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Excavations on The Grange portico

September 7th, 2010

Excavations on the Grange portico

Excavations on the portico continue. As we dug further under the slab we ran into some problems. There is an air duct on both sides that run under the porch and then into the building. When this was installed, some of the porch foundation was removed weakening the structure. On the west side, the portico slab is actually no longer supported resulting in the slab physically sitting on the step. At this point we are waiting for an engineering review to determine how to brace the whole portico and raise it up very slightly so that the step can be removed and we can work on the foundations.

The south east chimney is now finished. It was taken down to the roof level. Work on the south west chimney is almost complete. The final step will be installing the caps and new flashing. We had an unexpected problem during the very hot days this week. The mortar was drying too quickly and not able to cure properly. In a few places cracks were forming. The masons had to soak the bricks prior to laying them, spray the new masonry with water every hour and cover completed work with damp burlap for at least 72 hours after installation. The cracked areas had to be repointed.

Excavations on the Grange portico

A Heritage Construction Moment

How do we make decisions? In the case of the portico, it would be easier and cheaper to remove the old foundation and pour a new concrete one—so why don’t we? After all, no one will see it. We are guided by several documents. The Standards and Guidelines for the Conservation of Historic Places in Canada provides a common set of standards that are to be used throughout Canada in the preservation, rehabilitation and restoration of heritage buildings. There are 9 standards that apply to all projects. These identify the need to retain all the character defining elements of a building. Because The Grange is a national historic site, the AGO agreed to follow Parks Canada’s “Cultural Resource Management Policy”. This policy lays out principles and practices for managing a cultural resource. Again, the focus is on preserving the character defining and heritage attributes of the building. There are a number of international charters that deal with preservation, but the most commonly used one is the Burra Charter. Developed in Australia, this Charter provides guidelines on determining cultural significance, conservation policy, procedures and ethics. Reviewing these three documents can help us make and justify decisions. As enough of the original fabric and construction technique remain of the portico foundation, these documents support the restoration the foundation rather than replacement of it.

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