Wow! Cheers all, really appreciated. Diablo, yes, it?s an arch broadly like the pic you posted. I am the freeholder so that bit is less problematic at least. Condensation both in the room above the arch and on the inner brickwork of the arch is a real problem simply because of the cold so anything that adds to issues will need pondering. Will contemplate feasibility of taking everything out of the room to do from within. And yeah, appreciate we?ll be getting the sound/vibration through the building structure as well as via floor....but every little must help!