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 ho

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.