If you go to see The 26-Storey Treehouse don't expect to see some massive, multi-level construction up there onstage.

Cast member Freya Pragt says audience goers will have to build most of that in their heads.

"I think the clever thing about the design is that so much of it is left up to the imagination," Pragt says of the treehouse.

"A lot of it is implied, because to build a set of 26 storeys and carry it around the country is a huge undertaking. So luckily our audience is children who have the most fertile imaginations of anybody.

"The kids are all for it. You can suggest something to them and they'll say 'yes of course, that's exactly what it is'."

Pragt plays Jill, the friend of treehouse-dwellers Andy and Terry.

And it's a special treehouse - it's got man-eating sharks in tanks and a 78-flavour ice-cream dispensing robot.

Jill, who can talk to animals, gets called into action to perform underwater surgery when one of the sharks gets sick after eating a pair of Terry's dirty underpants.

The play sticks very closely to the book written by Andy Griffiths and Terry Denton (yes, they are the same Andy and Terry from the play).

It's a popular book for so many kids which Pragt understands, as she was a fan of Griffiths' books when she was at school. So she wants to focus on ensuring the children have a great time at the live version of a favourite book.

"I try to connect with the kids and include them," she says.

"They're not great at watching as outsiders, they really want to get involved. So I find when performing for children and preparing to perform for them is to encourage them that it's an interactive experience and that it's not some kind of revered sit in silence and keep your hands in your lap thing. We want them to be involved. So there's a lot more playing out to the crowd and looking at kids directly and really encouraging them. We'd have them up on the stage if we could."

Since graduating from the Victorian College of the Arts in 2011, Pragt has been in front of quite a few grown-up audiences but a theatre full of children is a new experience.

"I've never done children's theatre before so it's a whole new learning curve for me," she says.

"I've found children as an audience are a lot more honest and not afraid to participate vocally throughout the show, which is always encouraged in the Treehouse plays. It's a whole new world for me and a really great adventure."

While The 26-Storey Treehouse is aimed squarely at the kids, Pragt says the cast also enjoys it when the grown-ups come along.

""It's really nice seeing the adults laugh at their kids laughing. We love it when the parents come along as well because it's fun to see their kids laughing and so engaged and the parents to get a kick out of the crassness and the silliness of it as well."