A mortgages a piece of land to B and later on builds a house thereon, which of the following conditions is applicable?

As per s.70 of the Transfer of Property Act, 1882  which talks about the same illustration and the concept of accessions to property. S. 70. Accession to mortgaged property.— If, after the date of a mortgage, any accession is made to the mortgaged property, the mortgagee, in the absence of a contract to the contrary, shall, for the purposes of the security, be entitled to such accession. Illustrations   (b) A mortgages a certain plot of building land to B and afterwards erects a house on the plot. For the purposes of his security, B is entitled to the house as well as the plot.