

How to Qualify for Zero-Rated VAT

A new dwelling will qualify for zero-rated VAT providing it does not make use of any part of any existing dwelling, with the following exceptions:

  • a cellar/basement (you can also retain a ground floor slab);
  • retained party walls shared with neighbouring properties (for example, a terraced or semi-detached house);
  • one (two on a corner site) retained façade (only if it is required explicitly in your planning permission);
  • the creation of a new dwelling by adding another storey/ addition or conversion involving a change of use.

Detached garages or outbuildings can be retained. Demolition work itself can be zero-rated for VAT if it is undertaken in order to facilitate the construction of a new dwelling.

Environmental Impact

In a rural area, it is likely that a wildlife survey undertaken by an ecological consultant will be requested by the local planning authority, as part of the pre-application process for a replacement dwelling. If evidence of an endangered species is detected (typically bats, barn owls, badgers and greater crested newts), a further report will be required from a specialist before work can proceed.

The report will recommend the time of year that demolition work can take place, and the mitigation measures required, such as providing alternative habitats. Even where planning permission is not required for demolition, it is a criminal offence to harm or even disturb a protected species.

Demolition Method

The following order of works is typical for demolishing a house:

  • cut off and cap all services such as mains water and sewer connection, electricity, gas and telephone;
  • erect site fencing and protect the site;
  • erect scaffold if required;
  • hazardous material, such as asbestos, removed under licence or by specialists if necessary;
  • soft strip all loose items, kitchen and sanitaryware, and remove all cabling, lighting, plumbing, radiators, etc;
  • remove all doors, window frames, linings, internal/external timber mouldings, etc;
  • strip roof and lead flashings;
  • remove structural timbers, joists and trusses;
  • demolish walls and salvage bricks — unwanted material will be removed for crushing;
  • break up the remainder and grub up the foundations and redundant drains.

Planning and Other Rules

Demolition:

Planning permission is not normally required for demolition work, as it is classed as Permitted Development (PD). However, PD rights can be removed or restricted, in whole or in part, by the local authority using an Article 4 Direction (often used on listed buildings or in Conservation Areas) or an Article 3 Restriction (added as a condition of a planning approval for other works). In these instances, planning permission is required. 

Conservation Area Consent:

The substantial demolition of an unlisted building within a Conservation Area will require planning permission from the local authority, with the exception of buildings of less than 115m3, or walls or fences 1m high next to a highway, or 2m high elsewhere.

Listed Building Consent:

This consent is required for the demolition of any part of a listed building. Substantial demolition of a building within a Conservation Area, or of a listed building, without the relevant permission from the local planning authority is a criminal offence and could lead to potentially unlimited fines.

Replacement Dwelling Policy:

Planning policy usually allows a replacement dwelling, even in the open countryside, providing the building has not been abandoned. The definition of abandonment is not fully defined in law, so it is always best to get permission for a replacement dwelling prior to demolition.

Replacement dwelling policy varies across the UK, and in many areas there are restrictions on the scale of any enlargement, and its location, relative to the existing house. Where consent for a new dwelling in the open countryside has been granted on an exception – for example, conversion of a redundant agricultural building – total demolition of the existing building will invalidate the consent so this must be avoided. The same applies to agricultural dwellings.

Semis and Terraces:

If you are demolishing a property other than a detached house, it is likely that adjoining neighbouring properties enjoy a right of support — a special type of easement recognised and protected by law. When you undertake demolition works, you have a duty to support the remaining portions of the building and to ensure the new building continues to do so. The same right of support applies if you are excavating ground adjacent to a neighbour, for instance, for foundations or a new basement.

Party Walls:

If the demolition work affects a party wall or party wall structure, a party wall agreement will need to be negotiated under the terms of the Party Wall Act 1996 (England and Wales only).

Main image: iStock

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