If one thing epitomised the boom years in the housing market it was the building of high-density blocks of apartments that were sucked up off plan by eager investors.

The credit crunch has changed all that. Outside of London dense schemes of flats are rapidly going out of fashion.

Having been for many years gradually squeezed out of house builders' product mix by flats, houses are making a comeback (well proportionately anyway). And there are many people predicting that the days of half the new housing stock coming as apartments are dead.

Research I have been doing for the annual Housing Market Intelligence report shows the first signs that developers are turning back to what they know and trust most - building houses.

Using planning data from the Barbour ABI database, the research shows that as far back as late 2005 there were the first turnings away from a trend that had made the two-bed flats the standard unit of production for house builders.

Part of the research compared the number of new homes approved within schemes comprising only houses with the number of homes given planning approval in flat-only schemes. This was to gain a sense of how the balance has shifted.

At the start of the decade the number of houses outweighed the number of flats by almost two and a half to one. By the third quarter of 2005 the balance had turned to 1.6 flats for every one home given permission. But since then, we have returned to a ratio of one to one.

Further research looked at new or repeat applications for house-only and flat-only schemes. And the results suggest that house builders are now much more likely to go for new schemes of houses rather than of flats.

What also comes out of the research is that there is a move away from the ever increasing height of residential schemes.

The move away from flats is in many ways pretty predictable, given the impact of the credit crunch. What made flats attractive in the boom was that they could be pre-sold relatively easily and there were plenty of investors keen to buy and sell on or buy to let.

But in less buoyant markets flats represent greater risk, as you can't build them out gradually to meet demand. You have to finish the block and sell it.

In tough financial markets they can represent a huge risk unless you have a big investor eager to take the lot off your hands.

Also flats have become associated with all that is wrong in the housing market and there is a perceived over supply. This does not play well with potential buyers. So little wonder that house builders are reining back on building them.

This does not mean an end to flats. In London and within mixed schemes flats will remain a major element. But we appear to be seeing a sharp change in the product mix in favour of houses and of lower rise.

The net effect of this turning tide is likely to be a reduction in the density of housing schemes. This in turn means that more land will be needed, when the upturn comes, for building the homes the Government says it needs.

This is a point strongly and independently made in the Housing Market Intelligence report by both John Stewart, Economics Director of the Home Builders Federation, and Richard Donnell, head of research at Hometrack.

The big question this leaves is how will the planning authorities and more importantly the Government deal with this thorny issue when it arises, as it looks almost certain to do?