How much will it cost to build an Extension

Extension costs

The cost of an extension varies, depending on the size and complexity of the project. General builders will tend to quote around £1,500 per metre² for an extension. Average extensions can cost anywhere between £10,000 and £60,000 for the building works, but interior fittings and decorations will cost extra.

Conservatory costs

Conservatory prices start at around £8,000 for the installation of a simple uPVC double glazed conservatory. ‘The line between conservatories and extensions have blurred, and nowadays our customers are looking for a more integrated living space.

Conservatories can be built up to 8 metres out from the main property (for detached houses, 6 metres for other house types) without needing planning permission. This has led to a rise in larger conservatories being built.

Orangery costs

By their design, luxury orangeries feature more costly components, such as brickwork, pillars and roof lanterns. Our average orangery order is around £35,000.

When you buy from Prestbury Design and Build, you can expect outstanding service. With a price promise, our costing process is made clear and simple – with no hidden fees.

Foundations for you home extension

A home extension or conservatory is only as strong as its foundations and whatever your ground conditions are, we have a solution. Prestbury Design and Build dig up to a metre deep to ensure maximum strength and reinforce the base with steel and insulate it fully.

Foundations at least 450mm wide, up to 1000mm deep we always hit clay.
Packed hardcore 150mm deep
Sand bed
Damp-proof membrane
Floor insulation 70mm to 100mm thick
Steel reinforced concrete slab
Smooth screed floor
300mm cavity wall
Wall insulation 75mm

Do I need Planning Permission for my home extension

When starting any building works to your home, planning permission is may be required. With Prestbury Design and Build, you can rest easy as we undertake all planning applications on your behalf.

Planning Permission and Listed Building Consent

Planning permission is required by U.K. law in order to allow you to build on, or change the use of land or buildings. We will assess your specific extension design and its location against current planning policies and guidelines to establish if planning, listed building or conservation consent is required from your local council. Where approval for the proposed structure is required, full plans will be prepared, submitted and administrated with your local authority by Prestbury Design and Build in order to acquire planning consent for your home extension.

Do you need planning permission for home extensions?

You won’t need planning permission for your home extension if you meet the following parameters.

  • The extension covers no more than half the original garden area
  • It is not situated forward of the main property
  • It is not higher than the highest part of the roof
  • For single storey extensions, it must not extend from the house by more than 4 metres for detached properties and 3 metres for other styles of property
  • A single storey extension is not higher than 4 metres
  • 2 storey extensions do not reach to closer than 7 metres from the rear boundary
  • The brickwork/materials used match the existing property
  • It does not include verandas or balconies
  • Any upper floor, side windows are obscure-glazed

Do you need planning permission for conservatories?

  • Conservatories often don’t require planning permission if they meet the following criteria:
  • They don’t cover more than half the garden area
  • They don’t extend beyond the front or side elevation of the property
  • They don’t feature a veranda or balcony
  • The roof ridge is not higher than the eaves of the property’s roof
  • The house has not already been extended

Building Regulations

Building Regulations are made under powers provided in the Building Act 1984 and set standards in construction for the health and safety of buildings and its users. Complying with Building Regulations is a separate matter to planning permission, the majority of conservatories in England and Wales are exempt from actually needing an application. However, in the circumstances that necessitates an application Prestbury Design and Build will prepare full working drawings (including full structural and heat-loss calculations where necessary) and submit these for approval. We will then notify the local authority at key stages of the installation so the building control officer can make their inspections to ensure the work is completed to their full satisfaction.

Rough Guild

When building an extension, you will need to prove that it is as energy efficient as the rest of the house. If your extension is built on or within 3 metres of a public sewer, then you will need permission from the local water board. Once the work is completed your local building control officer will inspect the extension to ensure that no damage has been done. When building an extension, you must comply with building regulations for:

  • Internal and external walls
  • Plumbing and drainage
  • Lighting and electrics
  • Roofing
  • Foundations and walls below ground level
  • Flooring
  • Ventilation
  • Structural opening
  • Energy efficiency

If your conservatory is built on or within 3 metres of a public sewer, then you will need permission from the local water board. Once the work is completed your local building control officer will inspect the conservatory to ensure that no damage has been done. Most conservatories are exempt from building regulations when they are:

  • Under 30 metres squared in floor size
  • Separated from the original property by an external wall or door
  • Built at ground level
  • Not closer than 1 metre to any boundary
  • Fitted with an independent heating system

Water Board Authority Approval

Where the proposed conservatory or extension is to be installed over or within 3.0m of a public sewer we will seek the permission of the relevant water board authority to gain their consent. Once we have their permission and any recommendations on the construction of the foundations of the proposed base, we will then apply for building regulations as the local building control officer will have to inspect the construction over the sewer.

Party Wall Approval

In some situations a party wall agreement will be required for the proposed conservatory or extension. This is an agreement between two parties regarding the construction on a boundary separating the two properties. In these circumstances we will help obtain this approval.


Our Service

It is essential all approvals are sought prior to work commencing to ensure that the conservatory or home extension meets with all necessary regulation and local authority approvals. If these are not sought the consequences could be disastrous with the structure potentially having to be taken down and the house returned to its original condition. It is therefore really important that Prestbury Design and Build ensure that all these approvals are in place before work commences giving you the peace of mind when purchasing your conservatory or home extension.

Prestbury Design and Build Home Extension Features


When it comes to security, we put security first, our multi-point locking systems, key-locking handles, are standard. All our conservatories also incorporate a unique reinforced wall frame design to provide unrivalled levels of security.

We install toughened glass as standard on all our conservatories too for added peace of mind. And in the unlikely event that your window receives a particularly hard impact, the glass will break into small pieces which are safer than larger shards of glass.

Virtually maintenance free

We understand a home extension or conservatory is one of the biggest investments you can make for your home. That’s why we design and build ours to last, with minimum maintenance and care needed. After all, a conservatory is a place to relax and entertain rather than clean and tidy.

Our home extensions and conservatories are made with materials which need little or no maintenance. Our uPVC frames never rot, rust, flake or peel, and you never have to sand or repaint them. All they need is wash with soap and water every so often to get rid of everyday dirt.

Aluminium also needs virtually no maintenance. It’s extremely tough and hardwearing, and its finishes, which are guaranteed for 25 years, stay bright with only the occasional wipe clean.


Prestbury Design and Build in Macclesfield

If you are looking for a conservatory or extension in Stockport, Cheshire then come direct to the builders and save thousands of pounds. We provide the highest quality construction and then fit your extension with the best cost effective doors and windows from bi-fold doors to sliding doors.

We provide light weight roofs and conventual roof with roof lights to suit your needs.

Then we finish the interior with qualified electrics, plasters and can even decorate and space plan your finished extension.

All oversee by the builders – no sales men involved.

Please contact us for a free estimate and design ideas on Tel: 0161 246 6013