Thread: To Fill or not to Fill

My apologies if I have used the incorrect terms....

I have wood external stairs and there wasn't any booker rod put at the bottom of the stairs when it was built many years ago to keep the stringers from spreading. Over the years the stairs spread outwards and the paint has cracked where the stringer/step tread meet. Water has gotten down into the cracks and has slight rotted the timber on the tread.

I have installed some booker type rod to pull the stringers together at the base of the stairs. But I have a slight bit of rotten timber (5mm) next to the stringer. When it is dry I was intending to use Wood Hardener to fix up the timber (until I read some earlier posts). I am now thinking of using builders bog to stop any more water lying in the areas. I will then seal and paint.

Does this sound like the right approach or am I best to replace the stair treads. 5mm is the worst of the damage).

I have also noticed mold growing under the stairs, I have waterblasted the mold away but what can I do to stop it coming back.

Any ideas appreciated.

Judge4123