Raised sleeper bed... Timbers directly on ground?

[MisterBoy]

I'm building a large bed against a slope, so 3 sides of an 8m long bed, using sleepers.

I was wondering if one normally lays anything under the timber... Gravel or whatever? Or if it's just going to be touching soil so there's no point.

 

[RandomGrinch]

Hi,

I have seen this article mentioned a couple of times when talking about sleepers:
https://www.pavingexpert.com/featur08

...and it seems to recommend a concrete bed as best practice.

Personnaly, I have used a gravel bed with sand to allow drainage, and lined the soil side of the sleepers with a DPC, or membrane to keep the moisture off.
Probably not best practice, but after two years, so far so good!

...and the larger the bed, the more likely I would be to go with concrete!

 

[MisterBoy]

I've seen the concrete recommendation but it's not to my taste. Think I'll go with a layer of 20mm gravel... Might follow you on the membrane though I wonder if an impenetrable DPM would be better or some permeable weed membrane that'll let some moisture through but avoid direct soil contact.