All of the plaster and concrete in danger of falling has been removed. This has revealed extensive deterioration in the concrete slab the serves as the roof/ceiling structure. Over 50% of the bottom surface of this slab (on which the ceiling plaster is applied) has deteriorated. When the plaster was removed the concrete crumbled away in many places. There is also extensive exposure of the reinforcing bars (metal bars that are poured into the concrete for structural stability). These bars are very corroded and in some locations have rusted completely away.
This has been a long developing situation and is not the cause of one single factor or event. Our structural engineer believes that there is evidence that this deterioration has been occurring for at least 50 years. Some of the causes include:
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Water exposure from leaking roof drain system
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Water exposure from cracks surface concrete in upper concrete walls of Unity Temple (commonly referred to as parapet wall)
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Original design and construction flaws (poured in place concrete technology was very new in 1905-08)
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Inadequate or faulty repairs in the past
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The age of the building
The next step is to conduct an assessment of the roof/ceiling slab from the top. This will require contractors to open up the existing roof system (insulation and roofing membrane) so that the structural engineer can see the condition of the concrete slab from the top. They will also chip out some concrete in locations so that we can examine the reinforcing bar and several cores of the entire slab section (a small cylindrical section is drilled through from top to bottom) will be taken for analysis. This will occur as soon as we have several dry days of weather in a row.
Once the assessment is complete, our structural engineer can create his report and develop the correct repair solution. Given the extensive deterioration, it is likely this will require taking out complete sections of the concrete slab and re-pouring the slab with new concrete and reinforcing steel. Originally we had hoped that we only need to patch the concrete in localized areas. Unfortunately it now appears this project will require more extensive concrete repairs. #
