RICS property guides

Guide to extending your home

June 2007

With a little imagination and some expert advice, you could add a conservatory, convert your loft space into the home office or spare room you've always wanted, or even excavate a cellar or basement.

The following guide has been written by RICS (Royal Institution of Chartered Surveyors) and offers advice to homeowners considering developments to their home. Its also useful for those looking to improve their property before putting it on the market, or for homebuyers planning to take on a property with a view to developing it.

How RICS can help you

As the world’s largest professional body for chartered surveyors, RICS offers clear, impartial, expert advice on the issues raised in this guide.

Chartered surveyors cover all aspects of property: from conserving and restoring historic buildings; residential and commercial; industrial and retail to planning home extensions, homebuyers surveys and valuations, dilapidations, boundary disputes, energy efficiency and party walls.

Using the services of RICS members offers real peace of mind because:

• They give you clear, impartial and expert advice

• They are tightly regulated and have strict codes of conduct to protect you – including proper insurance

• RICS members have to update their skills and knowledge throughout their careers, so you can rely on their expertise

• You are further protected by RICS’ complaints service.

Planning a development? Talk to the professionals

An extension to your home is a major project. It will probably cost thousands of pounds and may cause considerable disruption while works are being carried out. Ultimately your extension should, where possible, add value to your property and greatly enhance your living space.

To minimise the possibility of running into problems, consider appointing a chartered surveyor to take you through the process from start to finish and ensure that works are carried out with as few hitches as possible.

Key benefits of employing a chartered surveyor:

• When moving house chartered surveyor estate agents can advise you on which properties have potential for expansion or improvement

• A chartered surveyor can act as your agent when dealing with the planning authorities; they understand planning law and compliance with the Building Regulations and have experience of historic and listed buildings.

• Chartered surveyors have experience in seeking and appointing reliable building contractors and can act as project manager, managing the contract and monitoring the work on your behalf.

• A chartered building surveyor can produce initial designs and then plans for your builder to work to. They can also provide a cost consultancy service – managing your budget throughout the project to ensure you do not overspend.

• If your project runs into problems, chartered surveyors can also offer advice on the best method of settling any dispute that may arise.

Extending your living space

Before embarking on any home improvement project you should first consider:

• the size and shape of your house and garden

• how much additional space you want or need

• how much you can afford

• whether the project will add value to your property.

If you live in a conservation area or your home is listed there may be additional constraints on the type of works – if any – that you can undertake. If you are unable to extend your home beyond its existing boundaries it may still be possible to knock down an internal wall to create more space or even partition a room to add a bathroom or study area.

Planning permission

Planning permission is not normally needed for internal alterations, or for minor extensions or additional buildings within the boundary of your property. However, there may be additional restrictions on permitted development rights especially in conservation areas. The first thing you should do is informally discuss your ideas with your local planning officer to see if permission is likely to be granted. Don't just presume that if the neighbours have a loft conversion or other development that you'll be granted permission too - regulations may have changed over time.

As a general rule, in a terraced house, if your extension is more than 10% of the external volume of your home or 15% in a semi-detached or detached house, planning permission will be required. In Scotland, planning permission is required if the extension is more than 20% of the external volume of your home or 10% for listed buildings or those in conservation areas.

If you are refused planning permission there is a right of appeal but if you go ahead with a building project without permission, you could be served an ‘enforcement notice’ which could mean you are forced to demolish the work you have just had done. If in doubt seek specialist advice from a chartered surveyor – it could save you considerable time and money.

Building regulations

Your extension project may not only need planning permission but also building regulations approval. This is to ensure amongst other things that your home remains structurally safe, protected from fire risks, is energy efficient and has adequate ventilation.

Approval will certainly be needed if you are adding a kitchen or bathroom, adding en-suite facilities to a bedroom or installing electric underfloor or ceiling heating or carrying out structural alterations. Building regulations approval is granted by the building control department of your local authority in Scotland or via an approved inspector in England and Wales.

Once work has started, a building control surveyor will make a number of checks to ensure that the building regulations are complied with. It is important that you obtain a Completion Certificate at the completion of the works. If this is not provided it could prove a problem if you ever wish to sell the property. Fees are payable to the Building Control Body or your local authority for applications for both planning permission and building regulations approval, and these will depend on the value of the project you are undertaking.

All applications are different and the rules are complex so it is well worth considering employing a chartered surveyor to draw up and submit the plans, obtain approvals and oversee the project on your behalf.

