Q1 - The gravel filled gap between hard paving and the brickwork of a house is known as a 'Splash Strip' and is a bit of a nonsense, really. If the paving is laid properly in the first place, the splash strip is redundant, but that doesn't seem to stop some architects and designers from using them on every project. Anyway, as they are a bit of nonsense, there are no regulations governing them, they do not appear in the Building Regs and they are left to the whim of the contractor and/or designer. A typical splash strip will be somewhere between 150mm and 300mm in width, and is filled with a gravel chosen for its looks or its cost rather than any particular hydraulic properties.

Q2 - work to the lower of the two DPCs. It's better to be more than 150mm below dpc than slightly less than 150mm.

Q2b or is it Q3? - Nope. All the info you need is here.  

The joints between the individual flags act as a sort of 'control joint', and so allow the rigid bedding to crack in a pre-determined spot, which is all well and good, but then why not just rely on a flexible bed that can accommodate slight settlement of the sub-base? In my experience, when rigidly-bedded flags start to rock, they continue to rock indefinitely, and the only remedy is a lift and relay. With flexible bedding, the flags have a chance of re-establishing a non-rocking equilibrium, noot that it always works that way!

On public streetworks, the 'mortar bedding' is often a lime-based mortar that remains slightly more flexible than a cement-based mortar. This is reckoned to accommodate slight movement more successfully than rigid bedding and it does seem to work. However, getting a lime-based bedding mortar for a patio is not really feasible, as the manufacturers like to deliver in cubic metres, not in barrowfuls!

If you use a weak mortar (or the 10:1 bedding mix that I advocate), then you should be ok for a patio. For the driveway, I'd elect to re-use the existing sub-base if at all possible and then choose the bedding according to the type of flags being laid. If they were BS pressed concrete flags or 50mm+ stone, then a sand bed or a weak bedding mix would be my choice, but for cast flags (patio stuff) or the Indian sandstone wafers that are very popular just now, then you really, really, really need a full concrete bed, 50-75mm thick, to give then the necessary strength.

If you must use a cement mortar bed, then use a full bed, not spot bedding, especially for the driveway work. Spot bedding causes more bloody problems in the long term than any other method of bedding!

An edging for your patio is not essential - it's a decorative touch that might look nice, but it does nowt for the actual structure.  

D'yer mean summat like....

...if so, then there is no minimum radius, theoretically. However, a radius of less than 600mm is very, very tight and awkward to cut.

2 - If I knew what you were doing, I might be able to tell you how to do it, but, as I'm not sure, I'll wait for clarification first.

You could use a Nangle Grinder from Argos (or anywhere else, for that matter!), but you will find it difficult because of the small blade size, which means you'll not always be able to achieve full-depth cuts, and the blades don't last very long when cutting concrete or stone. On t'other hand, the small size of the Nangle Grinder makes it easier to handle, especially for intricate cuts or tight radii. All-in-all, it's probably worth investing in a Nangle Grinder, as you can use it for other DIY jobs around the home, whereas a Power Saw is far more expensive and less useful for the average DIYer, even if it does better cuts.

However, you MUST get a pair of goggles, a decent dust mask and a pair of gloves. The dust that is spit out from the cutting is nasty, nasty stuff, and, because of the small size of the Grinder, you tend to be working even closer to the cutting edge than you would be with a Power Saw.

3 - Heritage Paving - that price is about right. There are umpteen different wet-cast riven reproduction flags on the market, and it's a matter of finding one you like. To be honest, you don't get anything decent for much less than 20 quid per square metre, and, for the top-of-the-range concrete copies, you're looking at 30-50 quid per square metre. Meanwhile, you can get genuine stone flags for around 20-25 quid per square metre - admittedly, they're very thin imported Indian sandstone, but, for a patio, it's hard to beat them for aesthetics at that price.

Stonemarket York Riven - have you seen it 'in the flesh'? The surface is quite heavily textured, which is not to everyone's taste, as it can be impossible to get the patio table to stop rocking, but from a quality point of view, it's a good product. There's not a lot of variation in the colour, but there's a good range of sizes and, with a contrasting mortar joint, it can look quite effective.

To cut a 600mm long flag, in a simple straight line would take around a minute, I suppose. A bit quicker with a diamond-bladed power saw; a bit slower with your Argos Nangle Grinder. It depends on how deep you cut. You don't need to do a full depth cut - a 10-15mm cut on the face and a 10mm deep cut on the back will usually be enough for the flag to 'snap' and save time, effort and blade.

For a curved cut, you may well be forced into doing a full depth cut, so a 600mm long cut might take 3 or 4 minutes.

Remember that a sub-base needs to be at least 75mm thick to have any inherent strength. Owt less than that is just a fill layer, which isn't a problem, but shouldn't be thought of as being load-spreading.

