The Markit/CIPS construction purchasing managers' index rose to 56 from 53.1, its highest level since December 2015. A figure above 50 indicates expansion.
Builders also hired more workers and ordered more supplies to deal with an increase in new projects.
Economists said the sector was recovering after a slow start to 2017.
The data contrasts with reports earlier this week suggesting greater caution by homebuyers and lenders.
Building society Nationwide said house prices had fallen for a third consecutive in May - the longest run of decline since 2009, just after the financial crisis.
Meanwhile, the Bank of England said loan approvals fell to a seven-month low in April.