Phil, everyone has said everything that needs to be said, you know that there need to be more expansion joints and you could encounter a multitude of other problems along the way. I have a theory, that you are never remembered and thanked for the good work you do, you only get remembered for the bad jobs, even if it no fault of your own.
You seriously want to be stressing over this?
Life is to short for headaches, and this could be a migraine in the making.
Do the right thing politely decline.
Lynn
It is a well known statistic in the customer services industry that if you have a good experience with a supplier you will tell between 5 and 7 people. If you have a bad experience you will tell between 17 and 25 people..... We humans are a negative sort generally and apparently love a good old moan.....