The steep rise ends a period where London has been in the doldrums due to private homes for sale projects falling off as prices for one and two-bed apartments softened.
The surge in the capital helped to drive up total UK sites registered with the NHBC over the three months to August by 11%.
Soaring numbers of both private rental and to a lesser extent housing association schemes lifted house building starts by 145% to 5,774 compared with the same period a year ago.
A business development boss for one major contractor said: “Manchester and Birmingham have been the real hotspots for big build-to-rent schemes.
“While London has had its share of these project things are really taking off now in the capital with many projects out to bid.”
NHBC chief executive Steve Wood said: “We continue to see strong numbers in many parts of the UK with a substantial uplift in London, driven by increased activity by housing associations and the continued flow of inward investment on for-sale and private rental developments.
“The continuing uncertainties around Brexit and the UK’s economic outlook do not seem sufficient to dent confidence in the new homes market, where NHBC’s focus remains on helping developers to build more, high-quality homes for people across the country.”
More than 13,700 new homes were registered to be built in the UK during August, according to the latest NHBC registration figures, with strong growth in London.
Other regions to show growth over the three month trend period included Yorkshire & Humberside and the West Midlands.