Block pavers on concrete - Information required

[parmi01]

Hi
I have a sloped drive which drops about 600mm over 6 metres and then levels out for a further 4 metres. As this will obviously need to take the weight of one/two cars, should I lay the blocks (200mm x 100mm x 50mm) on a Wet /dry mix concrete, and should I break the slope up with soldier course in the middle ( 3m) and at the bottom of the slope?
This also slopes towards the house, so I am planning on putting a drain in across the bottom of the slope, will this suffice as a soldier course?

Thanks for your help

[Tony McC]

Have you read the main website, in particular the pages comparing and contrasting rigid paving with flexible?

[parmi01]

Hi Tony
Yes I have, maybe I am just not grasping the content properly. I will read through again to see if the mist is any clearer.

[Peter in Essex]

Hi Tony
Congratulations on a fantastically informative site.
I have a question about block pavers on concrete as well. I have looked at the relevant sections of the site you suggest, but as a non-technical non-handyman, a lot of the info on the pages is beyond my grasp.
I am getting some quotes for block paving our front garden and drive from local contractors, and then discovered that my neighbour is having his done next week. A couple of the quotes are from people using traditional methods with the pavers laid on sand, ie a flexible base. But the guy doing our neighbour's drive uses a concrete base rather than hardcore. He says this makes the paving more weed-resistant and less likely to suffer from paving blocks sinking.
I am tempted to get him to do our side as well (it isn't a huge area - probably 56 square metres in all) because he can do it at the same time and with less noise and hassle than having ours done separately later. But I am not sure about the advantages, or disadvantages, of having a concrete base. The quotes are all in the same ball park, so cost is not the deciding factor for me.
Basically the driveway area will be about three cars' width and will only be used for parking cars. The garage is in front of the house, so the bit of garden between our garage and our neighbour's, which is currently crazy-paved, will not have any cars parked on it - or at least only rarely.
At the moment there is a soak-away drain in the middle of that. The guy doing the concrete base says he would simply cap that and put a fall on the paving from the front of the house, so that it drains off onto the pavement and grass verge (it is open plan, with no wall). But one of the other guys says he would keep the soak-away because the water needs to drain from that area. On the weeds front, he says that provided we look after the drive and keep soil off the cracks between the pavers we shouldn't get any come up.
I am confused as to which way to go. I have had a look at completed work done by the concrete guy and the other one just mentioned. Both have been recommended by people, and their work does look very good. The traditional method guy has been doing it locally for about 13 years, while the other one (who is a general builder as well) not quite so long.
Is a concrete base overkill, and is it a bad idea for a domestic garden and drive? Or is it simply a case of choosing whichever contractor will do the finish as we want and when we want, and never mind the method? If we choose the flexible method will that look odd butting up to a drive done over concrete - in other words, after a while is there likely to be any settlement of next door's drive, or ours? Both say their method is the best way, adding to the confusion!!
Can you give me your views, please?
Thanks, Peter

[Suggers]

Have you shown your neighbour this site, over a small libation of course, certainly a fantastic opportunity to work together and save cost.
At an early age, my old man drummed into me, in terms of building you can never beat nature, - all buildings move, all of the time - thus, the flexible approach will always win - forget the Titanic approach mate, it's old hat.
Some pix would be fun.
Good Luck.
ps - the old man still rues the day we gave up putting lime in the mortar to keep a flexible joint - now we just glue our houses together evidently, - "no wonder you got bleedin' cracks"
pps - Peter - just realised you've hijacked Michaels post!

[Tony McC]

I'll start with a brief word to Suggers: I'm with your owld fellah. We've become totally bloody obsessed with cement in the building trade while lime mortars are all but forgotten. The more I work with "traditional" paving materials (by which I mean stone flags, setts, cubes, etc.) the more I come to realise that lime mortars for both bedding and jointing are often a far better option than the cement-heavy materials we've been told to use over the passed 40 years or so. A month or so ago, I was looking at some paving around a well-known cathedral in northern England. The paving from 100 years ago, laid on cinders with lime mortar joints, is still serviceable, with very little settlement and no spalling. The paving re-laid just 10 years ago on huge dollops of concrete and 3:1 cement mortar jointing has cracked, shifted, spalled and looks a right bloody mess. Surely it can't just be coincidence?

