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Posted: Mon May 12, 2008 8:42 pm
by newbuyer17
Following on from my previous posts and the advice I have been given here, I am now in a position to start laying the bedding layer and slabs.
I'll be laying stonemarket yorkstone riven, which I'm assured are uniform thickness.
My current area is as below:
http://kjpublic.dynalias.com/patio4/IMG_4823.JPG
(Try to ignore the grumpy looking bloke who had been digging all day on the hottest day of the year so far 
The wooden baton shows where the tiles will lay - with approx 1-2" of bedding layer underneath, with a fall of approx 1:50
I now have two things I'm unsure of:
Q1.
whether to use a semi-dry bedding layer or a moist one. Semi Dry seems easier to me, but I'm worried about how much give there will be for levelling the slabs. I'm also (despite reading the main site page) still a little confused about exactly where it drags its moisture and how long it takes to harden fully - 8 hours is quoted.
The other option I guess is the moist mix, which sounds more hassle and is maybe difficult to get the right consistency, but is maybe more forgiving with levels and I can understand how it gets the moisture to harden. Is there a rough guide for how much water approx goes in this mix? What is the working life of this mix?
Which would be best for someone who has never done this work before?
Q2.
This question may also have some bearing on Q1 above. I'm struggling with time at present so don't think I can do this all at one go. What are the implications of doing this work a bit at a time?
I will hopefully be starting at the weekend, but then may have to leave it a week or so before doing any more. Maybe only half laid? Maybe not grouted? It depends on my progress. Is this a problem or can I take my time over several weeks? Do I need to cover with polythene to protect from the weather?
I'm a little worried about the bedding layer being washed away, especially with semi-dry mix?
Thanks in advance
Posted: Mon May 12, 2008 9:40 pm
by Rich H
Lets start with terminology first, at the risk of being a pedant. These are slabs or flags not tiles that you are laying and, when laid, you will point the paving not grout the tiling 
How much water depends on a few things, e.g. the weather conditions, the soil moisture, the sand moisture but, most importantly, the key question is the bedding method. I'm not sure I hold with the 'uniform thickness' statements that manufacturers make. They may be designed to be a uniform thickness but I'll bet my beloved Kubota that they won't all be.
If, however, you want to take their word for it and you are more fortunate than me then you may want to lay the slabs on a screed bed, in which case you only need enough water to prevent the mix from being dry. You should be able to squash a handful in the palm of your hand and it stay together. Any drier and it may not cure, any wetter and it will be a real bugger to screed.
My advice is based on a sharp sand - cement mix.
The moisture comes from the ground and the air (ever noticed how the grass is all wet in the mornings?) so it will cure, provided it doesn't dry out before it gets a chance. In this weather, you need more water than usual.
You may well find it easier to individually bed the slabs. Screeding is not the easiest thing to do properly and, unless I'm laying pavers or council slabs, I will always individually bed.
If you opt for this route then you will want it wetter. In this weather I'd have it wet enough that it doesn't dry flow anymore and that lumps consolidate without encouragement. Roughly, that's the best part of a bucket of water in the mixer in this weather when the sand has been quietly drying out in the sun.
The mix will be workable for as long as it takes - a barrow will do 3-4 slabs and so even if you are doing that many an hour the mix will be fine.
Don't worry about doing a bit at a time. The best way is to lay it all in one go and then point it right away to bond the pointing mix to the bedding course, but this has it's downside though as it's easy to tip a slab in the process of pointing. Many of the jobs we do require a week or more of paving before we even think about pointing. It's not unusual for people to lay a few square metres each weekend until it's done.
Posted: Wed May 14, 2008 11:33 am
by newbuyer17
Thanks.
I'd have much preferrred screed it dry, especially as I'll be working on my own rather than having someone to mix. The appeal of mixing a load of dry bedding and putting a large area down before laying stones was very appealing.
However, you seem to be saying that even a semi-dry mix should have water added to it anyway so I dont suppose it matter so much. The main site quotes 'little or no water' - but you seem to be suggesting enough water for what I'd have thought was nearer a moist mix? Or have I misunderstood?
Part of the reason I went for the stonemarket yorkstone was so I could screed. If I'm gonna indivudually bed is there any proper stone worth looking at in the same price bracket ~22 per sqm?
Good news re doing this work over a few weekends though as that will definitely be the way I'll have to do it. Does it need to be covered during this period?
Also, one thing I've not found on the site is about weather? What sort of weather conditions can (and can't) you lay slabs? Obviously torrential rain is out but is light rain OK, or do you need a dry day?
Thanks Again
Posted: Wed May 14, 2008 5:58 pm
by Rich H
You need just as many mixes for screeding as you do for individual bedding, and trying to screed for the first time on your own would, take it from me, be a nightmare.
Fer gawd's sake don't choose the slab type based on the laying method! That's the tail wagging the dog. Individual bedding is not difficult, if you are methodical and patient.
I personally think that the paving you've chosen is horrible. But that's purely subjective. However, I think it's so awful that the patio I finished last month using it (customer choice) didn't even get the usual photography session. Professional job, IMHO, but ghastly, bright yellow, obviously fake slabs.
As LLL has said in a reply to a different thread, you can buy beautiful and good quality natural stone from a supplier like GlobalStone which makes York Riven look like something out of Terry & June.
Yes, laying natural slabs is a bit more tricky, but you would soon get into the swing of it.
Now, concerning the moisture of the mix.
Sharp sand is usually left sitting in a yard in all weathers, soaking up copious amounts of water and only releasing it very gradually. In all but the warmest weather, a screeding mix can be made up without any water being added. If the sand has dried out, though, it becomes dusty and too dry to allow the cement to cure.
If you are individually bedding, a semi-dry mix would NORMALLY have about half a bucket of water in the mixer, together with 12 shovels of sharp and 3 of cement (opinions vary on the cement quantity but I've always been happy with 4:1 so won't change now). But it's been bone dry, hot and sunny for two weeks. The sand is much drier than normal so we're putting in a whole bucket of water to the mix. Your sand may be wetter, or it may be drier.
The important thing is that it is a) moist enough to cure the cement, i.e. not so dry that it can't be bound together in you hand, and b) dry enough so that it isn't soggy or a slurry, which will make your slabs 'float' and impossible to level.
There are some good photo's on Tony's main site which should give you the idea, for example:
Posted: Thu May 15, 2008 9:24 am
by newbuyer17
Thanks very much - really helpful.
I know what you mean re the slabs, but I'm trying to do this on a budget. The patio area we are doing will hopefully be demolished in a few years to make way for an extension, so we dont want to spend too much on it.
I've also reused as much as I can in terms of the wall etc to keep costs down, and its very different to how I would do it from scratch for a 'permanent' feature. It also has an ugly concrete path next to it, so it almost seems a waste to put nice stuff down.
But if the price difference is as low as the other thread suggests I'll look into it. Sadly my nearest Globalstone dealer is miles away though.
I've been round most of the local builders merchants and not really got anything decent - will raise another thread on any other local stockists to try.
Thanks for the info on the mix, which has now cleared things up for me.
Just one more thing that I need clearing for once and for all - can I do this in mild rain, and does it need to be covered?
Many thanks
Posted: Thu May 15, 2008 5:21 pm
by Rich H
You can do it all in light rain except the pointing. The slabs need to be dry for this if you want to avoid staining them.