And the actual material used to form the sub-base is critical. Relying on brickbats and bits or rough 'hardcore' can cause more problems than it solves. It really is worth splashing out on a tonne or so of granular sub-base material, such as DTp1 and using that to form the sub-base, as that will make a dramatic improvement to the sub-grade, with or without a geo-membrane.

Have a read of the Geo-Fabrics page.

If you use a mortar bed, then you need a base of some form - a sub-base is ok for a patio, but it needs to be properly prepared and thoroughly compacted. A base would be better, given the problem with the thickness of the slate, and for that, I suppose the best material to use would be a concrete, something around 20 Newtons strength (whatever that is in the strange, nay incomprehensible, 'bags' that seem to be used to define concrete strength in the US).

If the ground is reasonably stable, then you could lay the slate directly onto a concrete bed-cum-base and miss out the mortar bedding, but the skill level required for this is quite high and you need to work at a good pace to cover the concrete before it starts to set.

Given the rain you have to contend with, I'd suggest a minimal sub-base, just enough to prepare the ground, then a base of 100-150mm of concrete, and finally, the slate laid on a 20-35mm thick layer of Class II mortar.

How does that sound?

If the slate is machined tiles with a ridged base, that really does suggest that they were intended for flooring, and therefore would be laid on a mortar screed over a concrete base, as discussed earlier.

The 'voids' sound worrying - that's something normally seen with the hated spot-bedding,. Does that sound right?

Anyway, to rectify the path - I can't say what would be best unless I could see the paving for myself. You could make a temporary repair to the lost or sunken paving by overlaying with a fine-grained concrete, but I'm not sure how feasible that would be.

If you were looking for a cheap, temporary surfacing as a replacement, then gravel of some form would be the answer, but it doesn't respond well to regular inundation. Still, when you come to do the permanent job, the gravel can be reclaimed and used a coarse aggregate for concrete.

Next cheapest solution would be to use the nasty little 99p flags from the DIY sheds and bed them onto a semi-dry mix, but, if you're going to that sort of time and expense, it's debatable whether you're not better off doing the 'permanent' fix now, and saving all that effort.

Even if the grout does take a while to cure, that really shouldn't affect cleaning, as the microscopically thin smear of grout on the surface of the slate will not be affected by joint width or depth. However, you have to offset that against the obvious reluctance of your builder who seems to want to find problems with this method.

As for the grout cracking - I'm not having that! Most of the waterproof grouts have a damned good flexural strength and are far less likely to crack than mortar.

Using a mortar is ok, and there are additives that can be used to make a standard cement mortar as waterproof as any tile grout, which may be a better solution than using a sealant, which has to be re-done every couple of years or so, anyway!

If your builder is dead set against using the grout, then maybe you could consider summat like Ultraflow, a rapid setting, hard-as-bloody-iron pumpable mortar from Instarmac. That'd do the job, and, because it can be applied via mastic gun, there's little or no spillage and no snots to clean!

Q2 - Because they're eejits, possibly. This is the notorious 'Splash Strip' that is supposed to reduce the risk of damp but is a bit of a con, as it just reduces the amount of expensive paving that has to be laid. There is no Building Reg. that insists on a Splash Strip and I have never, ever heard a single convincing argument for its use on a residential patio.

Q3 - 50-60mm of sand is too much. 50mm maximum, otherwise it can lead to problems with settlement.

The cement binds the sand grains and makes them resistant to groundwater movement and ants. If you have a really good coarse sand, such as the stuff we get from the Pennine quarries around Horwich, that can generate sufficient interlock to more or less bind itself, but many of the river and marine grit sands need a peppering with cement to encourage them to stay put.

Q4 - using a dry sand/cement mix for the jointing on a flagged patio with 8-12mmm joints is a waste of time and materials. It won't last more than a couple of years, if that! If you must use dry mix, then it must be swept into a joint that's been freshly buttered with mortar, so that it can properly bond to the mortar and to the flag. Best of all is a proper mortared joint.

Q5 - it would be, as soon as I've found a way of getting 30 hours into the day! Ackshirley, this is another of those pages in my 'development' folder, along with a similar page for Block Pavers and Clay Pavers, but the choice is so-o-o-o HUGE that the Block Paving version, which goes under the codename "Wotblok", has been in development for the last 2 years!

There's a list of fairly local suppliers of stone paving on the Stone Links page. Stone Essentials in Rossendale is the nearest I can think of to you - tel: 01706 211120 and tell them I referred you.  

If you ever get down as far south as Stockport, Ernest Axons at Cheadle Heath has a good selection of paving materials, too - 0161 428 0314.

However, for a patio, we needn't get too concerned, as we're not anticipating massive loads. If the ground is firm and stable when dry, then it's probably ok - if, when you jump on it, it wobbles around a metre or so away from where you are, then that's more of a problem.

