The speed skating oval in Richmond, B.C., that is still under construction for the 2010 Winter Olympics already needs some of its roof membrane replaced.

The $178-million project — already triple the cost first projected — needs to have the portion of the roof membrane replaced that covers the wood panels making up the main roof, city officials said.

Over the past two months, tests have determined that some fungi and algae have developed on the bottom of one of the two insulation layers covering the roof, said Greg Scott, director of major projects for the City of Richmond.

The main roof structure was completed in January and consisted of hundreds of panels of B.C. wood that were lifted into place and secured like a checkerboard. Two layers of insulation were placed over the wood roof and a protective membrane placed over the two insulation layers.

Scott said fungi and algae were discovered at the bottom of the first layer of insulation, next to the wood roof.

"We've got to take the membrane off to get at the lower piece of insulation," he said.

About 70 per cent of the roof area insulation needs to be replaced, he said, and the top protective membrane must be removed as well as the top layer of insulation to get at the bottom insulation layer.

"Then we do an inspection to see if there is fungi or algae growing on it and if there is, throw it away and put a new piece of insulation down and continue."

Replacement costs are covered by Richmond, the oval's owner, and are estimated at between $2 million to $2.2 million, Scott said.

The city is looking at recovering the replacement costs from the contractor that installed the insulation, including taking legal action if necessary.

City spokesman Ted Townsend said the wood roof was not affected by the fungi damage.

The oval, the largest building constructed for the 2010 Winter Olympics, is scheduled to open this autumn.