Repairing some steps - sharp or builders sand ? - Advice please

[poppak]

I will be doing a quick and dirty repair on some steps up through a woodland garden on a very steep slope. The steps are 18" Square 60mm slabs on risers of 3 bricks each. The bricks are not sitting on the lower slab, and some slabs have moved and they rock when using the steps.

Ultimately the whole thing will be re-built, but I need to make them safe by lifting the loose slabs, putting some mortar down, and re-laying the slab. I may need to rebuild some of the brick risers - wont know until I get to it.

Should I use sharp or builders sand, and will a 6:1 wet mix be OK ?

Any advice much appreciated.

Richard

[seanandruby]

Bricks, slabs etc: will always move on that type of woodland soil, very unstable. I would go for timber risers and strings, infilled with gravel, stone, self binding gravel etc: a more rustic look in a woodland setting.

[Tony McC]

Sean is, of course, correct - building over a woodland soil will only ever give short-term satisfaction before it moves, yet again.

However, if you have no option other than to use flags laid on brick risers, then I'd suggest the following:

Bricks laid onto concrete foundation based on sharp sand with coarse aggregate, say 1:2:4 (ST4) mix (see here)

Brickwork laid using 4:1 mortar based on a building sand with plasticiser

Flags bedded onto a 6:1 mortar based on a sharp sand (see here)

[poppak]

Perfect response, thanks guys.

Yes, the eventual re-build will use timber as described ( plus an additional 40M of 1 in 6 slope to make steps for !! ) , but there is so much to do to get general access safe. If I can just get the slab-rocking stopped for now, then I can move on to the collapsed dry stone retaining walls on the terraces, the patio for the early evening G&T, and then replacing the cast concrete steps at the front of the house.

Thanks again.

Richard

[seanandruby]

If the slabs are liftable and not built on with riser, then lift and re-lay for temp' fix, or lift and fill with some safe option fill. On steps safety first is top priority, temp', or permanent.