Fair House Valuation

Good day, my wife and I will be filing for divorce shortly and need to know how to value our home.
We closed in December/2012 on a ~260,000 mortgage.
She moved out of our home in Feb/2013, I have paid all mortgage payments, bills, insurance, etc. since.
We are both on the mortgage and deed.
We owe ~240,000 on the mortgage, the home is currently valued at ~310,000.
I did not have the house appraised at any time in the interim.

I am working to refinance the house in my name only and would like to continue living there.
What is the fair value of the house, that we would then split and I buy her out of her portion of the uptick in value?

The only true way to determine the value of the house is to have it professionally appraised to determine the value as it existed on the date of separation. Her share would be half of the value, less the mortgage balance owed on that date.

Thanks for the information!

One follow up question, would I subtract out a realtor fee and any misc repairs that would have been needed to sell the house at that time from the appreciation value?

You can use additional fees such as the cost to sell or the cost of a refinance in your equation, but unless either of these two things are happening, you will likely have a hard time arguing for its inclusion during the negotiation process.