Raising the roof

If you need more space but don’t want to lose part of your garden, expanding upwards could be the answer. More than a million homes in the UK now have loft conversions, with the market growing by an estimated 10% each year. Estate agents calculate that an average loft conversion costs around a third of the price of moving to a property with an extra room. And turning your attic into useable space could increase the value of your home by as much as 25%, particularly if you are adding an extra bedroom and a bathroom. However, there are a number of important points to bear in mind:

• Not every loft can be turned into living space and because every house is different, costs will vary greatly so seek professional advice at an early stage

• Bear in mind that you may need planning permission for a loft conversion, particularly if you live in a conservation area, and you must comply with the building regulations

• You may need to seek permission from your neighbours before work goes ahead. In England and Wales party walls regulations apply even if you live in a detached property and do not share a wall with your neighbours. Its best to seek professional advice before building work goes ahead. Visit www.rics.org/partywalls for more information or call the RICS Party Walls helpline on 0870 333 1600 – you will be put in touch with an experienced, local RICS member who will provide you with up to 30 minutes free advice

• Choose your builder carefully (see Choosing a builder on page 10) and consider appointing a professional project manager to oversee the works. Acting as your own project manager can be complex, time consuming and ultimately costly if you have no previous knowledge or understanding of the construction process.

Digging deep

If you don’t have the space or planning permission to extend your house upwards or outwards you could always consider going down. Cellar conversions are becoming increasingly popular for creating fun or practical space - eg home cinema, games room, utility room, storage area. However, they should always be carried out by skilled professionals, particularly if additional excavation is required. The advantage is that you could add an extra storey with little change to the external appearance of your home. However, cellar projects can be complex and may cost up to three times more than a loft conversion.

Check with your local planning officer before starting excavation works. Planning permission is likely to be required if your project includes a light well or if engineering works are needed due to the scale of the excavation.

Choosing a builder

A major extension that involves structural alterations to your home should never be considered a DIY project. When choosing a builder, keep these points in mind:

Do shop around and get at least three detailed quotes. If possible use personal recommendations and check the quality of past projects yourself.

Do ask plenty of questions:

• Does your prospective builder have experience of the work you require?

• How does he expect to be paid – on completion or in stages – and is he happy for you to retain some of the money until the job has been done to your satisfaction?

• Will he agree to independent arbitration should you end up in dispute?

• Will he accept a penalty clause for failure to complete the work on time?

Do use a builder who is a member of a trade association and check credentials with the organisation concerned. You can find professional builders and specialists in your area through the Federation of Master Builders. FMB MasterBond members also meet TrustMark’s government-endorsed standards on workmanship and service. They can offer their clients a ten year insurance-backed warranty.

Do get written specifications and quotes.

Do use a written contract, compile a fully itemised and costed schedule of works and agree a completion date. The Federation of Master Builders provides a plain English contract for use by its members which sets out the agreed work in layman’s terms.

The JCT Building Contract for Home Owners/Occupiers is also suitable for domestic building projects in England and Wales and copies are available from WH Smith. The equivalent contract from homeowners carrying out projects in Scotland is published by Scottish Building Contract Committee (SBCC) and is available from RICS Scotland.

Don’t automatically accept the cheapest quote. Good builders are hard to find and are always busy. It will be worth the wait.

Don’t pay cash in advance on the promise of a ‘cheap’ deal.

Do hold back a sum of 5% that will be released on completion of the works.

Do make sure the builder has a good waste disposal strategy in mind. This will help avoid disputes with neighbours when building work is underway.

Further reading

The Property Makeover Price Guide: organising and budgeting for home improvements

A guide to organising and budgeting for home improvement or development is available from BCIS – The Building Cost Information Service of RICS. It includes:

• Prices for more than 1300 different types of work, including common defects (eg replacing gutters), common alteration works (eg installing double glazing) and total project works (eg adding a conservatory)

• Practical advice on how to plan for building work

• Major property problems – what they will cost to fix

• Alterations and extensions – the issues and typical costs

• Planning permission and building regulations

• Employing a contractor or builder – important considerations and advice

Price £17.99
Published by BCIS October 2006
ISBN 1 904829 46 5

To order; www.bcis.co.uk/propertymakeoverguide

RICS (Royal Institution of Chartered Surveyors) is the largest organisation for professionals in property, land, construction and related environmental issues worldwide. We promote best practice, regulation and consumer protection to business and the public. With 120 000 members, RICS is the leading source of property related knowledge, providing independent, impartial advice to governments and global organisations.