I had a full roof replacement last summer with a large Japanese Maple not three feet from the only place available to park the dumpster. The contractors built a plywood cage around/over my tree so that not even one leaf was touched. I also had new beds everywhere with tiny new annuals, and not even one was stepped on. Of course I had discussed my concerns with the owner before signing the contract and made sure reference to plant protection was in the contract. On the morning of the first day I met the crew with bagels and coffee and said "OK, everything you see here is of value to me. I know mistakes happen, but I am begging you to mind your feet and minimize collateral damage. To you it is just a tree- you break it, say "oops" and that's the end of it. For me the damage will have much more of an impact. You can call me crazy or obsessive and I won't care- just don't break my stuff!" I cannot recommend my guys highly enough- at the end of a huge job (total tear down and metal roofing installed) I saw them on their hands and knees combing through my beds looking for debris or dropped screws. After the fact we may have found 2 or 3 screws and that's it- no other damage whatsoever. Long winded way of saying anticipate these things, discuss them with those who have the power to affect their methods and speak directly to the crew.

The consensus in Georgia is to wait a couple of weeks and then prune what you know is dead. We got hit hard a week or two ago. My experience with Japanese maples is that they frequently have small dead branches that turn almost white and can be pruned. I would let nature take its course and wait a while. Its happened before and will happen again-the trees survive.

I'm glad your damage wasn't as severe as I thought. You've been given some good advice on pruning. I think you'll be surprised how it looks when it's done. On another note, I would not refer a company to anyone for an accident, especially if they felt bad about it. Accidents happen as we know just from the weather. I'd hate to count the times that I've accidentally stepped back on something or dropped something myself and broken a plant or limbs. Now if they didn't care that it happened it's a different story, but to possibly hurt someone's livelihood is a big step to take. Cher

One possibility would be sunscald. It's more common on southern facing sides of the trunk but can occur on west facing. It happens in the late winter or early spring and much less commonly in the fall. You can't rule out any older damage to the trunk that has now become visible either. Canker is also possible, however I don't see much there that makes me think that is likely. It appears you have good callous growth so the tree is healing over the wound. It is worth contacting your local Extension to be sure there is no disease.