Construction is risky. For example, last month a tree fell on top of Parkview Mountain House. The tree was located upgradient from the house and, it was so big, that pieces of it actually landed across the street on our neighbor's property.
Thankfully, it didn't cause as much damage as it could have. It punctured the roof in a few places, but magically, the bay window that it landed on was perfectly fine. We also opened up the drywall around the window to inspect all of the structure.
Needless to say, we didn't have a line item in our budget for "trees that might fall on the house during construction." We also didn't have a line item to take down more trees behind the house, which is exactly what we decided to do after this happened. We called an arborist and asked them to fall anything that looked even remotely questionable. That ended up being 4 more trees.
We were not expecting this.
But this is why budgets have something called a construction contingency (although, we still have enough savings from some of our other contracts not to have to use it). In the end, we also learned something. If a tree falls in a forest and no one is around to hear it, the answer is -- yes -- it can still cost you a lot of money.