How can I check the levels?

Morning all.

I'm about to have a crack at laying a natural stone patio. Never attempted anything remotely like this before, so fingers crossed. I won't ask for general advice as I'm sure there's plenty of 'guides' out there.

One thing I do need advice on though is how i can check I'm laying it all level. Thing is, as it's natural stone, the surface is very uneven (which I like), so a spirit level isn't really much use (is it?).

Any pointers?

if you are not using a spirit level what else are you going to use?

if its natural stone, you need to allow for the thickest stone when you dig the "hole" (the finsihed level must be below the DPC level. lets say 2 inches below)

the thickest slab you have is 3 inches, the thinest is 1 inch (i just made these figures up you understand) so the hole must be 3 inches deep + the depth of the mortar bed.


lay the thickest slab you can find first, and use this as you level.

the thinner slabs will have a thicker mortar bed to raise them to the height of the thickest slab (since you have already laid the thickest slab)

you use a sprit level to check is each slab level, how ever they should not be 100% level you should have a slight slope on each slab so that the slop runs away from the house, this is so rain will not run towards, but away from the house.

The above is not 100% correct but is a guide, I am sure if i have any errors others will point it out

bear in mind the hole as i called it is the area in which the slabs are to be when finished.

set your string lines to your levels or falls then follow your lines, if you have a slab that has a high lump, lay it so the lump is a little above the line
but the common surface in flat to the line, any with real big lumps, lay these close to wall, out of walk ways so you don't leave trips, or use
them for cuts.

it is recommended that any slabs/concrete/tiles you put down are at least 150mm(6")below the dpc line because of splash.

with natural stone, as you say you will get some big variations. You need to avoid any differences bigger than 10mm, as it can be a trip hazard. It depends on teh size of the patio you are laying, but i use a string line and a 6 foot spirit level. With the spirit level you can still get a fairly indication, and you need to occasionally step back and get your eye down to ground level to check it. Remeber that its not a perfectly flat slab, as with many concrete ones, so variations in the stone is expected.

Thanks for all the input guys, much appreciated.

Patio size is 7m x 2.5m, and is the other end of a sloped garden (slope away from house) so no worried about the DPC, but thanks for that pointer. The stone I have looks pretty good actually, all quite thick 30mm+.

In terms of lines, I guess I just lay many of them out across the area to be covered? Almost like a grid of lines?

Thanks again