mould on timber retaining wall

[lommel]

Help!
we built a small retaining wall using (untreated, but solid) oak sleepers (laid horizontally) a few years ago. The timber has a plastic damp proof membrane stapled to the back. This was to protect the back of the sleepers and prevent moisture in the soil from affecting the timber.
This year we have noticed an infestation of mould and mushroom growth appearing from the gaps and grain of the timbers.
Any advice on permanent solution(s)?

 

[freddiemercurystwin]

Don't build a retaining wall outside out of timber.

 

[conny]

The timber should have been pressure treated with preservative before using it as a retaining wall.
It hasn't helped that you have breached the 'membrane barrier' by stapling through it.

 

[JLondon]

I'm having a similar problem on 'treated' sleepers I built a retaining wall on.

I noticed some white 'looks like powder' spots, now I see its spread and looks more solid, and then even a bit green

I had a stack of off-cuts as well, when I looked through them, some were completely covered in white/green mould/mold

I'm looking for a solution as well - wondering if I need to take apart the whole wall and look for infestation and clean somehow???

Thanks
J