Hello, I'm looking for advice with adding insulation to the inside of a sloping vaulted ceiling below loft level. The building is a barn conversion, originally converted in the 1980's. Currently the rafters are exposed and sit below a thin layer of solid insulation that has been painted on the inside. Above the insulation is what we believe to be a non-breathable roof felt then the tiles. Currently the noise level is high when it rains heavily, and we hope to help with both the noise reduction and also to make the room warmer by adding some kind of insulation between the rafters, then plastering over this. We have been advised that if we provide more insulation between the rafters, whether it be Celotex or a multi foil, we are likely to introduce interstitial condensation, as the structure (boarding and felt) will not allow vapour to escape. We would be looking at a major expense to remove the roof tiles, replace the felt and boarding with a vapour permeable underlay, install counter battens and then re-fixing the tiles. This will be outside of our budget. Does anyone have experience here and can anyone offer an alternative solution? All work to the pitched internal ceiling would be below the oft space, but as the vaulted ceiling is part of a high pitched roof, the tiles and roofline start almost at mid side wall height. Thank you for any suggestions.