Across Cornwall, plenty of homeowners own a house that's in the right place but is the wrong building: a tired 1960s bungalow on a great plot, a cold, poorly built chalet, or a property that would cost more to put right than to replace. In these cases, knocking down the existing house and building a new one, known in planning terms as a replacement dwelling, can be the best long-term option. This guide explains how replacement dwellings typically work in Cornwall, from planning and demolition to Building Regulations and tax, so you can decide whether it's the right route for you.
Renovate, extend or replace?
Before committing to demolition, it's worth comparing the options honestly. Replacement often makes sense when:
The existing house has serious structural, damp or construction problems.
Its layout, ceiling heights or orientation make a good renovation difficult.
Bringing it up to modern energy standards would mean replacing most of the fabric anyway.
The plot could take a better-designed home that makes more of the views, light and garden.
On the other hand, a sound older property, particularly one with character, may be better suited to renovation or extension. Our guides to bungalow renovation in Cornwall and home extensions cover those routes. A builder or quantity surveyor can help compare likely costs before you spend heavily on design.
Planning permission for a replacement dwelling
Demolishing a house and building a new one will normally need full planning permission from Cornwall Council. While every site is assessed on its merits, councils typically consider:
Whether there's a lawful existing home. A replacement usually relies on the existing building being a lawful dwelling that hasn't been abandoned. Derelict ruins or buildings with a different lawful use are usually treated differently.
Size and scale. Councils often look at how the new home compares with the existing one, especially in the countryside, and a substantially larger building may face closer scrutiny.
Siting. A replacement on or close to the footprint of the existing house is often viewed differently from one moved to a new part of the plot.
Design and materials. The new home will normally be expected to suit its surroundings, particularly in a conservation area or the Cornwall National Landscape.
Neighbours and landscape. Overlooking, height, light and visual impact all form part of the assessment.
Our guides to planning permission in Cornwall and building in an AONB or conservation area explain the wider process. Pre-application advice from the council can be useful before detailed drawings are prepared.
Surveys and reports you may need
A replacement dwelling application is often supported by several reports. Depending on the site, these can include:
Ecology surveys, especially for bats, which commonly roost in older roofs. Bat surveys are seasonal, so it's worth arranging them early.
Biodiversity net gain information, which applies to many planning applications in England, subject to exemptions.
Drainage and percolation tests, particularly for rural homes on septic tanks or treatment plants.
Topographical and tree surveys where levels or trees affect the design.
Flood risk assessments for sites in or near flood zones.
Demolition: what's involved
Taking down a house is more than just bringing in a digger. Typical steps include:
An asbestos survey before demolition, as many homes built before 2000 contain asbestos that must be identified and removed safely.
Disconnecting services such as electricity, water, gas and telecoms, which can take time to arrange with suppliers.
Notifying the council about demolition where required, and agreeing any conditions on the planning permission.
Managing waste, including separating materials and reusing or recycling where practical. Crushed masonry can sometimes be reused on site.
Protecting neighbours from dust and noise, and agreeing safe access for plant and lorries.
Demolition then leads straight into site preparation and groundworks and foundations for the new home. Our article on groundworks and foundations in Cornwall explains this stage.
Building Regulations for the new home
A replacement dwelling is a new home, so it must meet the Building Regulations in full. That includes structure, fire safety, energy efficiency, ventilation, overheating, water efficiency, accessibility and electric vehicle charging. Energy standards for new homes are significantly higher than those for older housing, which is one reason a well-built replacement can be much warmer and cheaper to run. In radon-affected parts of Cornwall, protection measures will usually be needed. Our guide to Building Regulations in Cornwall covers how approval works, and if you're interested in low-energy design, see our article on eco home building in Cornwall.
VAT, CIL and other costs
Tax and levies can make a real difference to a replacement project, so take advice early:
VAT. The construction of a new dwelling can qualify for zero-rating, and there's a scheme that may let individuals building their own home reclaim some VAT. Whether a replacement qualifies depends on strict conditions, including how much of the existing building is demolished. Rules change, so check the current position with HMRC guidance or an accountant before work starts.
Community Infrastructure Levy (CIL). Cornwall Council charges CIL on some new development. Exemptions or relief may be available, for example for self-builders, and existing floorspace can sometimes be taken into account. Any claims usually need to be made before work begins.
Warranties. Mortgage lenders often expect a new home to have a structural warranty or professional supervision certificate, so arrange this before construction starts.
Managing the project
A replacement dwelling involves designers, surveyors, Building Control, utilities and many trades, as well as a period when you'll need to live elsewhere. Clear specification, realistic programming and cost control make a big difference. Our project management and QS services can help keep things on track, and our new builds in Cornwall page explains how we approach new homes. If you're also weighing up a plot elsewhere, our self-build homes guide is a useful companion read.
Replacement dwelling FAQs
Can I make my replacement home bigger than the existing house?
Often some increase is possible, but how much depends on the site, its setting and Cornwall Council's policies. In the countryside and protected landscapes, size is usually looked at carefully, so it's worth getting advice early.
Do I need permission just to demolish my house?
Demolition of a house can require prior approval or planning permission, and in a conservation area permission is normally needed. When demolition forms part of a replacement scheme, it's usually dealt with in the same planning application.
How long does a replacement dwelling take?
It varies with design, planning, surveys and the size of the build. Planning and pre-construction work can take many months, and construction itself commonly runs for most of a year or more for a typical family home.
Talk to us about your replacement home
If you're considering knocking down and rebuilding a house anywhere in Cornwall, we can help you understand the practical steps and plan the build. Call us on 01208 816991 or contact us to talk through your plans.
