4 ms·
> Like, does it really take double digit millions and >2 years to fix some roof panels If it’s made from concrete, absolutely. Virtually every commercial build
by quickthrowman 2y ago
> Like, does it really take double digit millions and >2 years to fix some roof panels
If it’s made from concrete, absolutely. Virtually every commercial building has a flat metal roof with epdm over it because it’s substantially easier to replace it every 20 years. You start on one end, cut out sections, install new roof decking and then install the membrane over it. Repeat until you’ve completed the roof.
For this specific building, everything on top of or attached to the roof needs to be removed and reinstalled. Probably everything inside the building that would be exposed to the elements when the roof is removed would need to be removed and replaced. You need heavy cranes to lift the precast concrete panels into place. If they can’t use the lightweight concrete they used in the 60s, it’s possible the foundations/footings aren’t strong enough to support a new concrete roof which would require structural reinforcements. For trades you’ll have general laborers, heavy equipment operators, steelworkers, mechanical and electrical, concrete.
Double digit millions and two years to replace a concrete roof on a huge building is not outlandish if you understand what construction labor and heavy equipment costs.
Here’s an excerpt from the Wikipedia article about reinforced aerated autoclaved concrete, Ontario has had 30 years to secure funding for this roof and decided not to:
> RAAC has been shown to have limited structural reinforcement bar (rebar) integrity in 40 to 50 year-old RAAC roof panels, which began to be observed in the 1990s
- xattt 2y ago> If they can’t use the lightweight concrete they used in the 60s… Was there something about lightweight concrete from the 1960s that would preclude its use today? Asbestos fibres?
- quickthrowman 2y agoThis building has a reinforced autoclaved aerated concrete roof. > RAAC has been shown to have limited structural reinforcement bar (rebar) integrity in 40 to 50 year-old RAAC roof panels, which began to be observed in the 1990s.[22][23][24][25][26] The material is liable to fail without visible deterioration or warning.[22][26] The material is not the root cause, rather inadequate roof maintenance, which permits water infiltration, and decisions by building owners as to repair or the replacement of existing roofs, which is a part of cost-benefit analysis.[27] > Professional engineering concern was publicly raised in the United Kingdom in 1995 about the structural performance of RAAC following inspections of cracked units in British school roofs,[28] with it being observed that it was likely that RAAC in other countries may exhibit problems similar to those found in the United Kingdom.[18] https://en.m.wikipedia.org/wiki/Autoclaved_aerated_concrete https://en.m.wikipedia.org/wiki/Autoclaved_aerated_concrete More info about RAAC, specifically from the 1950s-1970s https://www.lboro.ac.uk/news-events/news/2023/march/reinforced-autoclaved-aerated--concrete-raac/ https://www.lboro.ac.uk/news-events/news/2023/march/reinforc...
- xattt 2y agoThanks for the detailed! RAAC didn’t parse as a concrete type on first read of your higher comment, but it’s now tied all together. :)