在你的句子中，the house the roof of which = the house whose roof 

    又如：The art museum whose garden is very beautiful will open next week. 那个有着非常漂亮的院子的美术馆下周将开馆。（这个句子可以改为：The art museum the garden of which is very beautiful will open next week. ）（摘自《外研社英汉多功能词典》2008年7月第1版）

Nobody wants the house the roof of which has fallen in.

参考译文：没有人想要屋顶倒塌/塌陷的房子。

为什么the house the roof,这名词中间不用连接词吗？

以上由of+关系代词 which引导的定语从句，在定语从句作定语

名词(1)=the root

名词(2)=the house

关系代词which=名词(2)

whose +名词(1)+the +名词(1)+of which=of which+the+名词(1)

(备注： 名词2为前面的先行词，即被定语从句修饰那个名词，名词1为名词2的所有拥有的东西。）

(1)Nobody wants the house the roof of which has fallen in.

(2)=Nobody wants the house whose roof has fallen in.

(3)=Nobody wants the house of which the roof has fallen in.

参考译文：没有人想要屋顶倒塌/塌陷的房子。

例如下面句子

他想要住在窗户朝南的那个房间

He wants to live in the room whose window faces south.

=He wants to live in the room of which the window faces south.

=He wants to live in the room the window of which faces south.