Poor workmanship, delays and unexpected costs can all turn a buyer’s dream new house into a nightmare.

“A new-build home can appear less problematic than buying an older property,” said a spokesperson for Which?, a consumer interest magazine. “However, you could experience delays in the completion or be hit with unexpected costs.”

Here we take a look at what you need to know before you decide to buy new.

Plenty of people buy new-build because of the perceived lack of hassle with maintenance and the fact that you in effect have a blank canvas on which to make your mark.

“They are all nice and shiny and feel fresh and new,” said James Greenwood of Stacks Property Search. “Often you can get engaged with the developer in the final stages and fine tune the property to what you want it to be and that can be cost-effective.”

New homes also tend to be more energy efficient though you might be surprised that many are not more so.

The majority of new-build homes also come with a guarantee from the builder. The downside of these guarantees is that they come with plenty of small print and making a claim under them is not always easy or quick.

The biggest downsides are often cited as depreciation and space. “A new property is only ‘new’ for a very brief period, and you will be paying a premium of as much as 25% for its newness, much as you do when you drive a new car out of a showroom,” says Greenwood.

“So it’s always worth comparing similar ‘old’ properties, in terms of value, space, rental value and so on. Check the price per square foot and compare it with the resale market so you understand the extent of any premium you’re paying.”

Space is an issue because new homes are often deceptively small.

Plenty of buyers make a commitment to buy before the property is finished, and often rely on the developer’s show home to get an idea of what they’re signing up for. However, developers will use crafty tricks to make you think there is more space than there is. Furniture will often be minimal and scaled down to give an illusion of more space.

For example, a double bed will be 4ft rather than the more standard 4ft 6in. Flattering lighting, wall mirrors and glass-topped furniture can all add to the feeling that you’re buying a much bigger home than you are.

“One of the shocking things about new-build in my view is the size of the plot,” says Greenwood. “Often there is not enough room to get a trampoline in the garden, let alone build an extension.”

A shiny new property can also hide a multitude of sins. In a Which? survey that identified the extent of new-build niggles, a quarter of problems related to boiler issues, while 16% of people experienced difficulties with their utilities, and 12% were faced with structural problems.

And don’t presume that a survey is unnecessary. Greenwood thinks this assumption would be a mistake.

“We have pulled out of a number of new-build purchases for clients on the basis of asurvey because things were unsound,” he says. “I would recommend a full structural survey.”

Buyers should also keep a close eye on the anticipated completion date. A mortgage offer is typically only valid for six months and the timetable to complete can drift.

This means that if you arrange your finance early, you could lose your mortgage offer if the completion date dragson.

Guardian News and Media 2013