The decisions that lock your structure

Nothing on a building project announces itself as final. Nobody tells you the layout is settled, or that the foundations were decided three weeks ago in a conversation about window sizes. The options stop being options, one at a time, while everyone is busy thinking about something else.

This is a map of when that happens. It is the same gauge we run inside our project intake, written out in full, and it is the honest answer to the question people ask us most: is it too late?

The five things that can still change

When we look at a house project, five things are either open, closing or already fixed.

• Layout. Where the rooms go, and which walls stay standing.
• Openings and spans. How wide the holes are, and therefore how hard the structure above them has to work.
• Structural approach. Steel, timber, masonry or some combination; whether a wall is replaced by a beam or left standing; where any posts land.
• Foundations. What goes in the ground, how deep, and how much concrete.
• Member sizes. The actual beams. The actual kilograms.

They close roughly in that order, and that order is the whole argument for calling early. The decisions taken first are the ones every later decision has to live with, and they are also the cheapest to revisit, because revisiting them costs a conversation rather than a redesign.

Our own gauge, drawn for this demo. Qualitative: it shows what is still worth revisiting, not a percentage or a price.

Key to the drawings

• Proposed Short dashes: work still to come.

Seven stages, and what each one shuts

1. 01

   Just an idea

   Everything is open, including whether the thing you want is the thing you should build. An hour of structural thinking here is worth more than a week of it later.

2. 02

   Talking to an architect

   Almost everything is still open. This is the best moment to call. A good architect and a structural engineer talking early tends to produce a simpler building, because the spans get chosen rather than inherited.

3. 03

   Drawings are being done

   Layout is closing. The rooms are where they are going to be, and the walls that survive have effectively been chosen. Openings, approach, foundations and sizes are all still open, which is most of the money.

4. 04

   Planning application in

   Layout is fixed: it is now on a public drawing with a reference number. Openings are closing, because the elevations show the glass. Everything structural under the skin is still ours to shape.

5. 05

   Planning granted

   Layout and openings are both fixed. The three decisions with the most steel in them, the structural approach, the foundations and the member sizes, are all still fully open. There is real work left to do.

6. 06

   Out to builders for prices

   The approach and the foundations are closing. Every change from here costs a re-quote as well as a redesign. Member sizes are open right up to the moment the steel is ordered.

7. 07

   On site

   Most decisions are made. We can still help, and quickly, usually with the things nobody expected: what is above that wall, what the trial hole found, what Building Control has asked for. Once the steel is ordered, the only thing left to save is your patience.

Why late costs more

Late changes are not expensive because anyone is being difficult. They are expensive because each decision has already paid for the ones underneath it. A beam one size too big is a line on an invoice. A foundation deeper than it needs is more digging, more concrete, more time, and a crew standing in a hole.

It works the other way too. Being early does not mean committing early. It means knowing, before the drawings harden, which parts of your idea are structurally cheap and which are expensive. That is the difference between a wish list and a buildable one.

Whenever you call, the design meets the Building Regulations, and we answer Building Control's questions on our calculations as part of the job. What changes with time is not whether it is safe. It is how much of it is still worth optimising.

Where you are today