Laying sandstone questions

[ahfix]

Hi

I've just ordered calibrated indian sandstone paving (https://www.naturalpaving.co.uk/flagsto ... e/lakeland) from a local merchant which will be delivered next week.

The patio is an L shape with the main section approx 8.4 x 2.4 meters and 1.5 x 3 meters. The sub-base has been prepared with a minimum 100mm type1 thoroughly compacted with a gradient. I then went over with a sprinkling of sharp sand to bind any areas where the type 1 was a a bit 'stoney' or fines had settled after compacting.

I've gone through the main site and read up on bedding methods. I was thinking of doing a compacted and screeded a dry mix bed @ 50mm using 6:1 sharp sand/cement. The screed method for calibrated natural stone is mentioned as is using a dry mix but not together. I am not sure if this combination is viable for sandstone. Could you please provide some guidance?

The reason for going down this route is I'm doing this on my own over a number of weekends so I'm thinking it would be easier for me to screed & compact a section at a time and lay the slabs and repeat the process. I would only screed out as much as I could lay that day.

Your help is appreciated

[DNgroundworks]

I wouldn't personally.

I prefer a wet 4:1 mix, nearly bricklaying wet and as thin as is practicable. SBR and cement slurry on the back of the flag tapped down to a string. I know the dry mix is recommended, and i have seen pictures of it being done but when i have attempted it every single flag always sounded hollow which for whatever reason the client didn't approve, me either really.

Anything other than yorkstone, kerbs, setts (or anything 'heavy') gets laid on wet mix.

Well it did, i don't do much now.

[packlam]

Hi

I've just ordered calibrated indian sandstone paving (https://www.naturalpaving.co.uk/flagsto ... e/lakeland) from a local merchant which will be delivered next week.

The patio is an L shape with the main section approx 8.4 x 2.4 meters and 1.5 x 3 meters. The sub-base has been prepared with a minimum 100mm type1 thoroughly compacted with a gradient. I then went over with a sprinkling of sharp sand to bind any areas where the type 1 was a a bit 'stoney' or fines had settled after compacting.

I've gone through the main site and read up on bedding methods. I was thinking of doing a compacted and screeded a dry mix bed @ 50mm using 6:1 sharp sand/cement. The screed method for calibrated natural stone is mentioned as is using a dry mix but not together. I am not sure if this combination is viable for sandstone. Could you please provide some guidance?

The reason for going down this route is I'm doing this on my own over a number of weekends so I'm thinking it would be easier for me to screed & compact a section at a time and lay the slabs and repeat the process. I would only screed out as much as I could lay that day.

Your help is appreciated

`Definitely not a dry mix. We've had ours laid on that and they are loose and sound hollow. Also watch the Natural Paving thickness. In the nine or ten packs we've had (don't ask...) the depths are hugely variable and the width varies by up to 10mm too!

[Tony McC]

Screeding for riven stone, even the calibrated stuff, is better suited to professionals able to judge the best way to deal with the variable surface profile of the flags. While the prepared bed may be perfect, and the flags all (allegedly) 22mm or whatever, humps and hollows on the surface of such flags means that not all flags are laid on the same plane, and some adjustment is often needed.

It's not that a screeded bed *can't* be used with riven stone, more that it may not be as straightforwards as you'd imagine.

And dry bedding is just not viable. A semi-dry is OK for professionals, able to cover the ground quickly and achieve a decent bond, but, for the overwhelming majority of DIYers, a moist mix is by far the best option..... https://www.pavingexpert.com/layflag3#slump

[ahfix]

Thanks for the feedback, I'll go with wet mix.

Any thoughts on an 8mm joint?

Just out of curiosity, other than potential movement could the slab be laid on sharp sand alone with bound edge? Before you throw your laptop at me, the only reason I ask is there is a path I want to lay and as I would like to have an extension built next year it might be useful to be able to lift the slabs to protect them (and then fix them properly after). That way I have a path I can use until then and the stone weathers evenly on the path and patio.


Keep up the good work.

[ahfix]

`Definitely not a dry mix. We've had ours laid on that and they are loose and sound hollow. Also watch the Natural Paving thickness. In the nine or ten packs we've had (don't ask...) the depths are hugely variable and the width varies by up to 10mm too!

Interestingly I've been on the phone with the building merchant, not happy with the quality of the slabs. Only unpacked a small number and I can see scrape marks and rust stains (from a saw?). The slabs are suppose to have chamfered edges but most of the small ones seem to have only 1 or 2 chamfered sides and the others are 'straight cuts' as if larger slabs have been broken down to make smaller ones.

ah

[Tony McC]

Apologies for being late to this - had all sorts of health issues with angina during the heatwave and now an arthritic knee that is driving me mad with pain.


There has been a spate of complaints about the quality of stone paving doing the rounds lately. I suspect a lot of it stems from the fact that, with now new product coming in from locked down India/china/Vietnam,/etc., stock of the good quality stuff has been plundered and even the best suppliers are now eyeing their 'seconds' or 'iffy' stock and wondering whether it's better to fulfill a customer's order or leave them with nowt.

I would suggest that, has you didn't pay for the paving in shonky pound notes, you should not be willing to accept shonky paving!