Does the nouns of underground room add on to the price of the house? ...
Answers: I'm not a home builder or anything but I watch a ton of those design shows on the Home and Garden canal and everything I've ever seen indicates a finished vault adds helpfulness to your property.
Especially if it's finished with indistinct paint/carpet and has a bathroom - race are all roughly speaking having a bathroom downstairs.
No. Once you prefer to sell, confer on everything alone except for a little cleaning. Location of the property is what sell. New owners want what they want.