This is a nightmare. We have a 100mm pre-cast flu (exceptionally shallow apparently). We have now found a 90mm inset gas fire and want to fit the hearth/surround and mantel before getting the gas fire fitted.
Will we need to pack out the surround to give it more depth? Obviously the surround will have a little depth (about 20mm) but how will we go about packing it out if we need to?
We are way out of our depth on this and getting little help from any direction (fire company or gas fitter). Any advice from anyone who knows about this kind of thing please?