First, make sure you're talking apples and apples w/your Plumber. See Construct A French Drain for a description of a French Drain.
Maybe he's talking about a clogged sump pump drain pipe. Maybe he's talking about a French Drain that 'runs' the perimeter of the foundation. Maybe, just MAYBE, you can save yourself a lot of $$$ by doing the following.
During the next sustained rainstorm, don your boots, raincoat, and umbrella, and do a COMPLETE walk around your home, looking UP at the roofline as well as at the ground. See if you can improve your drainage by improving the landscaping around your foundation. 1/4" per foot (for 3 feet) is the recommended MINIMUM slopage (and distance) you should have for drainage around your home. The more slopage (and the more distance), the better. (For example, 1" per foot for 3' is better than 1/4" per foot for 3' ...) Also, look to see if your gutters are leaking. Look to see if gutters are MISSING where water is running off of the roof. Be sure your downspouts are extended a MINIMUM of 3' from the foundation, and that water isn't running BACK towards the foundation. (We're back to minimum slopage and distances again ...) Once you install missing gutters, fix leaks, fix slopage, and extend your downspouts, if you still have water problems, you have more work to do.
My best to ya and hope this helps.
Jay J -Moderator
PS: God Bless America!
[This message has been edited by Jay J (edited May 28, 2003).]