Indian sandstone mortar depth

[markyyyyyy]

Hi,

Just before I lay some Indian sandstone, can I just check that these calculations are acceptable?

20mm slab
45mm mortar bed (compacted depth once slab installed/tapped down )
100mm compacted hardcore type 1

Cheers

 

[Wayners]

Yeah. That will do.
I find the 45mm about as thick as you want to go.

As for base 100mm is great. Some of mine is around 50mm but I'm not digging it out to remove the clay under..

Where I lifted slabs it can stay. I just removed the sand and cement and left the type 1

 

[markyyyyyy]

I’ll have way too much MOT left over so maybe I should compact MOT to leave a depth of 60mm (20mm slab and 40mm compacted mortar)

As a rough guide, will the mortar compact approx 20mm? Should I lay the mortar bed level with the top of the adjacent slab before putting a slab on and tapping into place?

I’m using 6:1 sharp sand:cement mix with a splash of plasticiser

 

[Mr Chibs]

It won't compact 20mm, if it's a full bed, probably only need to be around 5mm higher than the bottom of the first slab.
If you are unsure, lay a slab, tamp down, and pull it back up to see how much contact you've made with the back of the slab, if it's not enough add more bed, then you've got an idea of how much bed to put down.

I always prime the back of Indian with SBR & cement slurry.

I started laying with a float trowel, but now prefer to lay with bricklaying trowel.

HTH, Good luck