The product that is in the building does not continue to sequester carbon. The carbon is sequestered during the growth of the tree, and then it continues to be stored in the products that are used in the building. When forests are harvested in Canada, they're replanted and regenerated, so those new healthy trees are continuing to sequester new carbon out of the atmosphere while the previously harvested products continue to store the carbon from previous periods.
On March 1st, 2018. See this statement in context.