If you have any concerns, then using a geo-membrane would help, but, for 95% of all patios, laying the flags on a cement-bound bed, such as the 10:1 mix of grit sand and cement that I advocate, is more than adequate.

Lay your paving on a bed not exceeding 50mm. I like to add a sprinkling of cement to sand bedding beneath patio flags, as it helps stabilise everything.

And you're right, if there is any movement in the flags once they're laid, then the jointing will crack. This shouldn't be too much of a problem as flags are supposed to be firm and stable on the bed and not rely on the jointing for their strength, unlike, say, blocks or setts.

However, in practice, especially with smaller patio flags, the jointing can contribute hell of a lot to the stability of the flags, and so, if there is any movement, a rigid jointing medium, such as mortar, will crack. But if you use a flexible medium, you either pay a small fortune for a sealant such as Nitoflor, or you use an unbound medium, such as sand or splitt, which allow vegetation to establish itself on the pavement.

You have to decide which is best for you. With stone or riven-effect flags, I prefer mortar jointing, but with some of the polished or shot-blasted flags, a 3mm flexible sand-filled joint is fine.

If it's an impermeable membrane, such as a dpm, then it could cause problems.

A non-woven permeable membrane looks like the stuff on the Geo-sheets page, a random orientation of fibres that are thermally bonded (techno-speak for hot glued).

50mm is the maximum thickness for a bedding layer, and 30mm is the minimum, although you can go down to 12mm if it's a mortar. Like a lot of other things in life, you don't want too much or too little. 40mm is ideal.

Working in the rain is not a problem, unless there's mortar involved, but if it's chucking it down, then it's best left. Fine drizzle is not too bad, and showers are tolerable, but steady, non-stop, soak-you-to-the-bones rain, such as we have today, is awful and you're better off seeking shelter in the a local alehouse while revising your strategy!  

Obviously, a 6mm gravel wouldn't be too bad, as it will mix in with the coarser particles of the sand, but a 20mm gravel would  cause much more of a problem and is best left as a coarse aggregate for knocking-up concrete.

If you're using the 10:1 bedding mix, don't make up more than you will cover with the paving in around 3 hours, as the cement starts to go off as soon as it comes into contact with any moisture.

Their yard is at the back of the Cemetery in Ince, on the Warrington side of Wigan and worth a visit if you're really keen on the Indian stone.

There's also Hardscape in Bolton, but I'm not sure how keen they are on "diy'ers" visiting their yard. Still, you can call Matthew Haslam on 01204 590666

Let me know how you get on, as I'd be keen to hear your thoughts on what these suppliers have to offer, and how helpful they are when it's a non-trade enquiry.

The Raj Green usually works out quite well, but I'd be wary about separating the rougher flags from the smoother ones - you could end up with a patio that looks as though it's been constructed in two stages from different materials. It's best to mix the textures and allow the paving to have a more random look.

Anyway, for what it's worth, I'd offer the following advice...

Bedding - the existing concrete base sounds fine, so there should be no problem re-using it, provided that the extra height created when you lay the new paving will not compromise floor levels or any damp proof measures you may have. I can't see any point in breaking out the existing base and replacing it with a flexible sub-base - it's a poorer construction, it involves a lot of extra work and it's unnecessary, as far as I can see.

For the actual bedding, the tile adhesive sounds ok. In UK parlance, anything less than 30mm thickness is classed as a tile rather than a flagstone, but that, in itself, is not sufficient reason to use a tile adhesive for a job such as this. The thin nature of your chosen stone means that it must be laid on a full bed. I'd be worried about using my usual 10:1 bedding mix, as it's not intended to be subjected to repeated freeze-thaw cycles. A mortar would be ok, I suppose, and would be my choice if there were any deviation in thickness of 5mm or more, or an uneveness in the base, but, as all that seems to be fairly regular, then a proprietary adhesive would be a better choice, as long as it is approved for external use in the climatic conditions you have to endure.

But is this bedding material suitable for use as a jointing material?

Movement joints - you cannot bridge the expansion/movement joints with your stone paving. If you do, it will probably crack. Ideally, the joint is carried through to the surface of the paving, so you'd have to align your random-shaped stone in such a way that the underlying joint could be extended upwards, preferably with a flexible jointing compound (I can't suggest one as I don't know the US-ian market, but in the UK, we'd probably use Thioflex or Nitoseal).

Although you might not notice it, there will be some movement of the slabs either side of the joint, and, if you use a rigid medium, such as stone, to bridge the joint, then the shear forces will be transferred from each slab into that fragile, 25mm thick sliver of stone, and, as stone is absolutely useless when in tension, it will simply crack. If you had used a mortar or a low-strength bedding medium, it might be that the 'crack' would develop along the interface between the flag and the bedding, but with a decent adhesive, such as we described above, then the stone itself is the "weakest link" and the crack will appear as a fracture in the stone.

