Construction
The designer questioned years later
That was calculated eight years ago on certain data and certain criteria. Today somebody asks about it, and only what you filed exists.
You signed a design, it was built, and years passed. Today a question arrives: an extension, a change of use, an incident, a review. **Whoever asks does not want to know whether you worked well: they want to know on what data and on what criteria that was decided**, and the answer is not in the design you delivered but in what sits behind it.
What gets asked and where the answer lives
| The question | Where the answer lives | If it was not archived |
|---|---|---|
| What was designed? | In the delivered design | It usually exists |
| On what input data? | In the annexes and studies | **It is lost first** |
| What criteria were applied? | In the calculation, not the drawing | It cannot be deduced |
| **What was actually built?** | **In the site changes** | **It rarely returns to the designer** |
Important
**What is lost first is not the design: it is the input data.** The delivered design survives because copies sit in several places. What disappears is the ground investigation they gave you, the flow figures you were handed, the assumption confirmed by email — everything that reached you from outside and on which the calculation rests. And it is exactly what is needed, years later, to explain why what was decided was decided.
What to archive with ten years in mind
- 1
The input data and who supplied it
With dates. The calculation rests on it, and it was not yours.
- 2
The criteria and rules applied
With their version: they change, and what applied then applied.
- 3
What was modified during construction
It is what separates you from what was actually built.
- 4
And which version is definitive
With several circulating, the question will always be which.
Watch out
The specific risk in this position is **being asked about something built differently from how you designed it**. It happens often, almost always for sound reasons taken on site, and it does not always come back to the designer. Years later the question reaches whoever signed, not whoever decided the change. Having on file what was modified, who decided it and when you were told —or that you were not— is the difference between explaining and carrying it.
Worth knowing
For how long project documentation must be retained, what liability reaches the designer and over what periods **is determined by the applicable rules, and settled by your professional body or adviser**. Here we cover the organisational part: what to archive in order to explain a technical decision a decade later.
›How long must it be kept?
Longer than the project lasts, and your adviser settles the exact period.
›Should I keep data that others gave me?
Especially that. It is the basis of the calculation and it is not yours.
›What if it was built differently from the design?
Archive what changed and what you were told. That is what places you.
A real case
The situation
Questions arrive about a project from eight years ago.
What you do
- Keeps the complete file with its date
What you get
It is answered from the archive, not from memory.
The situation
The input data supplied by others can no longer be found.
What you do
- Stores what was received from third parties with the project
What you get
The basis of the calculation still exists.
The situation
Several versions circulate and nobody knows which was built.
What you do
- Keeps versions with dates instead of replacing them
What you get
You can say what applied at each moment.
The situation
Something was changed on site and never reached the designer.
What you do
- Records what was communicated and when
What you get
Each party's position is documented.
The situation
The file lives on the computer of whoever signed it.
What you do
- Stores projects outside personal machines
What you get
One person leaving does not take the archive.
The situation
Documentation must go to a third party without over-disclosing.
What you do
- Controls which documents are shared and with whom
What you get
What was asked for is handed over, not what sat beside it.
This article answers
- how long to keep project calculations
- asked about a project from years ago
- which version of the design was built
- design documentation and site changes