What's this  "6 tonnes of hardcore and Type 1"? It's Type 1 you need, not 'hardcore' which could be anything.

Anyway, once the sub-base is in and compacted, it can be left for as long as you like before laying the paving. It won't come to any harm as long as you don't let it get full of mud or soil.

For years and years I've been banging on that the Home Improvement Industry needs some form of regulation, so that only accredited, genuinely-skilled, fully-insured, tax-registered individuals, partnerships and companies can trade in the industry. Obviously, my main concern is for the Paving industry, but the same could and should apply to double glazing, roofing, painting & decorating etc...

It is the fact that this is such a free and unregulated industry, with access to large handfuls of untraceable cash, which attracts the cowboys, the rogues and the thieves. There are some moves by individual Local Authorities to make life more difficult for the unscrupulous and unskilled, and they are welcome moves, but they are flea-bites on an elephant - what is really needed is certifiable regulation through a scheme of registration and assessment, and until that comes about, we will continue to hear horror stories such as yours.  

Any luck with Trading Standards?

Make a full list of each and every defect, and, if possible, take photo's of the problems so that they are all fully documented. Give the contractor 7 days to respond with their plan of action, and make it clear that if they fail to respond, you will authorise remedial work to be carried out by a competent contractor at their expense. Send it recorded delivery, and from this point on, keep all discussions on paper. Don't fall into the telephone promise trap, where they keep fobbing you off with worthless verbal promises that never materialise but which they can deny as you have no verifiable record of the discussion. If they call, record the call (after informing them of you doing so, naturally!) or insist that they make all proposals in writing.

You could also ask TS to check on their VAT registration and their Employers and Public Liability Insurance, just to put the wind up them!  

Good luck!

I can't follow your second paragraph - where does this 75mm layer come in to it? Are you talking about laying the sub-base in 2 layers, each 75mm deep? If so, then you're doubling the work to no real benefit as a decent vib plate will easily consolidate 150mm thickness in one go (that's several passes, not one single pass), but, if you want to do 2 layers @ 75mm, then there's nowt wrong with it.

1. - excavate and dispose
2. - lay sub-base and compact
3. - scratch out sub-base as required to accommodate edgings
4. - lay edging and haunch
5. - lay bedding, compact and screed
6. - lay rest of paving and finish

Formwork isn't essential for this type of work, but you can use it if you want.

Does that make sense?

...and then, when you're ready, you can backfill over the spread of the sub-base and at the back of the kerb with your topsoil.

There is a table of comparative densities at the bottom of the Aggregates page

Assuming it is the pipe, then the best thing to do is to cover the trench with a geo-membrane, allowing at least a metre of spread to each side, if possible. Terram 1000 is probably the best 'all-purpose' geo-membrane to get hold of, and will be fine in a situation such as this.

I'm not sure as to the function of the 2 ICs - are they silt traps?

An IC is used on any type of drain for inspection and access. A silt trap is used only on Surface water or, more commonly, Land Drainage systems, to reduced the particulate load. Since the advent of permeable membranes, silt traps have become less essential, and are now most commonly encountered as 'settlement lagoons' on large highway schemes.

A Ped roller will be doing well if it compacts 250mm depth. A single drum roller is good for about 150mm of granular material, but you really need a double drum vibrating roller for anything more than that. And you'll definitely need a plate compactor for consolidating the blocks - you could use the roller for compacting the sand bed, but a plate is much better.

With clay pavers, it's a good idea to use a rubber sole on the base of the plate to prevent spalling. It's not a major problem, but, if you have to hire in, try and get one with the removable sole - take it off for consolidating aggregates, and fit it back when you come to hammering down the pavers.

Good luck!

Given that it is such a small project, with no vehicular traffic and very narrow paths, you could actually get away with laying everything on a 75-100mm bed of concrete, or the 10:1 bedding mix I espouse for patio paving.

I like the Probst splitters, purely because of the quality, but I also have an Errut hydraulic model that we used for stone slabs and kerbs, and about 3 or 4 of the Birchwood models which are cheap and cheerful, as they say. Belle have started manufacturing a tiny little thing that is great for small jobs or repairs when you need to split a dozen or so blocks, but IMHO it would become tiring on larger projects.

Have a look on the Tools links page for contact details.

The recommendation for a 2-5mm joint is standard to all flexible pavement blocks, and most, if not all, manufacturrs now incorporate spacer lugs on the sides of their blocks, so the 2-5mm joint includes the spacer lugs and is not an additional spacing requirement.

However, in N.America, they are unbelievably popular, but I think that is because a concrete bed and haunched edging woulkd give problems in areas of frost heave, and so they rely on these types of 'solutions' that can move with the ground as it rises and falls, without cracking the haunching and requiring annual repairs.

If you contact Marshalls (distributors of Keyform which they bring in from overseas) or Hauraton, they will be able to tell you who, in your area, stocks their kit.

2 - You can walk on the sand when it's first compacted, but, once it's screeded off to level and ready for laying the blocks, you should NOT walk on it at all.

