EU debate: do we need a house every seven minutes to cope with immigration?

"We need to build a house every 7 minutes just to cope with immigration into this country."

Nigel Farage, BBC EU debate, 3 April 2014

This is actually an old claim: in 2010 the Sun newspaper ran the claim prominently, based on a study by Migration Watch. It applies to England alone rather than the whole UK.

At the time it was based on the government's estimate that the number of households in England would grow by about 232,000 per year up until 2033, in line with rising fertility, life expectancy, and net migration.

Without any net migration, it was projected that there would only be 149,000 additional households per year. So the difference - 83,000 households a year (over 200 a day or about one every six to seven minutes) - is what these figures suggest is the effect solely due to migration.

So the figure does have a basis, though we have two reasons to be cautious.

Estimates have changed

The figures are based on old household projections, and they've since been updated. The new figures don't measure the effect of migration, but they have revised down their overall estimates. It's now expected there will be 221,000 new households per year for a decade.

We do know from latest projections that the population is expected to grow by 418,000 per year, 157,000 of which is attributed to net migration. In other words, migration accounts for about 38% of population growth.

This is unlikely, on its own, to drastically change the net migration estimates. But it does show that, in the space of a few years, the projections can change. Predictions for decades into the future can't take into account the effects of government immigration policies, for instance. Overall, the estimates are uncertain.

We don't know what a migrant household looks like

Just under 110,000 houses are actually built per year in England, which suggests that overall supply isn't meeting demand.

But this is quite a crude comparison since households can have different sizes. The average household in England has 2.4 people (and is expected to fall to 2.3 in a decade) and the average number of bedrooms in new houses and flats built is at least 2.7.

But households made up of recent immigrants won't necessarily be typical either, and the Office for National Statistics told us there aren't published estimates for these households alone.

So at best comparing household projections to migrants' demand for houses is a broad-brush indicator, and there still seems to be an evidence gap in calculating the number of new homes that will be needed due to migration.