The Brew Cabin

Posted: **Thu May 19, 2005 5:36 pm**

I am about to lay a natural stone patio of 45 square meters. I have already layed 4 inches of road stone for a sub base what options do I have next before carrying on with just corse grit sand, befpore laying the slabs?

Antonio

Wicked site chaps

Posted: **Fri May 20, 2005 3:59 pm**

Might be an idea if you have a read of this page
stone paving
Blimey it worked!

Posted: **Tue May 24, 2005 6:54 pm**

OK - I've read all the bumpf - and fantastically informative bunpf it is to - though it does go against a lot of the information you find on other sites and books.

Given that this site and forum is written by people who lived through paving hell, I am willing to go with it.

Can I clarify the following given that I am laying 36m2 of Natural Indian Sanstone paving in a random pattern for Patio use (no cars, pathways etc - just patio).

1) I do NOT need a subbase of hardcore, scalpings etc? IS THIS TRUE?
2) I do NOT need a membrane (plastic or otherwise) to prevent weeds etc.? IS THIS TRUE?
3) I DO need 50mm of Sharp Sand & Mortar in a 10:1 DRY mix? IS THIS TRUE?
4) DO I need to compact the sand & mortar prior to laying the slabs?

A simple yes or no will suffice - before I make a pig's ear of it.

Posted: **Wed May 25, 2005 9:29 am**

I'm not a paving expert, but from my recent experiences and years on this forum, here's my two penneth :

1) Yes this is true - You don't need a subbase for a light use patio unless the ground is very uneven or soft/soggy

2) Yes this is true - You don't need a DPM unless you have a known major problem with invasive weeds and even then it may not be worth it

3) Do you really mean 'mortar' and not 'cement'? - A 10:1 Sharp to Cement mix is known as a 'semi-dry' mix because the natural water content of the sharp sand starts the chemical reaction with the cement (if you have extremely dry sharp sand then hose it down prior to mixing). This is the preferred method over a full wet mix as there is less chance of staining your stone and most people find bedding the stones easier with this mix.

4) Yes, the bedding mix should be compacted but not a huge amount like a subbase should be (trampling by foot or patting down with a spade/shovel is ok for a patio I think). The top 5-10mm of the mix will be 'ruffled' to allow bedding of the flag.

Posted: **Wed May 25, 2005 11:00 am**

I have recently (as in the last few weeks) laid about 40mÂ² of Indian Sandstone. I fully agree with the answers to your first three questions.

My experience with laying on 50mm of 10:1 semi dry grit sand cement bedding mix went as follows.

For the first part (laying a circle) I trod the sand down, ruffled the top 10 - 15mm and then bedded the flags. Since then about half the flags have started to rock.

For the remainder of the patio I followed the 'instructions' on this site to the letter and layed the bedding mix uncompacted for each flag stone and then bedded each stone down to level (used a lump hammer on a short piece of 2"x2" wood as I don't have a pavers maul). Two weeks on and not one of the flags has shown any sign of rocking.

I would add the caveat that I think the circle (which has generally smaller pieces) got too much foot traffic from my rather excited two year old (and me) before the bedding had had a good 24 - 48 hours to set hard

Posted: **Wed May 25, 2005 11:38 am**

Hi Eeyore, yep the page on Laying Flags mentions compacting the bedding layer, but the Laying Riven page does not. My indian sandstone flags were very varied in depth and the bottoms ranged from very uneven to very very uneven! Therefore, for this type of stone each bed has to be prepared carefully to match the piece being layed (e.g. more bedding if the stone is thinner in parts - being careful not to create voids).

Maybe for natural/riven stone, compacting the bedding layer is not a strict requirement... but for pre-cast flags (which generally have a true bottom) this may be okay.

Posted: **Wed May 25, 2005 7:11 pm**

Thanks - that saves me the hire of a compactor and the purchase of any hardcore!

Posted: **Fri May 27, 2005 1:15 pm**

One last question - the board states that the "semi-dry" mix should be made up of a mixture of sharp sand, gravel and cement.

Can I just mix sharp sand and cement at a 10:1 ratio? - so not inlcude gravel?

Posted: **Fri May 27, 2005 2:34 pm**

I used a 10:1 mix of grit sand with cement. From what I can see grit sand is basically a coarse version of sharp sand. My local builders merchant sold it as 'class M' (if that means anything) Grit sand suitable for block paving.

Posted: **Sat May 28, 2005 6:29 pm**

I'm not sure that the methods I promote go against those promoted on other sites and books - I tend to be more thorough and specific, but every method I describe is "best practice" and backed up by almost 40 years onsite experience.

I know I have a reputation for slagging off spot-bedding, which is a popular method amongst eejits, jackanapes, cowboys, and other ne'er-do-wells, but that's becaue I know that spot-bedding is the single biggest structural reason for problems with flagging. If other sites and books go against the methods espoused on this site, then that's their lookout - it seems the original poster didn't have much confidence in what was said in these other sites and books, otherwise he wouldn't have ended up in The Brew Cabin!

The Brew Cabin

Laying natural stone