Small retaining oak sleeper area - damp proofing

[Temmy]

Hey folks,

I'm building a slightly elevated area in our garden using hardwood oak sleepers. The tops and visible sides will be treated in Textrol. It's two sleepers high.

When it comes to the side that will be filled in with soil, what would you recommend for damp proofing? A friend suggested a coat of BlackJack DPM should be fine, and indeed I've seen a few raised planter videos where they do that.

 

[Deleted member 174758]

Visqueen (black plastic DPM)

 

[^woody^]

Untreated oak will last longer than those metal brackets!
But if you think it's worth going for the 150 year life instead of 100 years untreated, then yes go for it.

I suspect that it's more of a case of lining the side to prevent the timber from looking damp, or looking unevenly damp, in which case a physical membrane such as polythene or DPC would be better than any coating - which will open and crack as the timber grain opens.
Don't trap moisture in though.