Safety Case Reports

Ok. So I've been reading, re-reading, typing and re-typing to try and make sense of it all and just when I'm at the point of putting it down for a bit... a 7 storey building jumps out at me yesterday and pulls me back down the rabbit hole. Damn thing.

So I'd nearly forgotten all about the Building Safety Act and various supporting documents. It was on the back burner. And then yesterday I walked onto site to review a potential +1 airspace scheme and have a look at the existing building.

Now I did have a quick look at the thing before I went and in my head I had 4 maybe 5 storeys with the idea of adding one on. Only to find out once I'd got on site that I'd missed a storey, plus the sneaky little basement below. It was 7 storeys in total?!

In its defence, the building was pristine. No cracks, no movement, no signs of any remedial work, all existing features, probably pushing 70+ years old easily (not checked yet), masonry construction with concrete slab floors, a timber roof and not a vertical tie in sight! She was awesome (I gave props to the maintenance guys too), but I felt bad walking away because I know come October when the high risk building assessments kick in... she's going to cause arguments.

Structurally she doesn't comply with current requirements. So vertical and horizontal ties are going to be mentioned. Possibly leaving it there as the main recommendation and potentially scaring the bejesus out of the existing tenants who now suddenly live in an 'at risk structure'.

Now. I've been reading:

• IStructE. Manual for the systematic risk assessment of high-risk structures against disproportionate collapse.
• HSE. Principles and guidelines to assist HSE in its judgement that duty-holders reduced risk ALARP.
• HSE. Assessing compliance with the law in individual cases and the use of good practice.
• HSE. Policy and guidance on reducing risks ALARP in design.
• HSE. Principles for Cost Benefit Analysis, CBA, in support of ALARP decision.
• HSE. CBA checklist.
• CPNI. Review of robustness.

Now loop back through and read that all again, plus all the other stuff the IStructE website points you towards in regards to Safety Case reports and you'll get a sense of where I'm at with this right now.

It was kinda making sense? Did a CBA, made a bit more sense, risk assessment growing on me, think its a good idea but needs work and then... hello non conforming 7 storeys which made me think about it all again.

I'm happy to admit I've not really done or had the need to understand risk assessments in my working career. They've been reserved most typically for Class 3 buildings which I've never been part of, but I suspect my experience mirrors that of most of the industry and can see this being a steep learning curve for most (including myself).

My main worry is that this becomes a paper exercise and there's no practical application. Or engineers either mis-use them or don't use them at all.

I think having the CBA provides a good baseline from which to inform the decisions, especially in non-compliant structures. but it almost needs a holistic view of the building (rather than with just structural goggles on) to look at all the risks the building is exposed to.

I think that's where the risk assessment is beneficial. Yes your building is at risk of collapse, but has been for 'x' amount of years already, its in good condition (visual condition survey), nothing is moving, there are other hazards out there (not just gas explosions) and based on all that, if an accidental event were to happen, the area of collapse could be substantial or severe (beyond current recommended limits). But the cost (time, resource and money) is 'x' to make it compliant, or.... we can manage the risks and reduce them ALARP - further than what you've been living with at present?

I think its going to be hard not to scare the hell out the residents when these buildings get re-classified.

RISK is going to be a big word for the industry. I've always thought disproportionate collapse was all about risk rather than any one solution. Easily done in new structures, less so in existing, and understanding the ALARP process and gross disproportion, consequence classes and where to draw that line in all of that is still going to involve a degree of engineering judgement.

The arguments aren't going to stop (in regards to retrofitting existing structures), but I think the risk assessment is a useful tool (ammo so to speak) to back decisions up with. The next step will be educating clients, tenants and anyone else within the industry as to best practice - which might still take a while to iron out.

I think we're still about 2 months away from being confident and comfortable with this. But the pieces are beginning to fit and make sense now. And ultimately... every building is still going to be different.