Why does building work always take twice as long as the estimated time?

[Hertsmum78]

This is a genuine question, not meant in a goady way.

We're currently having building work done. The estimate given to us as to how long it would take was 4 weeks, it will take 8. I never really believed it would take 4, and it hasn't been too troublesome, so this hasn't stressed me out too much, but I'm interested in the fact that this always happens, and why it does.

Do builders always give an optimistic timeline because they're trying to win the job? Or do they genuinely believe in their original timeline and get surprised every time? Do they know they're not being 100% honest?

Personally, I would absolutely love it if just once a builder would say to me 'I'm aiming for 4 weeks but being realistic it might be as long as 8 weeks'. I would much prefer people to under-promise and over deliver than vice versa. And if any builder ever did this to me, I would recommend them across the land as the best builder I'd ever worked with for this reason alone!

So why does no-one ever just be honest and realistic?

Because builders are men and can’t multi task and talk shite 90% of the time. My lovely husband and lovely brother always completely under estimate how long things will take.

@HardworkSendHelp I do actually wonder if this might play a part... I can tell that at every stage when I ask our builder about timings, he just hasn't quite thought everything through in a logical manner. But surely he would still remember all the other times he'd done this job, and said it would take him 4 weeks... and then it actually took him 8?

I think that builders in general feel it's better to give a reasonable estimate of time so as not to discourage their customers .
In an Ideal world where they're not dependent on other suppliers or contractors to come through with their supplies this could be a reasonable estimate.
In my experience it's not the builders themselves that are slow it's that they are waiting on other supplies to be delivered and especially these days that can take a long time.
Oh very experienced project manager will be able to slot in other customers while waiting for supplies to be delivered to another job.
Having said that, my own DH is a cabinet maker and his estimates are always way off base when he does anything for us!

Yes I get that they’re being optimistic and maybe different customers are different but personally I’d rather be told, for example ‘4 weeks is the absolute best case scenario, but delays with materials and suppliers could stretch it out to as much as 8.’

Surely most people would prefer to be given all the info so they can plan?!