Bog is useful when a tenant punches a hole in a door, you bog it , sand it and paint it.

gbwelly: It appears that the bog is still intact and the structure has given way.

neb: I just picked chunks of it out of the rot with a large screwdriver.

Why didn't you just pick out the rotten wood and fill the cavity with bog?

neb: This was one of the less rotted parts that had been bogged up...  In other areas there was almost nothing left of the surrounding wood. Cowboys, I tell ya...

Ahh, so it was a window surround,

well then... it was probably not even "structural bog" it might have been the more commonly used "cosmetic bog"

- you have got to watch those cowboys  they will always take the easiest option and using cheaper grade non structural bog is one of the biggies :) 

Ah, it looks like that window sill has had a dulux overhaul.

Some (simpler) people see the symptom as the problem, and are not the slightest bit concerned with the cause or the imminent reoccurrence

The painters doing my house loved a 2 part resin that would solve all the window sill problems because "it lasts for 20 years".

I followed it up by repairing the window rubbers to solve the leak.

On some of the older alu windows the reveals were untreated timber and the side in contact with the window wasn't sealed.  When the inevitable condensation occurred the timber absorbed water and rot started.

I have seen a bathroom window on an internal wall where the reveal was MDF.  Go figure.

Bung: In the bad old days the local timber yard would give me a can of the CCA Tanalising fluid. That stopped any rot that you might have missed. The other answer that worked was the boaties fall back, a 2 part resin that was thin enough to soak into any soft wood before setting.

MikeAqua:

On some of the older alu windows the reveals were untreated timber and the side in contact with the window wasn't sealed.  When the inevitable condensation occurred the timber absorbed water and rot started.