The rear part of the house is the tenement on larger houses it would hold the kitchen and servant quarters on smaller houses it would just be a single storey out house or kitchen. Mine has a tenement and has a second room above always with slopped roofs. Toilets would be in a privy at the end of the garden. The picture of back to back houses with yards is indication of the lower social standing of the housing. Larger houses actually had gardens as well and probably had cellars. The pattern of such houses is two beds up living room dinning room down and then the kitchen in the tenement.