Facade-ectomies

[AdamBC]

Question for those of you who are in the industry - currently when we have a building from the brick and granite era, we'd prefer to see the builder save the facade, however does a facade-ectomy change the facade in a way that can't be salvaged?

For example, looking at Russia Wharf, or Filenes, assuming that the politics and valuations change and all of a sudden, a 60 story tower is appropriate for those spots, can the old facades be reused once the 30 story towers are taken down? How would the towers have to be taken down to retain the old facades and what state would they be in?

Would love to hear some technical details of what to expect if it were to happen.

 

[Lurker]

The major cost is not preservation of the facade, it is the engineering of the new foundations.

Typical load masonry facades facades are perfectly self supporting, remember they are designed to carry floor loads, but they still require temporary bracing to avoid toppling under a wind load. Temporary bracing and tying the existing facades to a new structural skeleton isn't too difficult other than some expansion and building envelope details.

Foundations on the other hand are extremely expensive and require complex engineering. Undermining the existing foundation and footings, such that the original facade doesn't collapse and subsidence of surrounding areas does not occur, is quite difficult. Often special excavation and a new foundation will need to be constructed underneath the facade to be preserved prior to the construction of the new project. This was what occurred at Russia Wharf and Filenes.

The alternative to this is to set a new foundation at a safe district from the existing in a manner which does not compromise the the soil pressure and then bridge the distance in between with pilings and some long span structural steel or trusses. This is usually not ideal in terms of having anything resembling an efficient footprint in the redevelopment and prevents any subterranean program. However, sometimes in the case of the need to preserve a part of a structure otherwise impossible to save, like a precarious foundation built on sand, while relatively isolating the new structure from the existing, than this can be the most desirable of the least desirable options.