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Comment by semi-extrinsic | Hacker News Reader

It's really crazy how much there is that you don't think about up front if you've never built a house.

My first build (this summer) was a playhouse for the kids, 8 square meters single story. I built it mostly like you would a real house, omitting a few details (like insulation between inner and outer walls, since it's not heated anyway). I ended up with a budget overrun of 40% and spent close to twice the number of hours I estimated up front. It turned out really nice though.

If you're thinking about building a house, I would definitely recommend doing a playhouse or a shed first.

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I just finished pressure-washing and painting a deck for some friends. Simple, right?

I estimated 20 hours, with another 4-8 of uncertainty. The job took 43 hours. So >100% overrun on my best-case estimate, >50% over my worst-case. If you don't have experience, it isn't just estimating the time that's hard, it's hard to estimate the uncertainty too. And I'd done a couple of decks before, just never any with as much railing or a second story.

I nth everybody else's suggestion to take on a couple simpler projects first. If you've never painted, paint something non-trivial. Then build a playhouse.

>budget overrun of 40% and spent close to twice the number of hours I estimated up front

Sounds typical for construction.

Needed more practice in construction estimating, which is yet another discipline that you wouldn’t immediately think of when someone says “build a house.”

A friend of a friend runs a pipeline construction company (think the people that would actually build Keystone XL or the likes) and he has a team of estimators that run all the numbers on a given project and come up with a budget. He then double checks their numbers by chartering a helicopter and flying the route with an an old construction foreman, who basically eyeballs the thing and and does some mental math. Apparently it was uncanny how often the two estimates were within 10% of each other, but that the old guy eyeballing the thing had saved him on a number of occasions by recognizing issues/costs that the estimators had missed...

After spending his entire career in construction, one of the last jobs my dad had before retiring was in preparing bids for proposals. The company wanted people with lots of experience in the bidding process. Not just on-budget, on-schedule, but people that had been through over-budget, behind-schedule so that they knew what to be aware of as potential pit falls.

When I was in college one of the big promises of BIM was "we'll have information rich models that will make estimating easier and more accurate!"

I'm not directly involved in that process in-industry (ended up in light fixture manufacturing), but my impression is that BIM models are usually good enough to kick out a set of drawings, but you wouldn't want to count on any information that you pull out of it electronically being accurate.

So you still have "contractor to verify quantity" notes on everything, and presumably someone going through the drawing figuring out how many "Type F 2x4' troffers" and how many faucets and how many of every other little detail that will take money or time.

It's a pretty intensive process, but given the amounts of money at stake if you screw it up, hugely important to get right.

or for software development :)

Software development is more like - couple hundred percent over spec in time and cost, code base is a mess, almost nobody uses it and finally, after a couple of years, management changes and the new mgmt calls a spade a spade and terminates the project.

At least that's often the case in huge organizations trying to do crazily ambitious projects (esp. given their general incompetence). I tend to consult on such shitstorms because it pays well. The scars are for life though...

that's is way I started with a dog house before even building a shed.

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