spaces in between. The plasterer would apply slight pressure to push wet plaster material through the gaps forming plaster “keys” that ultimately hold the plaster in place.

When HPCS conducted investigation of the plaster ceiling condition in 2012. The lug and key pull test was used to determine plaster adherence to lath. Results showed the plaster ceiling strength to be inadequate as there was inadequate keying with a high proportion of the plaster with weak connection to the wood laths. Although there was no sign of imminent failure, the ceiling was “inherently unstable” due to the original poor application of plastering, but has survived due to the gothic arches it is applied on (more vertical than horizontal). Consolidation of the plaster was deemed to be necessary, particularly to mitigate any future damage from needed construction activity/structural interventions above the ceiling, and was recommended to be completed prior to such activities.

Since roof stabilization became one of the first priorities to be addressed in the Assumption Church Restoration project as part of the Phase I work, HPCS was engaged again in 2019 to reassess if the plaster repairs could be delayed until after some components of other building restoration items (such as roofing replacement) had been conducted. HPCS provided a follow-up surface inspection and the report (dated April 15, 2019) confirming that there is no indication the plaster posed an imminent danger of collapse, however, that most of the ceiling was experiencing much more movement between lath and plaster than how it should perform if in good condition. Also, at locations of water damage, the condition of the plaster posed a safety risk and would not be able to undertake additional stresses without further intervention. The cast plaster stars which were a later addition to the ceiling were also recommended to be better connected to the ceiling as part of the plaster consolidation.

Although the study concluded there was no sign of accelerated deterioration since 2012, the condition of the plaster was assessed as not able to undertake additional stresses of major building interventions particularly above the ceiling. HPCS first recommendation was to handle the plaster consolidation first. However, a second mitigation option to have other work done first was proposed to be acceptable conditional on the following:

• If the scope of building interventions were reviewed by the HPCS along with other building expertise to assess the impact on the plaster.

• Marked areas noted with a high degree of deterioration to be covered with solid sheets prior to reoccupation and the floor areas below cordoned off from public access.

• There would be minimal risk to the public if some building upgrades were made and reoccupancy of the building happened, with the plaster work conducted around a year after.

Prior to re-occupancy of the church building, HPCS confirmed the implementation of their recommendations for mitigation. These measures were stated to only serve short-term mitigation for a year (by August 2020) during which full consolidation of the plaster