However, there's no need for you to have a perfectly straight line 'joint' in the stone paving, you can create a gap over the line of the joint that varies in width from, say, 5mm to 40mm, and fill that with the flexible joint sealant.....

I hope that answers most of your immediate questions, but if you've any more, I'll try to help, and I'd definitely be interested to hear how you get on with it all.

However, you have your sequence of operations arse-about. You need to do the repointing first, then the cleaning and finally the sealing.

To do the re-pointing, mix your own mortar - a Class II mortar (4:1) with a bit of added colour if you like, and repair all the joints, not just some of them, or you'll end up with a patchy-looking effort.

I have a deep mistrust of the ready-made mortars sold in 25kg or 40kg bags at DIY stores. They're only sand, cement and plasticiser, measured and bagged, and then you're charged 4 times the going-rate. They are no better than self-prepared mortars.

Give the freshly pointed paving at least 3 days before washing down with the acid. And once you've got it all nice and clean, with properly filled joints, the choice of sealant depends on what finished effect you want. There's a long posting I made in this forum entitled Sealants for Slabs that lists the pros and cons of various products. You have to choose the one you think will give you the finish you want.

Cat litter is claimed to be good at drawing out oil from stone paving, but I can't say if it would work with slate - still, there's no harm in trying! Failing that, an oil remover, such as Jizer, might be what you need.

Candle wax will melt if you apply gentle heat, and can be absorbed into a paper towel, then treat the residue with a degreaser, as mentioned for the olive oil.

We get both crushed granite and crushed limestone in this part of the world, and there's nowt to choose between them. Granite is hard and inert while limestone has a tendency to self-bind, making it a popular choice for northern road builders. For a patio, it really doesn't make that much difference - it's the 'grading envelope' ie, the distribution of lumps and fines, that is more important than the type of rock. As long as there's a good distribution of the lumps and fines, then it should be "reet gradely" as they say in Lancastrian English.  

So - how much does a ton(ne) of crushed rock cost in Texas-shire? British buyers have to pay around 25 quid (40 dollars) for a single tonne.

$40 for a cubic yard is around $48 per cubic metre, or $20-24 per tonne, which is around 15-18 quid per tonne, a good bit cheaper than we can get it in the UK in small quantities.

For your second point, I like to butter the wall and then place the flag as that gives a more certain joint than laying the flag 'dry' and then trying to poke in the pointing mortar to fill the joint.

You don't mention what type of jointing you're using. If you're butt-jointing, then any deviation from true will be highlighted, but by using a 10-12mm mortar joint small deviations can be accommodated quite easily and the transition between flags 'smoothed', if you know what I mean.

However, now that the flags are in and on that bedding mix they'll be damned hard to extract, then you might be better off getting a diamond-bladed power saw to "grind" off any lips. It's not a pretty effect, but it's better than having one of the residents trip.

Just how much of a bow are we talking about over the length of the flag? 5mm? 10mm? More??

And, to answer your 2nd Q, taper edge down. so that the joint is narrower at the surface than at the base. See the Laying Riven Paving page.

The other benefit is that, when laid with a mortar joint, as they should be, the mortar is 'locked-in' by the shape of the undercut.

Basically, they should supply you with flags from the same batch, as that is what you ordered and you did make it quite clear to them. If a contractor had been treated in this way, they would take them back and ensure the order was filled as requested, and so, IMHO, they should do the same for you.

Contact Keyline first thing Monday and speak to the depot manager, not one of the underlings. Don't have a rant, but explain the situation calmly, and tell him that you've had to postpone a contractor as you couldn't risk having them lay the flags as supplied by Keyline, and that you've had to pay the contractor for a wasted Saturday - that should get you a bit of sympathy.

If you get no joy, then contact Keyline's Head Office and contact Marshall's themselves. Even though it is not their problem, directly, they can exert far more pressure on Keyline than you or I can, and they are usually quite keen to help out with this sort of 'customer relations' problem.  

Don't give up!

You could use a flexible sub-base (100mm DTp1) if you prefer, but the full concrete base is best for patio flags, which have very little flexural strength.

Leaving big wide gaps can, and probably will, cause problems with flags being 'flicked' upwards when trafficked, which is why I'm so keen to push you towards a full concrete bed, that will hold the flags firmly in place. The concrete would, ideally, come up the side of the flags, to within 25mm of the surface, and then fill the gap with your chosen gravel, pushing it into the still-plastic concrete before it sets completely.

A weak bedding mix (10:1) won't be strong enough to restrain the flags in this sort of design. It's fine for patios and flags laid with 'normal' joints, but for this type of project, it's best to think of it as a series of stepping stones, rather than as a composite pavement.