Why your specification tool should not be a black box
Structural engineers need to verify every step of a calculation. If your specification tool hides the working, you cannot sign off the design with confidence. Here is why calculation transparency matters and what to look for.
The trust problem
You run a calculation. The software gives you a result. Green tick. Pass.
But what did it actually check? What assumptions did it make? What formula did it use for the combined loading interaction? What concrete condition did it assume?
If you cannot answer those questions, you are signing off a design you have not verified.
This is the black box problem. And it is more common than it should be in structural specification software.
What ‘black box’ means in practice
A black box tool takes your inputs and gives you an output without showing the steps in between. You get a utilisation ratio or a pass/fail, but not the calculation chain that produced it.
For most software, this is fine. You do not need to see the sorting algorithm behind your spreadsheet.
For structural engineering, it is not fine. The engineer signing off the design is professionally responsible for the result. ‘The software said it was okay’ is not a defence.
The consequences
Professional liability. If a design fails, the engineer is responsible, not the software vendor. Without visibility of the calculation, you cannot demonstrate due diligence.
Peer review. Another engineer checking your work needs to follow the calculation. If the tool does not show it, the reviewer has to repeat the entire calculation independently, which defeats the purpose of using the tool.
Audit trails. The Building Safety Act requires a Golden Thread of design information. A pass/fail result without the supporting calculation does not satisfy this requirement.
Error detection. Software has bugs. Data has errors. If you cannot see the intermediate steps, you cannot spot when something looks wrong. An experienced engineer can often sense when a result does not feel right, but only if they can see the working.
What transparency actually looks like
Calculation transparency is not just showing more numbers. It means showing the complete reasoning chain so an engineer can follow and verify each step.
The calculation chain
A transparent specification tool should show:
- Input parameters clearly stated, including which values were user-provided and which were derived
- Design standard clauses referenced at each step, so you can check the tool is applying the right rules
- Intermediate results for each failure mode, not just the governing case
- Formulae rendered clearly, not hidden behind variable names
- The governing failure mode and why it governs
- Utilisation ratios for every check, not just the worst case
What to look for
When evaluating a specification tool, ask:
- Can I see every formula used in the calculation?
- Can I trace a result back to the specific design standard clause?
- Can I see which failure mode governs and why?
- Can I export the full calculation, not just the summary?
- If I change one input, can I see exactly which results changed and why?
If the answer to any of these is no, you are relying on trust rather than verification.
The deterministic requirement
Transparency is necessary but not sufficient. The calculation also needs to be deterministic: the same inputs must always produce the same output.
This sounds obvious. But some tools introduce variability through:
- Optimisation algorithms that explore different solutions each run
- Rounding differences between internal and displayed values
- Version changes that alter results without clear documentation
- Server-side processing where the calculation environment is not controlled
A deterministic calculation means you can run it today, run it again in six months, and get the same result. This matters for compliance, for peer review, and for your own confidence in the design.
Why this matters more now
The Building Safety Act 2022 introduced the concept of a Golden Thread: a complete, traceable record of design decisions and compliance evidence throughout a building’s lifecycle.
For structural specifications, this means every design decision needs to be:
- Recorded with the full calculation, not just the result
- Traceable from specification back to calculation, and from calculation back to inputs
- Auditable by someone who was not involved in the original design
A black box tool cannot satisfy these requirements. If the calculation is hidden, the Golden Thread is broken.
How Clariti approaches this
We built Clariti around the principle that every calculation should be fully visible.
Every step is rendered with the complete formula. Every design standard clause is referenced. Every failure mode is checked and reported, not just the governing case. The calculation is deterministic: same inputs, same verified result, every time.
When you generate a specification in Clariti, it links directly to the calculation. The PDF report includes the full working, not a summary. An engineer reviewing the design can follow every step without needing to repeat the calculation.
This is not a feature. It is the foundation the platform is built on.
Try it yourself
Clariti helps you specify structural products in minutes with deterministic calculations you can verify step by step. Free for engineers and architects.