The research also reveals that size of rooms matter, but only up to a point, and that other factors such as age, off-street parking and central heating attract a smaller premium than they have in the past.
Looking at square feet is precise, but isnt the conventional way of categorising property in the UK, estate agents and buyers tend to talk in terms of the number of bedrooms.
Adding an extra bedroom to a property is a good way to increase value, adding more now than it has in the past.
Fionnuala Earley, Nationwides Group Economist, said: Rather than just waiting for the general rise in prices, there are a number of ways to add value to property.
Nationwide research shows that an extra bedroom can add 6 per cent to the price of a property and an extra bathroom more than 5 per cent.
But the research has shown that a loft extension could increase a propertys value by 21 per cent.
Earley said: Building a loft extension to combine the two rather than moving, could make a family £24,000 better off after taking moving costs into account.
But location is still the most important factor. A house in the best neighbourhood can command a price more than a third higher than a similar house in an average area.
The survey revealed that on a like-for-like basis there is up to 90 per cent price premium on properties in the most affluent and prosperous areas compared to those in the most deprived areas.
While a number of factors together add up to the way a particular neighbourhood feels, certain characteristics can be identified.
In an area where the residents are happy with their local authority there is a difference in house prices of three per cent, about £5,500, compared to areas where residents are unhappy.
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