Bring your garden indoors all year round

Spring is here and our fancy turns to conservatories; they can add value and give much pleasure – but beware the pitfalls.

Along with daffodils and crocuses, the first hint of spring is the stirring in the minds of householders that something has to change. But with the housing market still in the doldrums, those who in the past may have started browsing the property websites are turning their thoughts instead to improving their existing homes.

The warmer, longer days often lead to thoughts of a conservatory, that room in the garden that, so the manufacturers and lifestyle gurus tell us, brings the outdoors indoors all year round. But are such rooms always a good idea?

"On the whole, conservatories are a good thing," says Philip Macdonald, the managing director of Abbotts estate agents. "But the quality is very important. It has to be more than a lean-to or a greenhouse in disguise. But get the quality right and not only do you give your family the flexibility of an extra reception room, but you can substantially add to your home's value."

Mr Macdonald, whose Suffolk and Norfolk estate agency forms part of the Countrywide group, reckons that the extra usable space can add up to 10 per cent to the asking price, so on a £300,000 home anything less than £30,000 spent on a conservatory will be more than matched by the increase in value. It will also add to the kerb value. "Conservatories appeal to families who could use the extra space as a playroom, to gardeners who can nurse seedlings and leave their muddy boots inside, without having to traipse through the sitting room, and anyone who just likes to sit in comfort and enjoy their garden all year round," he says.

But this will only be achieved if the conservatory is a fully habitable room 12 months a year, with a proper heating and ventilation system, and no hint of damp or mustiness. It must also be the right size: too small and it loses its right to call itself an added reception; too big and it can dwarf the garden.

Size and design are the next considerations once you have decided that a conservatory is the way to go. Professional help at this stage could prove invaluable later on, says Jane Duncan, the vice-president of the Royal Institute of British Architects (Riba).

"If you are sure that a conservatory is really what you want, know where it will be built, your house is not listed or in a conservation area and you don't want a bespoke design, then one of the big manufacturers and installers will be able to provide all the information you will need for an off-the-peg room," she says.

"But, an architect will ask awkward questions. It may turn out that you don't actually need a conservatory at all, but it would be better and cheaper to redesign the living space that you already have. If it's more light you're after, maybe opening up the back of the house with French windows would be a better option."

From 18 April through to July, you can book a consultation with a local Riba-registered architect, to clarify your needs, for a £40 donation to the charity Shelter. To register your interest in taking part in the scheme visit architectinthehouse.org.uk.

A local architect will also be fully aware of the quirks of your local planning officers, and, of course, will know how to avoid problems with planning permission and building regulation restrictions with small tweaks to the design. "There is a common misconception that conservatories do not need planning permission; that they will always come under 'permitted development'," says Ms Duncan, who runs her own practice in Amersham, Buckinghamshire. "But they are, in the end, a glazed home extension, and although they can be built without permission, you need to be careful you don't fall foul of the restrictions. There is nothing worse than the council taking enforcement action against your conservatory. That is an awful experience."

It can also be a costly process, and homeowners, she says, might find that seeking advice at the beginning of your project can save you more than you spend on an architect's fees. The cost of a conservatory can vary hugely from around £500 per square metre up to thousands, depending on the design and the materials you chose.

There are three main frame materials: uPVC, aluminium and hardwood, which all have benefits and drawbacks. uPVC offers good insulation, little or no external maintenance, and is the cheapest, but check the thickness of the system. Thinner materials, around 50mm, will cost less but will be flimsier. Most installers will offer between 60 to 65mm, some up to 70mm.

Aluminium is stronger and is often used for large, public conservatories. It is costlier than uPVC and does not have plastic's insulating properties, meaning your conservatory could be freezing in the winter and boiling in the summer, requiring a possibly expensive sophisticated heating and ventilation system.

The high-end of conservatory design is hardwood, which wins in the aesthetic stakes, but requires more maintenance to keep it in good shape, and is the most expensive of the three. As with uPVC, check the thickness of the timber to be used, as an immediate cost saving may not be a wise move in the longer term.

So you have decided you want a conservatory, you know what you want it to look like, and have worked out what you will need to spend, not forgetting the costs of furnishing and heating, or cooling, your new garden room. Now you need to consider how you will pay for it.

According to Tim Moss, the head of loans at moneysupermarket.com, there are five options.

"If you are looking to achieve a quick sale on your house, and adding a conservatory will help you achieve the price you need, then you could consider taking advantage of your installer's deal. Most of the large companies offer a 0 per cent loan, but only over six months. So you need to sell your house and recoup the costs in that period before the high interest rates kick in. It may be a big risk in this housing market."

Option two is to use a credit card, many of which feature 0 per cent on purchases, including Marks & Spencer, which is offering a 15-month deal. "This could be good value, but you have to be careful – you don't want it to spill over the interest-free period. That could prove costly," says Mr Moss.

Option three is to use your savings. "If you're lucky enough to have savings, your money is probably only earning around 3 per cent," so it makes sense to spend that rather than arrange a loan at around 6.8 per cent.

Option four is to take out an unsecured loan, as lenders look on borrowing for home improvements, rather than for debt consolidation, favourably. Mr Moss suggests the 6.8 per cent deal from Sainsbury's for a loan of up to three years is a good deal.

The fifth, and for Mr Moss the least attractive option, is to remortgage your house. "Normally, I would never recommend extending a mortgage, particularly to buy something that will depreciate over the years, but for home improvements there is a case to be made," he says.

"If taking an extra £10,000 will add £15,000 to the value of your house then you are using an asset to improve that asset."

Planning Ahead: What you need to know before you build

A conservatory is generally considered to be permitted development, so does not need planning permission, within certain limits – mainly to do with the volume of floor space, and its height. If your home is listed, or in a conservation area, or in an area of national beauty, then the restrictions are greater.

A conservatory is also generally exempt from building regulations as long as it is less than 30 sq m; separated from the house by external quality walls, doors or windows; has an independent heating system; and the glazing and any fixed electrical installations comply with the applicable building regulations.

Any new structural opening between the conservatory and the existing house will require building regulations approval, even if the conservatory itself is an exempt structure.