The number of homeless children living in temporary accommodation across England has soared by 37% in recent years.
Local government leaders warned the increase amounted to an "unsustainable" average of 906 extra children every month in a period when housing costs have trebled.
Councils are providing temporary shelter for around 120,540 children with their families - an increase of 32,650 (37%) since 2014, the Local Government Association (LGA) said.
"When councils are having to house the equivalent of an extra secondary school's worth of pupils every month, and the net cost for councils of funding for temporary accommodation has tripled in the last three years, it's clear the current situation is unsustainable for councils, and disruptive for families," said Martin Tett, the LGA's housing spokesman.
The LGA said councils need to be able to build more "genuinely affordable" homes and "take steps to adapt welfare reforms" to help families into permanent accommodation.
The association warned temporary accommodation can hinder parents' employment and health along with their children's ability to focus at school and form friendships.
Anne Baxendale, director of campaigns and policy at Shelter, called on the government to abandon its freeze on housing benefit and build "decent homes" that lower-income families can afford.
"Every day we speak to families desperate to escape the dingy, cramped hostel room they're forced to live in, for weeks if not months, as overstretched councils can't find them anywhere else," she said.
"The situation is getting worse as the lack of affordable homes and welfare cuts bite deeper. The Government has the tools to break this cycle of heartache and homelessness."
The government said the number of children living in temporary accommodation was down from a peak in 2006 but said "any increase in the number of homeless families is always a concern".
A spokesperson for the Department for Communities and Local Government said it is investing £550 million to help tackle the issue and added the new Homelessness Reduction Act would help "individuals and families get the help they need earlier, stopping them becoming homeless in the first place".