Okay, I'm going to say, I don't think Jack dies in the fire. I think something happens to him at the new fixer-upper house. That would explain the two house numbers. I think they're going to have to move into that house, super-quick, because this house burned down.
If you remember, when the kids are at someone else's house, they have the dog with them, and nobody knows where Kevin is (because he and Sophie went to the party in the woods). They aren't devastated because their dad died, their upset because they lost their house (IMHO--worth what you paid for it!). And it's a "day they'll always remember"--at first, because it's the last Superbowl before the kids leave for college, but later because it's their last night in the house they grew up in.