buying an old house could be profitable, but risky

forget answering your another question about the old house.

theoretically, you have to understand the life of a house, after several rounds of rehab, the final destination of a property is demolition. That's for sure for 99% of the property.

Then the question is "how long"?

I have properties from new through 150 years. I also had properties which was forced to demolition. Beware of that, the final demolition could mean negative assets, because it's enforced by the government. I had a house which was demolioned by the government, and I was billed by the governemtn $43,000 for the demolition. The labor and dumpfill of trash are very expensive.

Understanding the process will help to estimate the value of an old house. Now you know it's a curve back to zero, therefore, there must be a maximum value, as you have already pointed out at 40 year old.

Therefore, the old house costs you less to buy, that's the good side. So the investment of old house is not the price of the house, but the maintaince and rehab fees. Also you should pay more attention to the policy. Now many cities are fighting fircely against vacancy, if your properties had been vacant for half year, it could be demolished by the goverment.

In one word, buying an old house could be very profitable, but also very risky.