If you leave these lumps in place, their profile can be reflected through to the surface of the eventual paving, and so, in a couple of years, you might find that some individual pavers were more prominent than their neighbours, or were proud and rocking because they were placed directly over these 'lumps' which have provided more resistance to consolidation than other parts of the paving.

As I say over and over again: the sub-base is the strength and integrity of a block paved driveway and skimping on it is a false economy.

Once screeded, you'll need to smooth out the highspots that will be formed where you placed the trammel bars. This is covered in the Section on the Screeding page that deals with "Cambers and Dishes". The final screeded bed should be fairly accurate and very 'sweet' with no obvious bumps or dips at all. Take your time with it - keep going over it, "tittivating", as we say, until you're 100% happy with the profile. Then, and only then, should you start to lay the blocks of the pavement body.

Assuming you've thoroughly compacted the sub-base and the bedding is evenly compacted to a regular thickness, the final profile of that bed will, to within a few millimetres at most, replicate the finished profile of the pavement. It's much easier to adjust the sand bedding than to lift blocks, re-screed and then re-lay, so time spent ensuring the bed is spot-on is time well spent. It's much better to spend an extra half-hour checking the bed than to rush in with the blocks only to find you've a ridge running right down the centre!

Flexibly-laid block paving is a very forgiving medium in which to work, so, even if you do make a boob, it's not all that difficult to lift and re-lay - far easier than it would be with a non-elemental paving such as concrete or bitmac, so don't fret too much. Take your time, and ask for help if you get stuck!  

You cannot re-sharpen a spent blade by forcing it through bitmac or sandstone. If you could, every contractor in the trade would be at it!

The Resiblock products are very, very good: in fact, they are probably too good for domestic paving, if such a thing is possible. They are one of the few companies that back up their claims with independent, scientific data, rather than anecdotal opinion. Consequently, there's no worries with the Resiblock stuff, as they have built their worldwide reputation by concentrating on specialist sealants for paving, whereas many other products are knocked out as cheaply as possible by companies with no technical data to back up their claims and no on-going research committed to developing even better products.

50 litres of sealant, whether it's Resiblock or any other, can be applied in less than half a day, including time to prep the area and standing guard to keep the cat off it while it cures. I wouldn't hesitate to use the Resiblock and half a day of my own time, rather than splash out 300 quid on some unknown mystery product. However, if your man is willing to tell you just what it is he plans to use, I'd re-assess the situation.

Anyway, their SupaSeal sealant is an acrylic, which is why it is cheaper than Resiblock. I've still not seen any tech literature, other than the standard promotional stuff, and they don't have a website......yet!

If you give them a call and tell them you were speaking with me, they'll send you all the info they have and I'll have another go at getting technical info from them as soon as I get the time.

I hear what you say about relying on consolidation to level out the difference, but it does work for me. Even using the pre-compacted screed method of laying, we expect 5-9mm of consolidation, but that's because we prepare the screed in such a manner that there is such a relatively high degree of 'give'. The grit sand we prefer to use as a bedding material allows us to do this, but I also know from experience that when a grit or a granite dust is used as the bedding material, there is considerably less 'give', perhaps 3-5mm, and so variation in block thickness becomes more of an issue.

Obviously, returning the blocks to the manufacturer is not realistic at this stage, but, if I came across such blocks at some future date, I'd certainly call out the Area Rep and listen to their attempt to lie their way out of trouble, because, if the manufacturers don't get this critical feedback, they will continue producing sub-standard blocks.

From a laying point of view, if you are forced to work with such irregular blocks again, maybe switching to a partial pre-compaction screed would give better results?

In the UK, the bedding sand required for block paving is a Class C or M sand, and then there are 4 sub-zones of those classes, stipulating allowable clay content and further defining the grading envelope. All of this is explained on the Aggregates. There is a wide range of sands available to us in the UK, ranging from genuine marine or fluvial sands, to quarry waste by-products. Contractors tend to have their own particular favourite sand that they find gives them the best results for their regular products. This comes about because they 'learn' from experience just what degree of compaction they can expect from a standard screeded layer rather than any real difference in performance of the sand.

As I mentioned, I'm not very familiar with US standards, but have you tried ICPI? They give out great advice to US-based block paving contractors and could probably tell you what they would recommend for dealing with blocks having such a wide difference in thickness. They also sell a number of guidebooks and leaflets for a few dollars each, and they make good reading. They don't have an online advice service, like this one, but they do have a freephone number, as far as I recall.

If the blocks are compacted 'dry', some joints tighten up and some widen, whereas, if sand is scattered over the surface, it seems to even out joint width, minimise skewing of individual blocks, keep cut blocks in place and, most importantly, ensures the sand is properly rattled into the joints so that those nasty empty joints that appear after a couple of weeks or so after completion are fewer, meaning less maintenance at the 6-week check-up.

