Barratt has snapped up land on seven sites to build 1,400 homes so far this year.
It has also started work on 11 new sites or new phases on existing sites, which together will deliver a total of 1,724 units.
These include developments at Altitude in Aldgate, Osiers in Wandsworth, Maple Quays in Canada Water and St Andrew’s in Bromley-by-Bow.
The strength of the London and south east market is helping to drive the volume house builder’s recovery.
In a trading statement, Mark Clare, Barratt chief executive said: “We have had our strongest spring selling season for five years.
“Our overall pricing levels have been maintained and average weekly net private reservations in the period are up 25% compared to last year.
“As a result we’re ahead on achieving our objectives of improving profitability and reducing net debt.”
The average number of building sites is up to 397 compared with 374 in the same first half period last year.
Clare said: “Whilst the economic outlook remains uncertain and the availability of mortgage finance continues to be a constraint, we expect the benefits of the various Government initiatives to continue to provide support to the industry.”
Barratt estimates the total number of completions this year will reach 12,600, up from around 11,000 the year before.