Laying York stone slabs

[Pford75]

We are laying an area of paving in the garden and I have been shuttling around the country collecting York stone purchases from eBay. Now in need of advice on how best to lay them - we want to retain an aged look.

We have flags of various sizes and thicknesses. Since these are outside, do we lay them on a cement or concrete mix? Is grouting advisable and with what? Would people advise cutting slabs, and if so, how do you avoid lots of new looking sharp edges?

 

[johnandrew]

I know nothing about paving but the following seems to be a very good site with a wealth of information.

http://www.pavingexpert.com

John

 

[Lime]

What are the slabs going to be used for?
Part of a driveway where vehicles travel or just a walkway?
If just a walkway it is quite satisfactory to use sand to lay them on, no cement. Just make sure the ground/soil and sand is well consolidated before laying.
(A straight garden rake is ideal to level the sand.)

If cutting the slabs try to get the clean cut edges on the side of the path and not ajoining other slabs.
Sand by itself is fine to use as grout too.

Even if the paving stone is used for vehicles, as long as the subsoil is made very firm the same method can be used.
However much depends on the situation and condition of where the slabs are laid.
I'd avoid cement if I could.
It does not make laying any easier, and can damage the stone.

Don't use cement as some sort of replacement for proper preparation of the subsoil either.

 

[AMc]

FWIW I laid two patios of sandstone last summer thread here with a number of suggestions...
http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=11259&hilit=patio

One patio was up against the house I didn't want to use cement in case of damp and (as it's manufacture is less environmentally damaging than cement) I elected to use lime for both. That made a pallet delivery from Mike Wye financially sensible.

The stone was new and Bradstone recommended a solid mortar bed of 50mm over 65mm of consolidated hardcore.
Some of the slabs were thicker than others and the solid bed was clearly recommended over at the Paving Expert site - which reckoned the 5 dots approach belongs in the wild west
I had a large amount of rubble to dispose of so I broke that down to provide the hardcore base. It was probably over engineering but it suited my needs at the time. In retrospect I should have skipped the rubble and got a couple of tonnes of crushed hardcore as "a couple of days" work with a lump hammer took a couple of weeks
I was able to borrow a 'whacker plate' from a pal - I suspect that consolidating the subbase was more important than what it was made of.

I used 3:1 sharp to NHL5 mixed quite wet to which helped me to get good levels and a gentle run off over quite a large area.
I also grouted with the same mix using a pointing iron to push the remains of the mix in when I didn't have enough left to lay a whole slab.
I was a bit worried about some wet staining at the edges of the stone but after a few months this had completely gone and the initial 'whiteness' of the grout had weathered off.
I cut what I had to with a diamond wheel on a small grinder.

{quote="MW advice"]
1) Mortar Mix:
When laying the slabs there are 2 options, you could use a 2/1 (sharp washed pit sand / 1 Castle NHL 3.5) mix or you could use a 3/1 mix (sharp washed pit sand / 1 Castle NHL 5).

2) Quantity 37m2 @ 50mm deep:
If you are doing a 2/1 mix you will require 28 bags of NHL, and if you are doing a 3/1 mix then you will require 19bags of NHL.
[/quote]

 

[Pford75]

Thanks for the replies. The slabs will be for foot traffic only. Our challenge is that the area includes a well and some drainage pipes, so we are nervous about compaction with a whacker plate or similar, just in case of damage to pipes or well (the well shaft is apx. 3x3 ft but the area underneath is apx. 8x8 and 12 deep.

The previous paving had sunk considerably and upon lifting appears to have been laid on very fine sand which has washed away in areas. Our landscapers are advising a 10:1 mix of sharp sand and cement, over a crushed hardcore base. This seems fine having read the paving expert site.

Our preference is to butt joint the slabs and to use sharp sand to point (no mortar). Can anyone see a major problem with this?

 

[middi]

The reason why mortar based " bedding" is used is to facilitate the final level of the stone face. This practice is widespread by " modern builders" especially for internal use ( ie;- kitchens etc).
Whilst there is no harm done in bedding the stone in lime based mortar, exept more cost invoved, there is NO NEED whatsoever to lay yorkstone slabs on mortar bases.
In your situation ( foot traffic ) it would be most advisable to lay these on the existing scraped soil and consolidated base of hardcore aided by a layer of sand to adjust the level. The gaps between the stones should be adequate to compensate for any uneven dimensions of the stone up to 25mm if necessary. Fine gravel or sharp sand can be used to fill the gaps.
If the stones are completely square ( highly unlikely unless they are machine cut or high quality ones stolen from a cathedral somewhere) then these can be abutted without gaps.
Also, in your case. fast surface water dispersal is of importance,

Middi

 

[AMc]

FWIW one of the patios is over the main drain off the roof which goes into a tank like 3 way junction then off into the soakaway directly under the patio about a foot under the subbase. The pipe is ceramic and goes directly under where I "wacked". It still drains OK so I'm assuming I didn't damage it but with a well I would be slighty more concerned. The wacker does seem to "jiggle about" more than "hammer down".
Before the wacker arrived I was compacting with a fence post screwed to a block of scaffold plank. That did quite a good job of tamping down the layers and was a lot more gentle but a lot slower and more hard work. The sharp sand should also stop the hardcore moving.

I suspect that at 10:1 the cement is only lightly binding the sharp sand while the mix is wet? I'm guessing it would make the laying the slabs slightly easier than just sand, but it's your house so you should choose what is used

In the previous house we laid carpet stones - the paving equivalent of those mosaic tile sheets - they went on a 6:1 sharp to cement bed which was laid, leveled and compacted totally dry and used ground moisture to cure the cement after laying.

 

[Lime]

The reason why mortar based " bedding" is used is to facilitate the final level of the stone face. This practice is widespread by " modern builders" especially for internal use ( ie;- kitchens etc).
Whilst there is no harm done in bedding the stone in lime based mortar, exept more cost invoved, there is NO NEED whatsoever to lay yorkstone slabs on mortar bases.
In your situation ( foot traffic ) it would be most advisable to lay these on the existing scraped soil and consolidated base of hardcore aided by a layer of sand to adjust the level. The gaps between the stones should be adequate to compensate for any uneven dimensions of the stone up to 25mm if necessary. Fine gravel or sharp sand can be used to fill the gaps.
If the stones are completely square ( highly unlikely unless they are machine cut or high quality ones stolen from a cathedral somewhere) then these can be abutted without gaps.
Also, in your case. fast surface water dispersal is of importance,

Middi

Yes.
There is no need for major digging or cement of any sort.
What does need dealing with FIRST is the washing/leaching of soil and sand into the well by surface water.
A simple sheet of polythene under the entire paved area would solve the problem as long as run off was taken elsewhere and not allowed to seep into and under the sheet.
It is not difficult to lay slabs on thin flat compressed sand.
Adding cement complicates alteration and adjustments and makes laying much more difficult and time consuming IMO&E.