Help would be appreciated please. A partnership rents a factory and has incurred costs in installing a mezzanine floor for office use. Am I correct that the build costs( floor, window,electrics etc) are treated as improvements to leasehold property and only allowable against any capital gain on disposal of the lease? There is also a cost for soundproofing the floor as there is a noisy machine underneath and clients were worried about health and safety for office staff. Is this allowable (capital allowances?) or is it part of the lease improvement?