Schools in Toronto's Willowdale neighbourhood have a crowding problem thanks to a so-called vertical boom that has seen the area's population density skyrocket.

There are more than 100 condos along Yonge Street between Finch and Sheppard avenues, all built after 2003.

That explosion of new residences means 900 students have to be turned away from schools such as McKee Public School despite being within walking distance.

Even then, McKee has 750 students — 100 more than it's designed for.

The Toronto District School Board changed its population boundaries on Wednesday, meaning those 100 students will have to transfer from McKee when the new school year begins.

In the meantime, the school has converted two storage rooms with no windows or ventilation into classrooms, and uses a corner of the library for another. The school has two lunch periods and assemblies have to be held in shifts.

"There is no other open space left," said principal Cheryl Patterson. "We use our staff room as a music room."

'Can't take any more kids'

TDSB trustee Mari Rutkus said Tuesday that they have no choice. "The population is still growing. We just physically can't take any more kids."

Even if 100 children transfer to another school, McKee will still need two more portable classrooms in its yard, she said.

Rutka said one solution may be for Toronto to follow the lead of other cities where schools are built directly into condominium projects.