if it is a charitable inst. than same shall be amounted as revenue exp. because in case of Charitable inst. same kind of exp. needs to be done on continuous basis. But In case of Any other inst. it should be a capiotal exp. as interrior is something which org. does't change usually in a short intervals
Your query misses to specify as to the nature of use to which interiors of therented premises are put. Further, it also depends on the fact as to how are you going to pay for the use of the premises and the interiors. Is rent paid for both inclusive of use of everything or is it possible to separate the rent on the basis of use of interiors and rest of premises.
From your statement it appears that rent is being paid for the use of interiors. The same should be treated as revenue.
In case there is anything else that you want to know, please provide a more sanitized detail of your problem and then maybe we can give a more appropriate opinion.