House saw water leaking from his ceiling and hit it with his cane, causing a collapse.
He called Fernando to prepare a repair estimate for the insurance company. However, Fernando said that there was no sign that the pipes had corroded. Instead, it appeared they had been put under stress and pulled down. He told House his insurance wouldn't cover it and gave him a quote to repair the damage.
In order to try to get around it, House started a small fire in his kitchen, which was a covered risk under the policy, and told Fernando the fire had damaged the pipes, which now had to be replaced. Fernando agreed, but told House that the fire had damaged his neighbor's pipes, not the pipe that had sagged and broken.
House eventually bribed Fernando to put in a false claim, even though the amount of the bribe was larger than the amount of the damage.
Later, House was using his bathtub pipes to support his weight as he lowered himself into his tub and realized it was the repeated stress of this maneuver that had caused his pipes to sag.