Hi, I have had a combi boiler installed under the stairs. The plasterboard ceiling was ripped out to accomodate the boiler and the vertical flue that shoots off at 90 degrees through the outside wall. I plan to fit a plywood ceiling (to be able to access the electrics above) but I'm not sure what clearance I shoud have above the boiler/flue. I don't have a great deal of space to play with by the way! Advice appreciated