Renovate or build a brand new home?

If demolishing your house and building a replacement makes more sense than renovating, use the advice of industry experts to decide if it’s the best option for you

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When is it the best option to build a new home?

When you’ve found a run-down property (via a website such as, it’s important to weigh up whether renovating or rebuilding is the right option, as Hugo Tugman, founder of Architect Your Home and Interior Your Home, explains.

‘The most common reasons to keep the existing building and renovate are:

  • If it has architectural charm or merit to be preserved. It is impossible to truly reproduce the authenticity of genuinely old buildings and it’s often important to try to keep the building’s fabric, both for exterior character and interior features.
  • Even if a building is going to be changed radically, very often there are cost advantages to keeping the most basic fabric in place, rather than starting again with new footings, external walls etc.
  • It can be a lot easier to get planning approval for alterations to an existing building (often possible under permitted development) than to get permission for a new house. This is not always the case but, in many, will be the path of least resistance.
  • From a “green” perspective, retaining and reusing things that already exist is generally seen as requiring less energy than demolishing and building from scratch.

The most common reasons to knock down your home and rebuild are:

  • Modifications to an existing building are generally subject to full VAT, while new-build projects are zero rated for VAT, so it often makes financial sense to start again.
  • From a “green” perspective, while the process of knocking down and rebuilding might require more energy than retaining and reusing, if the existing building fabric cannot be upgraded effectively, the long-term energy losses of retaining it can outweigh the short-term energy use in a rebuild.
  • Many people will feel much more comfortable with something newly built, knowing that it is entirely sturdy, where the services run and so forth. In addition, anomalies such as over-steep staircases and narrow doorways can be avoided.’

What’s the process when building a new home?

If demolition followed by construction of a new house is on the agenda, don’t tackle the project in two halves. ‘Combine your applications for demolition and replacement in one, both for planning and building regulations,’ says chartered surveyor Ian Rock, author of the Haynes Self-Build Manual and director of survey price comparison site,

‘Once the old building’s gone, there’s technically no obligation on the planners to grant consent since there’s now nothing to replace. Although in most cases you would get permission, you can’t be certain.

‘Councils normally limit the size of replacement dwellings to a percentage increase over the original building. When it comes to negotiating an uplift in size, it may sometimes be possible to exceed the council’s size policy on the grounds that the existing property could have been bigger had the owner chosen to extend it by utilising permitted development rights.’

If you live in a rural area, the local planning authority is likely to request that an ecological consultant undertake a wildlife survey as part of the pre-application process for the replacement dwelling, explains experienced home renovator Michael Holmes. ‘If evidence of endangered species is detected (typically bats, barn owls, badgers and great crested newts), a further report will be required from a specialist before work can proceed.’

Demolition permission

‘Classed as permitted development, in some cases you will not need to apply for planning permission to knock down a building, e.g. for smaller residential buildings of up to 50 cubic metres (measured externally, including the walls),’ explains Ian Rock. However, the local council may have removed or restricted these rights, and it’s essential to check.

‘There are draconian penalties for unlawful demolition, including the requirement to fully reinstate the original building at your own expense. Listed buildings are rigorously protected (listed building consent is only very rarely granted for demolition). Similarly, properties in Conservation Areas cannot be demolished without prior consent.

‘Before you unleash the wrecking ball, you also need to apply for a formal decision on whether the council planners want to approve the details of how you intend to carry out the demolition and restore the site afterwards.

‘When it comes to building regulations, you normally need to give six weeks’ prior written notice to building control. Demolition can only commence once the local authority has issued a counter notice, which they also send to adjoining owners and occupiers, as well as to the relevant gas, electric, water and drainage suppliers.’

Contractors’ role

Knocking down an old house is a specialist job. ‘It’s also a legal minefield strewn with health and safety legislation, in most cases requiring prior notification to local authority building control,’ says Ian Rock. ‘There may also be potential risks from hazardous materials, such as asbestos, as well as possible issues with the support and protection of adjoining structures (hence the Party Wall Act may also come into play).

‘Because demolition counts as construction work, it will normally need to comply with the construction, design and management (CDM) regulations. The person nominated as duty holder is legally required to prepare a health and safety plan highlighting the main risks. The main contractor must then notify the Health and Safety Executive and ensure that all persons they employ to carry out demolition work do so in accordance with this.’

New foundations

‘Where a building is demolished to make way for a new one, the new foundations can be cut through the old ones, provided there are no deep cellars,’ says Ian. ‘But new foundations usually need to be considerably deeper, so you can’t simply build on top of the existing ones.

‘A new suspended ground floor can bridge over any areas of backfill and rubble left below ground. At worst, large areas of backfill could mean using more expensive foundations, such as rafts. More worrying is the risk of potential contamination from former industrial use. Your new house design will need to comply with Part C of the building regulations, relating to site preparation and resistance to contaminants. The building control counter notice will also normally specify a range of precautionary measures regarding adjacent buildings.

A new build near York

‘The eco credentials of our new build reduce the running costs significantly’


Multiple problems meant replacement was the right strategy for the owners of this house near York. The original property had a low floor level, making it prone to dampness; the low-lying landscape produced a flood threat in periods of heavy and prolonged rain; and the roof timbers were undersized. The internal layout of the house was also impractical, with staircases leading to different parts of the first floor; one was narrow and steep, too, which made it hard to get furniture upstairs.

The heating system was inadequate, while the electrics needed replacing. Although the original windows had previously been exchanged for uPVC versions, they were of poor quality and deteriorating, and didn’t provide a means of escape in case of fire. The bathroom and kitchen were also tired.

