Huge hole in tree

[Gawains]

I'm building a tree house and put up a platform in the beginning of winter (away from the bark and sealed). It all seemed fine, until recently a large hole appeared beneath the platform:

View attachment 283541

I don't know if the woodpecker was thinking of moving in, or looking for bugs, but I can't really see any sign of infection except for this weird growth:

View attachment 283542

The tree had leaves in the fall and looked healthy enough. I hope I didn't mess up the tree

Can anyone here offer any advice as I'm clueless......

 

[Pelorus]

Listen to the woodpecker, cause it is telling you to relocate the treehouse to a tree that isn't decayed.

 

[Gawains]

Listen to the woodpecker, cause it is telling you to relocate the treehouse to a tree that isn't decayed.

Thanks, I guess its a good job the woodpecker got pecking or I wouldn't have known!