sauna problems: flashing water leaks, rotten wood & brick mortar dry failing

[mojo88]

Hi. There are alot of problems with this sauna. The metal chimney around the flashing outside has gaps and lets rain water inside and has started rotting the wood inside the sauna room. The brick mortar next to the sauna and water heater is like sand in some places. It looks like its going to collapse some day soon without intervention.

Basically I was given the task to fix this with my own initiative and wallet without much experience with this yet.

I have removed the heat shielding on the ceiling just above the sauna because when I got here it was just barely hanging there by 2 rusty nails.

I use the sauna but first heat the water and then when its hot I heat the sauna. It creates some heat around the base of the chimney and is a bit worrying about potential fire hazard. There should probably be more fire heat resistant material around those rotten parts.

Any advice where to start before it gets worse..