I HAVE YET TO MEET A RENOVATOR WHO KNOWS WHAT HOME FEATURES ADD some form of resale value to the subject property before we can get to the ARV we first need to know the resale value of each amenity of the house based on a list of factors to be consider that may affect the potential returns rather those returns break even with the cost negative returns or in some cases positive returns when going to resale your renovated property construction project

I'm no expert. I'm fairly new and inexperienced. However my dad is interested in flipping rehabs so I've been researching it. I've come across questions like yours. The answer that is typically given is it depends on the market, the conditions of the individual house and what features comparable houses in the area have, which is why it may be hard for you to get a contractor to answer that question. From the different podcasts, articles and Q&A's on BP, the general theme is that there is no cut and dry list of features guaranteed to positively impact the resale value of a home. 

The example that comes up is putting expensive finishes on a house when all the other houses in the entire neighbor either don't have those finishes or the area as a whole doesn't have high home appraisals. Or worse doing everything right and then the market conditions change as a whole.

Some examples list changing the floor plan or adding a bedroom or bathroom to be good ways increase value. Even then what value is added as an estimate seems to hinge on comparable houses in that market.

When my dad gets rehab estimates, he is getting a list of improvements needed to make the property he has comparable to the other properties that were recently sold at market value. I could be wrong, but he doesn't add up individual improvements by Dollar amount and expect that amount to factor into the ARV. He starts with comps for the area, what homes have recently been sold for, what other houses are for sale and then makes a list of the features and finishes they have. He compares that list with the property he wants to rehab, gets a few estimates from contractors and then calculates his ARV and All in cost from there. He'll even go to open houses and browse houses that are for sale off the MLS just to see what styles are popular and what other sellers are asking for.

Anyone is free and welcome to correct me if I'm wrong or have misunderstood the concept. That's just my observation so far.