A surprise discovery of asbestos has added nearly $400,000 to the cost of demolishing St. Patrick's High School in Halifax.

Capital Demolition won the contract at a bid of $1.3 million. Demolition is underway, but crews found asbestos in the two wings.

The asbestos was used to insulate pipes in the ceilings and walls, but tests conducted before the demolition began did not detect the material.

"These conditions result in a more intense removal process under Type III containment rather than the simplified glove-bag removal process; these conditions also result in increased manual effort rather than mechanical equipment," says the Halifax council report.

"Discovery of these items required removal of ceilings and removal of walls."

City staff says the demolition contract should be increased by $396,286.80.

Halifax staff originally estimated the entire project would cost $4.5 million, but because Capital Demolition's winning bid came in at $1.3 million, they reduced the overeall budgeted amount to $2.45 million.