It's extremely difficult to say because you don't know what you're going to be in for until you take it apart. As you take it apart you discover more bits that seriously need doing. Then, there are other bits that aren't great but you could get away with leaving. However, you find yourself saying I've come this far so I might as well do that properly too'. It can snowball very easily
What condition is the bulkhead in? This is a major game changer in the amount of time and money needed for the job.
What condition is the bulkhead in? This is a major game changer in the amount of time and money needed for the job.