That's MY Church!

Central Heights Church made national headlines when a section of the sanctuary floor collapsed and sent 50-60 teens into the basement 12 feet below. I was in Abbotsford at the time and got a call from my friend around 1/2 hour after it happened. A few friends went down there to see what we could see and also to offer help if they needed it. But they had called every emergency crew in the area and they had the place under control.

We praise God that no one was killed.

Central Heights is MY church. I've been a faithful attender and member there for over 10 years. I moved to Victoria last fall but when I am in Abbotsford, you will find me at Central Heights on Sunday morning, just to the right of what is currently a gaping hole.

At the time of me writing this, there is no investigation results released yet and no engineering report. But I'm an engineer (albeit and Electrical Engineer), and perhaps I can offer a little church history and my best guess as to the cause.

Central Heights Church is of the Mennonite Brethren denomination. It is a mainstream protestant denomination (not to be confused with Old Order Mennonites). The types of services vary between churches, but for the most part, MBs have been known to be conservative in their services. In fact the early service at Central Heights sings almost exclusively hymns, and has no "rock and roll" type instruments such as drums, electric guitars and bass.

Over the years, a new generation has been replacing the old generation at Central Heights. The difference can be seen between the worship styles of the first and second services. The second service is much more lively and almost charismatic (we even have flag wavers now during the worship). Anyway, I would say that where we are now as a church is not where we were when the sanctuary was built in 1985.

In the time that I've been attending CHC, we have allowed worship bands to use/rent the sanctuary for concerts. Doxa had a weekly praise and worship night for several years, which was often packed out with young people, not unlike the Starfield concert. My friend and I snuck down into the basement under the sanctuary during one of the lively Doxa songs. We watched the ceiling as it flexed/bounced several inches. Looking back, I'm sure the Doxa crowd was using the floor beyond the designed limits.

Basically it comes down to this: When they designed the sanctuary for our conservative Christian church, no one was thinking "mosh pit".

The engineers probably designed for what would be considered the worst case loading. More specifically: the pastor has an alter call and the entire congregation comes down to the front. That is a reasonable maximum load to design for.

But this was a different kind of crowd. In a mosh pit the people are packed much more tightly than in an alter call. And what if the people suddenly start jumping around (in sync no less)? Those two factors combined is a different kind of load altogether. If enough people jump in unison, you suddenly run the risk of pounding the floor until it just breaks apart under the load. Another possibility is that you may hit the resonant frequency of the floor structure and essentially "double bounce" the floor (as you would on a trampoline). In either case, you end up with structural failure.

The section that collapsed was being held up by wooden trusses that ran between two main wooden support beams under the aisles of the sanctuary floor, hence the "cleanness" of the break in the floor. It is likely the trusses were connected to the beams using metal hangers which were nailed into the beams. The force of the moshing crowd likely sheared off the nails or simply broke a few truss hangers. Other trusses probably failed in quick succession due to the weight of the crowd.

This is a shot of the concert before the accident. Note the size and height of the speakers and the lighting truss that ended up on the floor.
Here is a closeup of the lighting truss.

I too find it amazing that no one was killed. But not because of the floor, but because of the way the lights and speakers came down on the crowd. Look at the way those speakers crushed the pew. It was a sold out concert with lots of people and little room to move. Someone could have easily ended up under that pile of speakers (and those things are HEAVY). Also, the lighting truss is strategically sitting right on top of two pews (see first photo). There are some important things to note here: 1. The truss is preventing the right pew from falling into the hole, thus preventing injury to people below. 2. Had the truss come down even 6" farther back, it would have hit people on the head who were in the row behind. 3. Had the truss come down slightly ahead of the pews, it would have hit people standing in the row in front of the pew. 4. Depending on the order of events (not sure), the floor collapse may have actually saved some people from getting hit by the lights and the truss. The fact that a lighting truss (with all those speakers) was able to fall that hard into the crowd that big and not kill anyone is a miracle in itself. There had to be a whole lot of strong guardian angels working that night.