How does an engineer know if an existing wood building has serious structural problems? We make educated guesses about the strength of existing buildings based on our experience and on what we see. The same type of structural evaluation can help a contractor too. If you think the way an engineer thinks, you'll spot problems early. You'll know why you're putting in those extra joists. And on buildings that are in really bad shape, you'll be prepared to deal with change orders or structural collapse. When you have a question about the structural capacity of a wood member, you're trying to find out two things: • What is the current strength of that member? (This is so you