mortar mix for slabs

[Notch7]

Ive got some sand stone slabs to lay on concrete, what mix do I need for the mortar bed and pointing?

Ive read differing views on using builders sand, sharp sand or a mix of both

eg: 4:1:1 Sharp:Soft:Cement for bed and

2:1:1 Soft:Sharp:Cement mortar mix for jointing

TIA

 

[noseall]

Sharp sand (concrete sand, screed sand grit sand etc) is standard. We have in the past fattened it up with the odd shovel of soft building sand but this can lead to colour problems when gauging future mixes.

We used to point as we laid, by using the bedding mix as the joint material the fill and strike as the day wore on.

Now we retro-point with Geo-fix or similar.

 

[23vc]

Sorry to hijack but got mine to do soon, again with sandstone of mixed sizes. So far I’ve got the sub base thrown down and tamped but not whackered. Next stage is to whack and get the falls right as much as poss on the base.
When laying the slabs, is it best to run a string line to get the height/fall of the first row right, then revert to using a spirit level for the rest of it? Or do you carry on using a line for the whole lot in one direction or both directions? Which I can see as being a right fiddle

 

[Ian H]

I used 4:1 grit sand:cement for mine, then 5:1 once the cement was running out. They are all stuck solid.

The level worked ok but a few were very riven on the top so had different levels within the same slab. Looks ok though but haven’t pointed them yet.

 

[noseall]

Sorry to hijack but got mine to do soon, again with sandstone of mixed sizes. So far I’ve got the sub base thrown down and tamped but not whackered. Next stage is to whack and get the falls right as much as poss on the base.
When laying the slabs, is it best to run a string line to get the height/fall of the first row right, then revert to using a spirit level for the rest of it? Or do you carry on using a line for the whole lot in one direction or both directions? Which I can see as being a right fiddle

I use a line for falls and level out laterally (using a 1.2m level) from the line. I sneak up or down with the level where necessary. The art of presenting a decent patio is not to have too much fall and to keep the 'trend' of fall the same throughout.

 

[23vc]

So you just pull the line across once (say for the row nearest the house) and do all the rest with the level?

 

[noseall]

So you just pull the line across once (say for the row nearest the house) and do all the rest with the level?

Yes, pretty much. Sometimes you have to twist a patio so you generally can only line in one direction.