‘So much money needed to be spent that a replacement dwelling was a far better option,’ explains architect Stephen Samuel, of Samuel Kendall Associates.

The owners wanted a new house as large as planning rules would allow, and so the architect designed a three-storey, seven-bedroom replacement, lifted around a metre out of the ground to minimise the danger of flooding.

With the architects managing the entire project, demolition took place over three weeks, and building the new house took a year. ‘All the principal reception rooms are on the southern side of the house to maximise direct solar gain, and the service rooms on the northern side,’ explains Stephen, of the eco design.

brick house rebuild with red clay tile roof

Using bricks from the old house to reduce the carbon footprint of the new build, along with its passive solar design, makes this a very energy- efficient home

The walls were constructed using brick recycled from the old house, and a ground-source heat pump draws heat from the land, feeding the underfloor heating and hot water. The house has mechanical ventilation, with 95 per cent heat recovery in an airtight design and, externally, heat loss is minimised by the materials used. Rooflights allow light to penetrate the ground floor via the staircase shaft and, together with large windows concentrated on the eastern, southern and western sides of the house, reduce the need for artificial light. The composite windows are energy efficient, and all the doors are double sealed.

‘Because of the eco approach taken, the running costs are less than 20 per cent of those of a similar dwelling without the invested eco credentials,’ says Stephen.

A similar house of this type and specification would cost around £1,020 to £1,240 per square metre.

How much does it cost?

‘The cost of demolishing whole structures is generally based on their volume – a rough guide price might be around £30 to £40 per cubic metre,’ says Ian. ‘But costs will be skewed by factors such as ease of access, façade retention or work involving asbestos.

‘Money spent on knocking things down can sometimes be reduced by salvaging any valuable architectural materials, such as fire surrounds and slates. You may also be able to recycle rubble as hardcore for new driveways etc. Ready-connected sewers, drains and services can save a small fortune, along with existing driveways, gardens and fencing. You may also be able to utilise the old house as temporary accommodation.’

With the new house, it can make use of some parts of the previous dwelling and still qualify for zero-rate VAT, explains Michael Holmes. These are: a cellar or basement – although it must be demolished to the top of basement/cellar walls; party walls shared with neighbouring properties; and a retained façade required by listing or Conservation Area status. Detached garages or outbuildings can also be retained. 

Which features should your new home include?

You’ll need to adhere to more exacting requirements for the replacement house than would be the case if you’d renovated. ‘One difference is that every aspect of a new house must comply fully with building regulations,’ explains Hugo Tugman. ‘As well as being structurally sound and meeting certain standards on insulation, it must also involve requirements such as disabled toilet facilities at entrance level, or maximum stair gradients. With an existing dwelling, there’s no need to upgrade existing non-compliant features of the building as long as the proposed works will not make their non-compliance worse.’

Eco features are also well worth incorporating. ‘Underfloor heating costs more to install than radiators, but because it operates at lower temperatures and is more energy efficient, running costs are lower,’ says Ian Rock.

‘With insulation, exceeding the minimum requirements stipulated in Part L of the building regulations shouldn’t add much to your budget, since the non-material costs are already factored in. So, it makes sense to incorporate thicker, higher- performance insulation in your design. With the government currently in retreat over feed-in tariffs for renewables such as solar PV, the returns are diminishing. But since your roofers and electricians are already on site, installation costs are much reduced, so it may still be worth doing, reaping longer-term benefits.’

Replacement for a 1930s bungalow

‘We had a new home in six weeks’


Pete and Sue Sadler’s two-bedroom 1930s bungalow in Surrey simply didn’t have space to accommodate visiting friends and family. At first, the couple contemplated extending to get the space they needed, but came to the decision that demolishing and building a replacement was a better course of action.

‘A new house wasn’t actually cheaper,’ explains Pete. ‘But the costs were sufficiently close, and with a renovation and extension the builders couldn’t guarantee that they wouldn’t find problems, making the cost imprecise.’

The amount of time they’d have to spend away from their home while the work was being done also influenced the couple – renovations might have taken 12 months. However, building a conventionally constructed house would have meant nine to 12 months of renting, too, so they opted for a pre-manufactured house from Hanse Haus, constructed with structural insulated panels (SIPs). ‘Typically, this sort of house would take two months for the groundworks and three for the house itself,’ explains Pete. ‘Ours was actually completed in six weeks.’

Demolition of the old house – for which Pete directly employed the contractors – took four days and the foundations and concrete slab for the replacement were then laid. Next, the new house was delivered, built and watertight in under 48 hours, with the rest of the time taken in fitting it out. In place of a bungalow with a separate living room, kitchen and dining room, Pete and Sue gained a five-bedroom house with the open-plan kitchen/living/dining space they preferred.

hanse haus package home bungalow with pale render

The new build has a spacious, contemporary layout and eco features throughout

The new house is energy efficient with triple-glazed windows, and glass wool insulation, which is made from recycled glass together with materials such as sand. The south-facing roof of the property has two solar panels, as well as underfloor heating – an essential requirement for the couple – which means that they don’t have to work around radiators when positioning the furniture. The house also has a mechanical ventilation system to extract moist air and odours from the kitchen and bathrooms, which helps to keep humidity levels down for a healthier interior.

The new build cost around £230,000 in 2010, in a ready-to-move-into condition, including bathrooms, leaving Pete and Sue to fit out the kitchens and utility room, and add fitted wardrobes.