The 39,000sm sandstone-clad Ontario Legislative Building was erected in 1893 in the Richardsonian Romanesque style to the initial designs of Architect Richard A. Waite. The north wing Library was completed in 1910 to the design of George W. Gouinlock. Being constructed with a facing of Sackville red sandstone the exterior of the building has proven to be not as durable as the main building constructed of Credit Valley sandstone.

ArconTEST was retained by the LAO in 2019 to assess the condition of the North Wing masonry.

The grey-to-brown red Sackville sandstone is visually appealing but found to be susceptible to contour scaling and freeze-thaw weathering caused by the high feldspar content in the stone. Later interventions (2009 and 2010) using St Bees sandstone were found to be in better condition.

A set of base drawings illustrating the walls and parapets were prepared. The condition of the parapets, main walls and previous repairs were evaluated and transferred to as-found condition drawings for later use.