Wooden sleepers - should I put any fabric / damp proofing?

[ey143]

We need to build a sort of retaining wall against for a drive way which has been created by lowering the level of the ground which has now exposed the roots of a hedge in a side bed. It was suggested we use wooden sleepers instead of concrete foundation and a wall as this might damage the roots and eventually lead to cracks.

If I do buy 2.4m lengths of wooden sleepers, I think they come untreated. What short of treatment should I put on there and if this will be holding back earth at a height of 0.5m in the front garden, should I allow the soil to back up to the sleeper or should I put some sort of membrane there to stop the sleeper from rotting over time?

 

[AronSearle]

Buy them pressure treated with a copper organic treatment ("tantalised") to use class 4, ground contact, or buy a durable hardwood.

Brush or spray on treatments will not penetrate the timber to anything like the level required for ground contact use.

You will probably want a geotextile membrane, it allows water through (to stop water "damming up"), but isolates the timber from the soil.

 

[ey143]

Thanks. I have some 50m of black geotextile roll left. But why not damp proof the inner side - wouldn't that be better to stop it rotting?

Have you come across the timeless range sleepers from BSW - brown treated and sand blasted for decorative effect but I think 1 level below the class 4 that you refer to. Jewsons and trivis Perkins sells them.

 

[AronSearle]

Thanks. I have some 50m of black geotextile roll left. But why not damp proof the inner side - wouldn't that be better to stop it rotting?

Don't know.

Yes preventing moisture to the back face of the sleepers will improve their durability, but a damp impermeable barrier may allow water to build up, where will it go?

And the base of the sleepers will still be in ground contact, and that is where they will fail first anyway.

Have you come across the timeless range sleepers from BSW - brown treated and sand blasted for decorative effect but I think 1 level below the class 4 that you refer to. Jewsons and trivis Perkins sells them.

Tanatone (tanalith E) treatment is suitable for ground contact, but you need to check if they have been given the right level of treatment for ground use.

Otherwise they will decay in an unneceptably short time.