Ontario Science Centre doesn’t require full closure: A close reading of the engineers’ report

A deep dive into the engineers' report suggests that the building’s key exhibition areas could continue to operate safely—even if the Ontario government chooses not to invest in any structural roof repairs by the fall.

Construction fences were erected on Friday, June 21 around the perimeter of the Ontario Science Centre, following a provincial announcement of the Centre’s immediate and indefinite closure. Photo by Elsa Lam

This article is part of a series including a previous article debunking the business case for the Ontario Science Centre’s relocation and a later article demonstrating how an expensive temporary location of the Science Centre would not be open for two years.

On Friday June 21 at 4 pm, the Ontario government announced that the Ontario Science Centre’s landmark 1969 building, by Japanese-Canadian architect Raymond Moriyama, would be closed immediately, for an indefinite period of time. It cited an engineering report by Rimkus to justify the closure, saying that the report found “serious structural issues with the Ontario Science Centre building.” While these issues would not be expected to materialize until the winter, according to Infrastructure Ontario, the intervening months were needed “for staff to safely vacate the building.”

But a deep dive into the report reveals a different story. It suggests that the building’s key exhibition areas could continue to operate safely for years to come—even if the Ontario government chooses not to invest in any structural roof repairs this year.

The issue at stake is the presence of Reinforced Autoclaved Aerated Concrete (RAAC) roof panels, sold under the brand name Siporex, which make up 57% of the Science Centre’s roofs. A popular material in Ontario from the mid-1950s to mid-1970s, the lightweight panels were made form an aerated blend of sand, Portland cement, and aluminum.

A palette of Reinforced Autoclaved Aerated Concrete (RAAC) blocks. Photo by Leo Miregalitheo via Wikipedia Commons

However, concerns have been raised that the panels have an overall reduced robustness compared to steel decks or traditional concrete, especially if there are leaks in the area. It’s a known issue—over the past decades, the roofs of the Ontario Science Centre have been monitored and sections of the RAAC roof panels have been replaced with steel decking.

Rimkus’s report is a comprehensive, panel-by-panel visual assessment of all accessible RAAC roof panels in the facility. It recommends a staged approach to addressing the RAAC issue once and for all: by removing and replacing all remaining RAAC panels with steel deck roofs, mostly when they come up for regular scheduled renewal over the next 10 years.

In assessing the panels, Rimkus found that a total of six of the 18-inch-wide, 5 or 10-foot-long RAAC panels in the facility were in what it deemed “critical” condition. These was reported as soon as they were identified, and all of these panels have been shored or are in the process of being reinforced.

Rimkus assessed a number of additional RAAC panels as being in “high risk” condition, and recommended that these be reinforced or replaced before the next snow season begins at the end of October, when an exceptionally large snow load may compromise the panels. In total, the “high risk” and “critical” condition RAAC panels constitute less that 2.5% of the Science Centre’s overall roofs.

Engineers Rimkus performed a panel-by-panel assessment of the RAAC roof. The green shows low-risk sections of roof, whereas the red sections are recommended to be reinforced or replaced by the fall. If this is not possible, the engineers recommend restricting access to the areas directly below the affected roof sections.
In “Building A,” facing Don Valley Road, the roofs are directly over the Ontario Science Centre’s conference centre and part of its its entrance hall. The IMAX theatre and entrance are a different roof type that does not need repair, and the main floor lunch and locker areas are not on the top floor, so are also not affected by the recommendation for restricted access.

The remediation of these “high risk” panels is estimated to take at least three months per building—and floor areas directly beneath the high risk panels would “need to be treated as construction zones within the building,” according to the report.

However, this doesn’t mean closing the building entirely: it means erecting barrier walls to eliminate pedestrian traffic in the areas directly below the 2.5% of the roof panels being repaired or replaced. The hoarding would be similar to what’s currently present inside the ROM, where parts of the museum are undergoing renovation.

At the Ontario Science Centre, the construction would arguably affect visitors even less than at the ROM, because the RAAC panels do not exist above most key exhibition areas.

In the lowest and largest building, facing the Don Valley, the main exhibition spaces are in a part of the building with regular concrete panels on the roof—not the RAAC panels. Areas under the regular roof, which is not in need of repair, including the Weston Family Innovation Centre, AstraZeneca Human Edge, Living Earth, Science Arcade, Hot Zone, A Question of Truth, School Area Learning Centres, and the Valley Cafeteria

The main exhibition areas shown on this plan have standard concrete roofs. The only areas affected by the RAAC roofs, and which may require temporary/partial closure for proactive repairs, are the Rock Paper Science Hall and the Special Exhibitions Hall.

The highly popular Kidspark and the Space Hall—as well as the Rube Goldberg-esque machine outside of these areas—could also remain open, since they are not immediately beneath a roof, but one level down.

The IMAX theatre and entrance, as well, have a different roof type and could remain open with no danger.

There are some areas that would be more affected, but these are largely outside of the permanent exhibition areas. The report notes that the Science Centre’s in-house workshop would need to pause operations for the repairs to be completed, since that area includes large machinery that couldn’t be easily moved out of the way for repairs.

