Developers transforming the residential skyline of Birmingham were today given a stark warning - create the 'right mix' of homes or face an increasingly bleak future.

The message is hammered out in a new research report on the city's commercial and residential markets from property consultancy Knight Frank.

In its annual Birmingham Market Activity report, Knight Frank says the need for a 'cohesive' Birmingham - where the mix of uses is tailored to the require-ments of a city with a growing global importance - is vital.

New apartment developments which possess no unique selling features will face an increasingly tough market - and with an estimated 8,000 apartments built in the city centre and up to 10,000 more with or awaiting planning consent, Knight Frank says this won't be welcome news for many developers.

In marked contrast, the commercial aspect of the report indicates a strengthening office market for Birmingham.

Take up in the city centre has increased by 12 per cent, prime rents have increased by 20 per cent and overall there has been a revival in commercial development activity with continued appetite for sites and accommodation within the city centre from UK and overseas institutions, private buyers and syndicates.

According to Knight Frank, the improved perception of the city - combined with anticipated prime rental growth from £32.50 per sq ft to £35 per sq ft for new Grade A space - is also having positive knock-on effects in the secondary office market.

David Fenton, head of residential development for Knight Frank's central region, said: "Our research shows that the emphasis will increasingly be on creating communities and focusing on creating the right mix of homes and uses which will appeal to a wider market.

"Standalone apartment schemes where the prominent purchasers are buy to let investors simply cannot supply all of the city's needs.

"Indeed, we would go as far as to say that we have come to a stage where only apartment schemes with a true unique selling point - such as iconic architecture or developed as part of a mixed use scheme - can expect to reach target values in the current market.

"A broader mix of housing must now top the city's development agenda with sustainability the buzz word of the moment. For the city's housing market to survive it is vital that developers seriously consider where the demand is coming from and for them to design the correct mix and style of homes to adhere to this.

"Developers need to consider the nature of the product they are building and whether there is the market to support it within the city core.

"Even in light of fears of a downturn in the market, as long as developers can achieve the right mix of property and start introducing the right product to the city, there is no reason why Birmingham city and its suburbs cannot continue to grow with the success it has been associated with in recent years.

"Going forwards it is the schemes in city fringe locations such as Icknield Port Loop by Edgbaston reservoir and inner urban areas such as Park Central on Bath Row that present a real opportunity to pioneer sustainable mixed use developments with the delivery of large scale family housing, at the same time as promoting long term sustainability."

Mark Swallow, head of Knight Frank's Birmingham office, also said: "Birmingham is now in a position where it can respond to larger enquiries and have a serious offering for further Government relocations, major blue chip companies and headquarters.

"More than 1.1 million sq ft of accommodation is under construction in six separate schemes and this will in turn lead to job creation and population growth. In this position we are well placed to attract more high profile inward investment opportunities and drive growth across all sectors."

Clive Dutton, director of planning and regeneration at Birmingham City Council, said: "Our commercial offer has improved greatly with Baskerville House and Colmore Plaza and this will continue with Eleven Brindleyplace, Snowhill and Arena Central.

"It is vital that our residential offer follows suit - evolving to provide innovative sustainable product, we intend to drive this forward at Birmingham City Council over the coming months."