Ever wanted to build your own house from scratch or completely redesign the one you've already got? Maybe you just want to make your home greener or build a kitchen extension? How can you get professional advice without hiring an expensive architect or designer?

A good starting point is the Des Res exhibition public weekend, starting tomorrow in London. There you will be able to consult one of the capital's leading architects in a 20-minute one-on-one session, for free. Here, the experts give us a sneak preview of their advice on everything from maximising your home's value to building your very own grand design.

Our panel consists of: Marcus Lee, FLACQ Architects (flacq.com ), Ivan Harbour, Rogers Stirk Harbour (rsh-p.com ), Dominic Cullinan, SCABAL (scabal.net ), Sarah Featherstone, Featherstone Associates (featherstone-associates.co.uk), Catherine Burd and Buddy Haward, Burd Haward Architects (burdhaward.com), Luke Tozer, Pitman Tozer Architects (pitmantozer.com ), and Alex Ely, of Mae Architects and the author of The Home Buyer's Guide (mae-llp.co.uk).

BUILDING YOUR OWN HOME

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Don't underestimate the financial and emotional commitment - it's invariably stressful but usually worth it in the end.

Design with change in mind. Consider how important flexibility is in the design process and afterwards.

Go for as much volume as you dare and fit out later if needs be. Extensions can be expensive.

Don't worry about “value”. Estate agents only go on what they sold last week. The value is yours to judge and quality of life is paramount.

Accept that it will never be finished.

Do it when you're young.

Get the location right - you can change most things about a building, but not that.

Appoint a professional team to help you: find an architect whose work and manner you like - it's a really important relationship and you need to trust and respect each other. Get recommendations and take your time. The Royal Institute of British Architects website (architecture.com) offers an excellent client advisory service.

Be a good client - be clear about what you really want, prioritise and be realistic about how much you can spend, then take their advice.

When work starts on site, go on a long holiday and do not come back until it's finished.

“GREENING” YOUR HOME

Solar panels are the ultimate way to achieve a large reduction in carbon emissions as water is heated for up to six months of the year via passive solar gain. But at a cost of about £3,000, it may not suit all budgets.

Heat rises, so the most important place for good insulation in a home is in the roof, followed by the walls.

Other small-scale measures are: water reduction, double glazing and installing a condensing boiler.

Use recycled and reclaimed materials, such as Thermafleece sheep wool insulation from Second Nature, which costs £10 per square metre.

Other approximate costings are: low-flush lavatory, £50

Organic paints used internally throughout: £1,000

Low-energy light fittings throughout: £100

Draught-proofing to all external windows and doors: £750

Water butt: £150

Compost bin:£50

Reclaimed timber floorboards: £500

EXTENDING YOUR HOME

Extension costs vary hugely, but expect to pay approximately £5,000 for a very basic professionally fitted conservatory, £35,000 or more for a loft conversion, and at least £50,000 for a roof extension.

Whether you are adding, converting or extending, your works will need to meet the requirement of the local authority building inspector, and you must pay a fee, as laid down in the Building (Prescribed Fees) Regulations 1994.

Your builder must comply with building regulations. They ensure public safety and cover fire protection, means of escape, drainage, structural requirements and disabled access.

If you want to build an extension that will sit on your neighbour's boundary, you may need to take down their fence or dig up part of their patio. Hire a party wall surveyor to help negotiations, agree any compensation and remedial works due to both parties.

The cost of hiring a surveyor is dependent on the scale of the project, but expect to pay up to £950+VAT per wall in question.

Consult the Royal Institution of Chartered Surveyors (rics.com) for impartial, expert advice on the issues.

Consider hiring an architect; as well as offering design services, they can manage the planning application on your behalf, advise on building regulations and deal with builders. RIBA can give you local contact details.

MAXIMISING THE VALUE OF YOUR HOME

Kitchens and bathrooms sell houses. On average, their fittings are replaced at least five times during the life of a home. Remember to budget for labour, stripping, demolition and damp-proofing as well as materials and appliances.

Kitchen

The better planned it is, the better long-term value you will get out of it. For example, if your kitchen is open-plan, then the noise of a washing machine in mid-cycle will not add to your quality of life. Isolate the washing machine in a cupboard. Think about the three principal functions: food storage, preparation and cooking. There should be a variety of storage on offer: cupboards, drawers, open shelves and racks. A working triangle between the three main activity zones - the cooker, sink and fridge - is the most ergonomic.

Cost including appliances: £15,000-£20,000

Bathroom

Consider how you will use the space. Would a view of the sky improve the quality of your bathing? Would lighting and shelving help if you wanted to read in the bath? Would a separate lavatory help to avoid bathroom bottlenecks at busy times of the day? A well-designed bathroom will have space around the bath, a medicine cabinet out of reach of children, a sink with adequate elbow room and plenty of ventilation.

Cost including white goods: £7,000-£12,000

Garden

Creating a garden from scratch - whether it is building a patio or erecting a trellis - can be expensive. Start by finding out what type of soil you have; this will affect the type of plants that will grow. Large plants near the building will affect the quality of light entering your home, but trees can provide shade in summer, and let in light in winter once the leaves have fallen.

Cost: £2,000-£3,000

Fact file

The Des Res public weekend runs tomorrow and Sunday at New London Architecture, 26 Store Street, London WC1E 7HP. Opening times: Saturday 10am-5pm, Sunday 11am-5pm. Talks are free, but booking is essential: 020-7636 4044, newlondonarchitecture.org/desres

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