In “Building C,” on the valley floor, the main areas affected by a higher concentration of higher-risk RAAC roof panels include the Science Centre’s in-house workshop for fabricating exhibitions, a temporary exhibitions space, and the Rock Paper Science hall. The areas in grey towards the top of the plan—including the Weston Innovation Hall, AstroZeneca Human Edge, Science Arcade, and Valley Restaurant—are under a different, standard roof type. Note that this plan is flipped upside-down from the partial Ontario Science Centre exhibitions plan above.

The most notable temporary closure would be of the Great Hall, where special exhibitions are hosted; the special exhibition space at the lowest level may also need to be temporarily closed. From what is shown on the drawings, the Rock Paper Science hall—a space that is currently only sparsely populated with a handful of exhibits—is the only permanent exhibition area that may require temporary closure to accommodate repairs.

In the central section of the Science Centre (Building B), repairs are needed throughout the roof, including in the central Great Hall portion, which the engineers were not able to access, but presumed was in a similar state to the surrounding roofs. However, the report suggests that the repairs could be completed while only restricting access to the floor areas immediately below the roof. This would affect the special exhibitions in the great hall, but the recommendation suggests that the popular exhibition areas on the floor below—KidSpark and Space Hall—could remain open.

The Rimkus report acknowledges that getting the first wave of needed repairs done by October 31 may be challenging. So, it offers some alternate options for maintaining public safety. You could install temporary reinforcement for the panels, it says, or horizontal hoarding below the panels. The absolute safest option, it notes, would be to close the areas immediately below the less than 2.5% of roofs with high-risk panels, to stop people from walking in these areas.

Since the areas with high-risk panels are largely above non-exhibition areas, this means that even if there was a need to delay roof repairs past October 31, the Ontario Science Centre’s permanent exhibitions could remain safely open to the public.

In short, whether the roofs will be repaired or not, there is no material in the engineering report that calls for the complete closure of the Science Centre, either now or even by the October 31 deadline. Those repairs should be made, of course, presuming there is the intent to keep the building functional in some way in the future—but the idea that a life safety issue requires complete closure of the centre is false. The safety of staff and visitors can be ensured by simply sealing off the floor areas below less than 2.5% of the roof with construction hoarding, and completing the three-month-long repairs. If the repairs take longer than the fall, the construction hoarding can stay up, and this solution is judged by the engineers to “completely eliminate the risk to public or staff.”

There are no roofs needing repair directly above the key exhibition spaces—including the Weston Family Innovation Centre, AstraZeneca Human Edge, Living Earth, Science Arcade, Hot Zone, A Question of Truth, School Area Learning Centres, and the Valley Restaurant. Therefore, the report suggests, these areas can remain safely open, regardless of whether or not roof repairs are undertaken immediately.

The Ontario government has stated that the summer camps scheduled at the Ontario Science Centre will take place at a nearby school. It has also said that it is issuing an RFP for a temporary location for science programming, while it continues work on a new location for the Ontario Science Centre at Ontario Place. This new location for the science centre will be 45% of the size of the current Science Centre, and there is currently a call out for companies to build the project through a public-public partnership (P3), a process that is known for prioritizing cost savings over design quality.

As I have written before, the relocation of the Science Centre is based on a faulty business case. As the business case states, it was prepared “in response to the December 2021 direction to identify order of magnitude costing and capital requirements associated with relocating the OSC to the Ontario Place site and subsequent April 2022 direction to seek Stage Two (construction) approval for the project.” In other words, the provincial government had already determined, more than two years before any public announcement, that it was determined to relocate the Ontario Science Centre to Ontario Place. The business case was specifically constructed to justify this decision.

The drawings included with the engineers’ report indicate that Infrastructure Ontario had received progress updates about the roof assessment as early as January 12, 2024 and that it had a draft assessment report in hand on March 1, 2024.

Meanwhile, the timing of the sudden closure of the Ontario Science Centre on June 21 also seems to have been calculated, rather than resulting from a newly received report. Officials with Infrastructure Ontario said they had received the report detailing the building’s structural roof issues in the week of the announcement, and made the decision to close the building “as quickly as we could move.” However, the drawings included with the engineers’ report indicate that Infrastructure Ontario had received progress updates about Rimkus’s roof assessment as early as January 12, 2024, and that it had a draft assessment report in hand on March 1, 2024—almost four months before the June 21, 2024 announcement of the immediate closure.

The Ontario Science Centre’s Joint Health and Safety Committee (JHSC) will be contacting the Ministry of Labour that the report was not conducted legally: staff were not notified that the report was being prepared, that inspections were being made, or that there would be people on site.

Even though the province has stated that camps would be relocated, staff also say that there is no plan in place at the moment, and that they are scrambling to find accommodation for summer camps.


How to pay for repairing the Ontario Science Centre? Let’s start by using the money it’s taking to close it

The true cost of repairing the Ontario Science Centre is much, much less than what Infrastructure Ontario has been saying—and the proof is in its own documents

Cost of Ontario Science Centre temporary location exceeds cost of roof repairs

TSA issues open letter on Ontario Science Centre closure

Closing science centre unnecessary, says firm of architect who designed building

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