Money invested in house VS Resale?

I have been living in my place for 2 years. It is a log home and during this time frame I have spent $30,000. This includes a metal roof, 2 Propane firelaces, limestone boulders. I am redoing the logs this year and replacing 5 windows and adding new siding to the top half of my house. This will equall another $5000. I am doing all the work myself so labor is not an issue. There will be some savings in enrgy costs..but not enough to offset the cash I have put in already. My question is how much is too much to pour into a house? My family is very happy here and I hope the amount of money will decrease as I fix up the place. $30-40,000 on a new car is not unheard of so why do we get all upset over dumping money into a house. After 5 years a car is worth a third of what you spent. How much would a new roof. landscaping, siding and windows add to my place realistically? I am not counting my time..just materials? Is anyone else in this quandry?