AIC's 44th Annual Meeting

This paper will share lessons learned from recovery efforts in response to a fire at a historic house museum, and in particular from the use of commercial dry ice blasting services to remove charred wood from damaged woodwork. In January 2009, the interior of Craigflower Manor National Historic Site in Victoria, British Columbia was severely damaged by a flash fire caused by an electric heater located beneath its central staircase. Catastrophic charring reduced the thickness of most of the wooden members composing the substructure of the staircase by up to 50% and caused extensive damage to surrounding architectural millwork and interior surfaces.

 In an attempt to salvage the heritage character-defining fir and arbutus staircase, site custodians, The Land Conservancy of British Columbia (TLC) contacted a commercial disaster restoration company shortly after the fire for advice on recovery. The restoration company suggested dry ice blasting. The Canadian Conservation Institute (CCI) was also contacted for advice, resulting in a site visit to inspect the damage, observe the blasting, and provide recommendations for the restoration of damaged architectural woodwork.

 The operator demonstrated the dry ice blasting and the technique proved to be a well-controlled reduction method for the charred wood. At the request of TLC, the restoration company sealed the doors of several adjacent rooms and erected a polyethylene sheeting tent to isolate the staircase and protect the interior during blasting.  Although the restoration company confirmed that dust extraction equipment would be installed in order to capture the primary waste generated by the blasting, after the work was conducted and re-entry was permitted, it was immediately apparent that adequate dust extraction was not installed and the isolation tent had failed. It was also evident that attempts to seal off some adjacent rooms from the dust were insufficient. Not only was the air thick with harmful particulate, but a substantial deposit of the black, carbonaceous dust had settled on all surrounding horizontal surfaces including those of the artifacts displayed in several rooms.

 This paper will elaborate on the circumstances of the initial disaster and the ensuing complications caused by the insufficient capture of primary waste from the dry ice blasting.  It will describe the recommendations provided by CCI for the treatment of the interior millwork and will share results from the restoration project led by TLC.  Finally, it will offer precautionary advice for those who might consider the use of commercial restoration services to remove charred building materials within a historic structure damaged by fire.