Plant and Machinery Allowances (PMA): buildings and structures: ceilings
Normally suspended ceilings and acoustic tiles are not plant. They are part of the building Ceilings are in item 1 of the list at CA22010.
There was a case, Hampton v Fortes Autogrill Ltd 53TC691, where the company claimed capital allowances on false ceilings in a restaurant. The claim was refused. The ceilings’ only function was to conceal service pipes, wiring etc. They were not apparatus with which the company carried on its trade of running a restaurant.
Accept that a suspended ceiling is plant if it forms an integral part of a heating and ventilation system. For example, it may form the fourth side of a duct or channel through which stale air is extracted for treatment or treated air is discharged.
Another case that involved a ceiling was an Australian case - ICI of Australia v CIR 1ATR450. The firm installed special sound absorbing ceilings in its office buildings. The ceilings consisted of acoustic tiles supported by metal frameworks attached by rods to the concrete floor above. The tiles were removable. The Courts found that they were not plant. They were part of the premises in which the company carried on its trade.