Six feet is probably okay, but I would plant it 8ft. from the center of the plant to the house to be safe. Although this tree is narrow, it isn't small, consequently its roots are not constricted. Black and white spruce roots were used by Native Americans to make a sinewy string, because of the root's strong but flexible characteristics. So you should be able to plant it a little closer to foundations compared to other trees of comparable size.