Anyway, on to the concrete vs granular sub-base argument...

The use of concrete (or lean mix) sub-bases seems to be a phenomenon that started in the SE of Eng-er-land and is slowly spreading north and west. From what I hear, it seems that the use of a bound sub-base was taken up as a counter to the problem of channelisation (rutting) of residential driveways, and a way of checking one of the key selling points of PIC for the residential driveway market.

Now: it is true that some channelisation problems arise from a poor (or non-existent) sub-base. Either it's the wrong material (bloody road planings are common in Essex), or the wrong depth (25-50mm instead of 100-150mm), or incomplete consolidation (2 passses with a garden roller or a toy plate compactor instead of a solid pounding with a properly rated plate or a vibrating roller). So: using a bound sub-base would seem to counter this problem.

But there's also a second major cause of channelisation - loose edge courses. There are still far too many thick-as-pigshit contractors that lay the edge courses directly onto the sand bed to fit the body of the paving (and so minimise cutting-in), and then slap a trowelful of mortar on the outside edge, safe in the knowledge that it's unlikely to give way before the cheque has cleared. Once these pitiful constructions start to move (and they will start to move), they allow the blocks within the body of the pavement to move, which destroys the interlock, and so the whole pavement is free to settle due to point loading.

So - while a bound sub-base does overcome the problem of poor sub-base construction, it can't do anything about the shoddy practices used for edge courses, and therefore it can't guarantee to eliminate any possibility of rutting.

While I had my driveway company, we always used a granular (unbound) sub-base, and we had very, very few problems with settlement. On the handful of jobs where settlement did rear its ugly mush, we usually found there was an unforeseen problem with the sub-grade or the drainage. It's debatable whether a bound sub-base would have obviated these problems. Some would have been better with a lean-mix sub-base, while others would have been made worse by using such a material.

My current thinking is that it is better to stick with the granular sub-base unless there is good reason to suspect bad ground. I'm increasingly concerned that unscrupulous gangs are using lean mix sub-bases as a sales tactic and a ploy to cover up their lack of genuine skills. If a bound sub-base was the answer to all our problems, why aren't we using them on major commercial projects? The fact that the "big jobs" are continuing to rely on flexible, granular sub-bases says enough.

[Peter in Essex]

Thanks Suggers and Tony
As I write this, my neighbour's existing concrete drive is being dug up by the guy who is doing his block paving on a new concrete base. While it would have been handy to hae got him to continue over to ours and do it all at the same time, I decided to take your advice and go with the traditional method in the end.
Apart from the fact we won't be parking HGVs on the drive so we don't need such a solid base, I was concerned about water run-off as he was planning to cap the existing soak-away - while the guy we have chosen will incorporate it into the paving.
I was also concerned that if he did not include the correct spacers in the concrete base, it would crack and shift over time. In that event, a repair would be a nightmare with such an expanse of concrete below the pavers.
We will have to wait 4-5 weeks to have ours done, but I am happy to wait and get the job done as I want it. It will be interesting to see how the two drives wear over time. If there is any settlement on either side, I will post a follow-up message to let you know.
I don't think there is a problem with the ground here, Tony. This is Essex clay country (I live in Shoeburyness, just east of Southend), and all the fields around here have been stripped for brick-making over centuries. Actually, the local brickworks only closed last year because it could not compete with the mega producers. Shame, as the colour and quality of the bricks is fantastic.
One final quick question, please. I see that in another post someone was asking about the merits or otherwise of sealing a drive. I think he has concrete pavers, as opposed to block pavers like ours will be. My son's car leaks oil, and as the car is old the garage can't fix it. Obviously I don't want it spoiling the new drive. I will ensure he puts a rubber mat down, but there is still a risk that oil will drip onto the drive. Will sealing it stop oil from getting into the pavers and sand - and should I wait three months as you suggested for the other drive?
Thanks again
Peter

[Tony McC]

A quality sealant will oil-proof your paving, but some of the cheaper acrylics are lesse effective at preventing penetration (ooh err, mussus!).

Regardless of whether they are clay or concrete pavers, I'd still prefer to wait 3 months before applying a sealant. Problems tend to come to light in the first 4-12 weeks, so it makes sense to me to sit out that period before committing myself to a sealant.