Before sunrise each day, Aoife Diver, a teacher in Dublin, gets into her car and drives for up to 90 minutes from her uncle’s house to the opposite side of the Irish capital.

After school, it is back in the car for the reverse commute. On a recent evening, Ms. Diver, 25, sat in stop-and-go traffic, the red of the brake lights in front glowing through the windshield, as dusk turned to darkness.

It was not always like this. She used to share a house with five friends close to the school where she works in South Dublin. But when her rent and bills reached almost half of her monthly salary last year, she knew she had to move back in with family.

“There’s very little housing available, and what is available is way out of my reach,” she said. “Eventually, I probably will have to move somewhere else because I’m never going to be able to afford a house or an apartment on my own up in Dublin.”

The skyrocketing cost of private rentals has left many people struggling to afford housing in Dublin and other Irish cities, pushing some to move abroad and others to commute long distances. The crunch has left teachers and social workers priced out of the communities they serve, professional couples unable to buy homes and people on lower incomes fearing homelessness.