I'm not sure why you've laid the edge blocks like that - I'd have laid them on a full concrete bed and hammered them down to level there and then, so that the body blocks can be laid on a full sand bed. As I've never experienced blocks laid in that manner, I can't be sure how they'll respond to final compaction, but my guess is that they'll 'dip' at the sand end while staying more-or-less put at the mortar end.

I'd be interested to hear what happens!

I've noticed that this phenomenon is more prevalent with multi-coloured blocks, that is, blocks containing two or more differently coloured concretes. I did wonder whether the hydraulic press that is used to compact the different concretes into the mould during manufacturing was set to a lower level of compaction or perhaps not vibrated, but none of the UK manufacturers are all that keen on revealing their exact manufacturing process, so my suspicion remains. Most of the block manufacturing plants I've toured, both in the UK and in Europe, all have vibrating presses, but the degree of vibration and compaction is not revealed.

However, the point is that these 'holes' are commonplace with that type of concrete block paver and the manufacturer will probably not entertain any claim for sub-standard materials. Still, your contractor really should be prepared to ask the manufacturer to send out a Rep so that your questions can be answered. It's not as though it costs the contractor anything, and it would come across as good PR. If there were a substantial number of the holey blocks on your pavement, 30% or more at a guess, then the manufacturer might be sympathetic, but would be quite right in pointing out that the contractor shouldn't have laid the blocks if there were so many sub-standard units.

If you want to use sealant, wait until you know whether you are going to get a vist from a Rep. If you seal the blocks before they've been inspected, you could invalidate any claim.

Applying a sealant will not eliminate these holes: they'll still be there after the sealant is applied, but the sealant will help to keep the pavement cleaner.

I would go back to the contractor, ask them to arrange for a Rep to visit the site and take a look at the blocks, and then take it from there, but I don't want to build up your expectations. I really don't think you're going to get the blocks replaced, unless, as I say, there are hell of a lot of them on the pavement, and the Rep is in a particularly generous mood.

As the blocks are now 12 months old, I don't think they'll get much worse. Obviously, some blocks will continue to develop more 'holes', but I would imagine that the vast majority of the holey blocks have made their presence known by now. Still, I'd definitely get the Rep down, though - 9000m² is not your average domestic driveway!

Even with the 'holes', your block paving should give you at least 20 years of service, possibly even longer. Some of the earliest block paving we did is now 22 years old and is still serviceable as a pavement, even if it is a bit grotty and could do with a damned good cleaning. I'm not sure that applying a sealant would dramatically extend the lifespan of your paving, although there is some research from studies on heavy duty block pavements (such as airports and freight yards) which shows that using a quality sealant does indeed reduce maintenance requirements and, so, extends the working life of such pavements.

Replacing the lot is no guarantee that the new batch of blocks will all be what we call 'tight', ie, no holey bits on the surface, and sealing any concrete block pavement immediately after laying is never a good idea. The blocks need time to 'settle in', for the jointing sand to be topped up (usually 4-8 weeks after laying) for any efflorescence to work its way out, for any settlement problems to come to light - I always recommend leaving a new driveway/patio at least 3 months before applying a sealant, but I know some folk are quite happy to seal them immediately.

You can work in the rain, if you're mad keen. It will do you more harm than it will the blocks, but, as long as it's not absolutely chucking down, both you and the paving should pull through.  

A rubber sole on the base of the plate compactor is handy, but not absolutely essential. You can use an old blanket or even a donkey jacket wrapped around the plate, if you find that the vibration is spalling the pavers. However, with a generous sand cushion on top of the blocks (6mm or so) the incidence of spalling is much reduced.

60mm fall over 2.4metres is more than ample, you'll be gflad to hear, and you can pave right up to the house brickwork.

You will probably get away with around 50mm fall, but don't go any less. It may sound a lot, but when it is laid it is hardly noticeable. What would you rather have - No standing water or a perfectly level table ?

Nigel

Find your finished level height on your house wall - 150mm below dpc level, mark it with a pencil. Use a straight edge (a piece of timber around 75-100mm by 25-50mm), 2.4m long and level it off your mark on the wall to the end of your patio. Get a wooden peg and hit it into the ground so the top of the peg is 50mm below the bottom of the straight edge when level. These 2 points - the mark on your wall and the peg height are your finished height levels.

Dig out your ground to approx 200mm below your finished heights, thus creating a fall in your ground. Then fill in with an even layer of sub-base 100mm. Keep measuring down from your straight edge. Compact your sub base.

Level out your scredding layer evenly and then lay your blocks as per the recommended way - look in the main pages for Tony's do's and don'ts.

If you do it this way, all your levels are even.

Good luck

If anyone else can explain better than me, have a go.!!

Nigel

Do not put any plastic under the sub base. If you are gonna use anything make sure it's a Geo-textile type membrane.

The sub-base will be ok for weeks/ months after it has been compacted.

Do not put in the sand layer until you are ready to lay the blocks. Make sure you use a grit type of sand - NOT building sand or the like.

Nigel