Hi Benson123# Patrick,
This is a grey area and it is largely a question of fact and degree in each case whether expenditure on a property leads to an improvement.
Please review the guidance at:
PIM2030 - Deductions: repairs: is it capital?.
To help determine if the expenditure is revenue or capital in nature.
Revenue expenses are set against the rental income.
Captial expenses are set against capital gains.
The expenditure can only be one or the other, not both.
Thank you.