Developers can obtain the same margins from family homes as flats, according to figures from EC Harris and estate agent Knight Frank.

The residential development review for central England, published this week, analyses gross margins from developing a site in the south Birmingham suburb of Selly Oak as townhouses or apartments.

It estimates that building 30 flats in three to four bedroom blocks on each acre would cost £2.55m. Fifteen townhouses of roughly the same height would cost £1.35m. Assuming that the 15 townhouses sold for £180,000 each and the 30 flats for £130,000, an acre would generate £2.7m if developed for family housing and £3.9m as apartments.

Both schemes generate the same gross margin for each acre of £1.35m. “Comparable margins for apartments and townhouses are achievable,” the review concludes.

It adds that other factors, such as offers of discounts to investor buyers, are likely to be “more detrimental” for margins on apartment developments than on family housing.

The report adds that townhouses can be completed piecemeal, providing a quicker return on capital, and planning permission is often easier to secure for family homes.

The review’s publication follows last week’s pre-Budget report in which Alistair Darling, chancellor of the exchequer, provided a fillip to the buy-to-let market with his changes to the capital gains tax regime.