Any expenditure on integral features within a building has to be included in a separate pool upon which only 8{af331c3cb52abe27a47f1f5b71fb5068c938efb8d5a4e6cddc7f2780f48bb99c} Writing Down Allowance is obtained, rather than at the rate of 18{af331c3cb52abe27a47f1f5b71fb5068c938efb8d5a4e6cddc7f2780f48bb99c} allowance on any fixtures that are not integral features.

Included in this category for integral features is any expenditure that is incurred on repairs, where either the repair cost exceeds 50{af331c3cb52abe27a47f1f5b71fb5068c938efb8d5a4e6cddc7f2780f48bb99c} of the replacement cost of the integral feature, or if the total expenditure on the integral feature over the last twelve months exceeded 50{af331c3cb52abe27a47f1f5b71fb5068c938efb8d5a4e6cddc7f2780f48bb99c} of the replacement cost.

So, what are included in Integral Features that warrant such treatment?

They include:-
Lifts, Escalators and Moving Walkways
Cold Water Systems
Water Heating Systems
Ventilation Systems, Air Cooling, Air Purification
Floors and Ceilings comprised in Water Heating Systems, Ventilation Systems etc
Electrical and Lighting Systems

Many of these costs will be hidden within the purchase price of a building.  If they can be identified then the allowances can be claimed.  You may need the assistance of a specialised surveyor to do this.