The Enchanted Barn by Grace Livingston Hill

The Hollisters, a bright, spirited, wholesome family, are compelled to move into the country. After many efforts to secure a home, Shirley, eldest of the Hollisters, contrives a way out by renting a magnificent old stone barn at a ridiculously low price, transforming it into a house. The owner of the barn is not an ordinary landlord, as you will see, for he is a young man with fine ideals, and he is not content with establishing Shirley and her family in the quaintly beautiful old place, but makes the world a much happier place to live in for all of them.