Demolition of the former magistrates court was suspended last month to allow seagull chicks to fledge their nests on the roof.
A Vale of Glamorgan council ecologist has now ruled that the young birds, while still visible on the building, are now capable of avoiding contractors.
Fifty two houses, flats and shops are being built on the site where Aberdare Demolition is now back at work after originally starting the job in May.
Gulls are a protected species and it is illegal to harm the birds, their nests, chicks or eggs.
Newydd Housing Association chief executive Paul Roberts told the BBC: “We would like to to thank Aberdare Demolition for securing the site and monitoring the birds over the last few weeks whilst demolition was at a standstill.
“They have been very helpful during this waiting game.
“We would also like to thank local residents for also monitoring the site for us and informing us of any seagull sightings.
“We look forward to the construction of these new affordable homes and will continue to inform residents of progress on the site.”