Work began last week in Endcliffe Park three months later than originally scheduled. The delay means the playground will be closed for the second successive summer.

Last year children were unable to use the equipment after floods damaged the safety surface and in 2006 the playing field was out of use for months during excavations for a new drainage system.

Martine Welsh, who often takes her two-year-old granddaughter to the park, said: "I cannot for the life of me understand the logic of commencing these renovations at the beginning of the school summer holidays.

"The park is a free day out for many families who make a whole day of it with picnics, barbecues and organised games. Particularly during the current economic climate, it's a godsend for parents unable to afford expensive activities such as theme parks and zoos.

"Once the work is complete in October, the playground will be fantastic but why couldn't this work have been started in March – or even March next year – and then it would have been ready for the summer?"

A Fulwood parent agreed: "Could somebody please tell us why it has been decided to start the three-month project the very week that the kids break up from school? I really do wonder what level of IQ is required to become a decision-maker at Sheffield City Council these days..."

Madeleine Thomas, chair of the Friends' group which spearheaded the campaign to raise nearly £300,000 in funding for the project, admitted that the timing was not ideal but said work had gone ahead in the hope of completing it during the dryer summer weather.

Meanwhile park café manager Nick Oodian has come up with his own play scheme to keep young visitors happy and, he hopes, encourage their parents to continue using the park.

He and boss Ashley Charlesworth have splashed out on two space-age awnings and a stock of outdoor toys and games.

"The timing of the work has affected business considerably," said Nick. "This time last year the rain was an issue, now a lot of mothers have said they're not going to come to the park because of the noise and the mess and because there's nothing for the kids to play on.

"We're a community café and we're trying to help by providing toys and games – and the tents act as a sunshade as well as a rain shelter.

"It's a considerable outlay for us and we're as angry as the parents are but it's the council's decision."

Coun Shaffaq Mohammed, Cabinet member for Climate Change and Local Environment, said: "It is unfortunate that the playground will not be available for children during the summer holidays, but it is important that these exciting improvements are carried out at this time of the year when the weather is fine and other options are available.

"We consulted on this with the Friends of Endcliffe Park, who worked so hard to raise the funds for the project, and a wide range of activities have been organised to cover the loss.''