As the previous educators have noted, the house is destroyed by a fire after a tree branch goes through the kitchen window, knocking a bottle of cleaning solvent onto the stovetop.
What is really interesting about this description is how Bradbury humanizes the process. The death of the house follows a pattern that is similar to the death of a human body. When the fire reaches the attic, for example, Bradbury describes how the pumps are “shattered” into pieces. The description is reminiscent of the way that a skull might break, with the bone smashing into pieces.
From the attic, the fire moves from room to room, beginning with the upstairs bedrooms. This is a methodical process, just as a fire would move down each section of the human body.
To really emphasize the comparison between the death of a house and the death of a body, Bradbury talks about how the house shudders and how its “bared skeleton” is impacted by the heat:
Its wire, its nerves revealed as if a surgeon had torn the skin off to let the red veins and capillaries quiver in the scalded air.
This medical metaphor is also suggestive of what happened to the former residents of the house who died in the nuclear blast. This is, therefore, a way of highlighting the horrors of nuclear war without explicitly describing the gory deaths of these people.
Returning to the house, when the fire is finally over, only one wall remains, much like the two-dimensional shapes of people that were left behind by the blast. Thus, Bradbury uses the demise of the house to warn us against the use of nuclear weapons.