Ok - so the house was never inherited...Following is the primary publication fro basis determinationhttps://www.irs
.gov/pub/irs-pdf/p551.pdfpage 3 left columnConstructing assets
. If you build property
or have assets built for you, your expenses for this construction are part of your basis. Some of these expenses include the following costs.Land,Labor and materials,Architect's fees,Building permit charges,Payments to contractors,Payments for rental equipment, andInspection fees.NOTE - Do not include the value of your own labor, or any other labor you did not pay for, in the basis of any property you construct.I understand that it might be not a simple task to determine all these costs after 60 years - so do your best estimate and be reasonable..Then - we will talk about adjusted basis - you must usually make certain adjustments
to the basis of the property. The result of these adjustments to the basis is the adjusted basis.page 4 The following items increase the basis of property.The cost of extending utility service lines to the property;Impact fees;Legal fees, such as the cost of defending and perfecting title;Legal fees for obtaining a decrease in an assessment
levied against property to pay for local
improvements;Zoning costs; andThe capitalized value of a redeemable ground rent..See also Table
1 BasisIncreases to BasisCapital improvements:Putting an addition on your homeReplacing an entire roofPaving your drivewayInstalling central air conditioningRewiring your homeetc.So when you come up with the adjusted basis - we may estimate the gain.