Work on the building was due to take place to enable children to use it
An investigation has been launched after a building within Arrasey Plantation was set alight.
Police believe it's a case of arson and happened over the past few days.
On social media, officers have described the situation as 'saddening'.
Anyone with information is asked to contact headquarters on 631 212.
Tynwald announces death of Douglas North MHK
Tributes paid to John Wannenburgh
Manx Utilities 'deeply saddened' by death of chairman
Wannenburgh praised for 'exceptional' leadership
"Tynwald will be a less colourful place without John" says president
Watterson describes Wannenburgh as 'devoted' to constituents
Douglas North MHK pays tribute to 'amazing friend'
Wannenburgh had 'biggest heart of anyone I've ever met' says Ashford