Improvements on former Private Residence

I am in the process of making some capital improvements to my former Private Residence, before selling it, which I believe will increase the sale value. In fact the improvements are actually needed to make the property sellable. The property was my Private Residence for 10 years and by the time of sale, will have been owned as my non Private Residence, for 10 years. When calculating the Capital Gain Private Residence Relief, should the improvements, be added to the base cost of the property and Private Residence Relief and the chargeable gain, be calculated on that figure, or should the improvements be deducted after the gain has been worked out on the base cost and Private Residence Relief applied?

Hi,
There is a capital gains calculator at:
Tax when you sell property, which will put the capital allowances in the correct place to calculate the gain, as well as the private residence relief due.  Capital allowances are deducted before working out the private residence relief on the gain.
Thank you.