The Brew Cabin

Dear Mr McCormaic
I'm about to embark on laying two adjacent 3.3m diameter circles formed from cubes (3 or 4 inch depending what I can get) with a border of large setts and a yorkstone circle at the center. I blame the great pictures on your site for inspiring this design element in the garden.

Your website contains great advice so I'm just taking it steady as its all new to me. The one worry I have is using a whacker on the stones once they are laid. My instincts tell me not to do it if the surface is already level and tapped down with a mallet. I worry about the stones falling about as they won't be supported by gravel or any pointing.

Advice offered at this stage would be much appreciated.

Best regards and thankyou for setting up this site. I stare at the photos daily!!!

There's no need to use a vib plate compactor at all, Damian, if you're using a rigid bedding method (ie, laying on a cement-bound bed). Assuming you are using a rigid bed, then once the setts/cubes are tapped down to level with the rubber mallet, that's it: end of compaction, no need to do any more. It's just a matter of jointing them (that's the real fun!!) and then sitting back in your favouritest garden chair, with a creamy pint of Dr Boddington's finest and enjoying the view! :)


However, if you're going for flexible bedding (ie, sand only - no cement) then you do need to compact with a vib plate, but then your edge courses need to be laid on and haunched with concrete, to stop everything else from moving when you run the plate over them.

Whichever method you choose, it sounds like a stunning design, and I'd really love to see pictures of the finished project, or even pictures of the work in progress!

Hi again Tony,

Finally got my 4 inches of hardcore whacked in with 2 inches of sand on top also whacked in. My circles have ended up having diameters of 3.1 and 3.3 metres.

I have a few questions which are bothering me now. How do you determine quantities for this job assuming I will be using 4 inch cubes (with a 1/2 inch joint)? Secondly, would you bed in the perimeter setts and work inwards or start at the centre and work outwards?
Finally, another "advisor" at work has said its essential to lay more loose sand beneath the new cubes as you lay them ..."to allow you to correct their levels". This sounds a bit thin on common sense to me since there is 2 inches of sand already beneath the stones???

I'm hoping to get the stones ordered this weekend so if you can get around to a reply before then I'd be delighted.

Thanks a million for the site again. The quantity calculators menat I didn't even have an extra bag of sand or hardcore left over after it was all whacked. 3 cheers.

All the best..
Damian

PS I didn't feel it would be useful to post piccies of 2 sand circles.....

Hi again Damian,

to determine quantities...

3.1m dia + 3.3m dia = 7.5m² + 8.6m² = 16.1m²

....and using 100mm setts with 12mm joints, there are approximately 81 setts per square metre, so, in theory, you'd need around 1,304 setts. To allow for wastage and cock-ups, I'd get 1350, if buying by quantity.

Next: methodology. I would start in the centre and work outwards. You need to prepare your screeded bed before laying the setts, and there needs to be a degree of fall from the centre to the outside edge, so bear that in mind. Position the centre stone, then the first ring, which will, as you can see in the drawing below, require some trimming to get a neat finish. Continue adding one ring at a time until you get the the final, outer ring, which really should be laid on concrete, tapped down to a level approxiumately 10mm lower than the rest of the setts, and then haunched with more concrete to hold everything together.



Give the concrete a day or a couple of days to 'set' and then you can consolidate the rest of the setts in the circle using a vibrating plate compactor (Wacker Plate) and joint as required.

There really is no need to add extra sand, If you have a sand bed, why would you add to it? Yes: there will be some variation in level between the setts - that always happend with the cropped setts, but the consolidation process evens out everything.

How are you going to joint the setts?

Thanks for the info Tony. I'm going to do pitch jointing.

Sounds good - you must take some photos and let me see the finished results. :)

Hi Tony,

I've ordered the stone today so fingers crossed that it arrives before Ryanair drops off the laying crew.

One thing bothers me though. You mention having a camber from the centre towards the edge of the circles.
Would this be in addition to a gradient from the front of the first circle to the back of the last circle or as an alternative? I've whacked in a 5 cm drop over 7 metres from front to back with this job?

Thanks again. The tension is palpable in the house as the big day arrives :)

It's not so much 'camber' on the circles - as long as there is fall, so that water will not hang. Some folk lay circles dead flat, with the result that they get a free water feature every time it rains.

The way to avoid that when laying to a flat site, is to lay the circles so that the centre is slightly higher than the outer edges, but, if you have a natural gradioent to the site, then there's no need to introduce extra fall/camber to the circles.

50mm over 7 metres is a bit tight for fall - 1:140 is around half of what I'd allow on a project such as this. Setts can be difficult to drain, because of the very uneven surface texture, so I like to work with 1:60 to 1:80 (crossfall or endfall). Aim for at least 100mm over your 7m run

Hi Tony,

I can't believe this weather we are having at present. My fabulous screed layer of grit sand has been amazingly consolidated with all the rain. Looking through your guidance on screeding I interpret my best option as being to rough up the sand again to the desired level and maybe toss a few new bags in to help it along. The stone arrived yesterday...........looks like its going to be a long weekend. The depth of the stones ranges from 2.5 to 4 inches. I'm going along with the idea of just shoving an extra bit of sand under the short ones at the moment.

The inner two courses in the diagram above look great. Is there a simple way to calculate the angle of the cuts?

Thanks again.

Damian

You're probably nearly finished with all this now, but I've been away on a mercy mission and wasn't able to post a reply any sooner.

Let us know how you got on - and the thing about the angles: it's 360 degrees divided by the number of units you plan to use in that particular ring. :)

Hi Tony,
Hope the mercy mission was succeessfully resolved for you. The circles were an intense topic for discussion around the coffee table and we came to the same conclusion as yourself. Execution was not such a simple manner. In an ideal world, I would have knocked up a plywood form and used it as guide for a big stihl saw. No such look. (A bad workman blames his tools but mine have been damned for all eternity!!!).I hired a block chopper for a day and it worked about 10% of the time in giving a good cut. Most of the time though, the bottom strata of the cube would give way before the surface making the cutter redundant. Moved onto small angle grinder with a 4.5inch diamond blade and nicked the 4 sides of the stone to be cut before delivering an almighty wallop with the "persuader". Did the trick. Anyway, one circle is laid now and it looks even better than I had hoped. I think the pitch jointing is going to make it. I'm praying for a week of dry nights so I can make good headway with the second circle before the weekend.

ATB Damian

Send me some pictures, if you get the chance. :)

Ho Tony

Well, a few hours on the cube laying each night is paying dividends and I'm over half-way through the second circle now.

Is there a rule of thumb for the distance you should allow for lateral travel of the main bed of cubes after a few passes with the whacker plate. I'm trying to gauge how far from the edge of the main body of the patio to lay the edging course of cubes in mortar.

The compliments keep flying at home for the job so far but as usual it'll be the plants that get all the glory at the end of the day :biggrin:

ATB

Damian

Hi Tony,

Well, I've finished filling in the bitumen in 1 of the circles and it looks a treat. I've found that the big spills onto the cubes are effortless to take off as are small blobs (less than 1 cm in size). However, in 1 or two places I have a thin film of pitch which is very tough to take off. Is the best strategy to remelt it by deliberately pouring a good dollop of freshly melted pitch over the affected area and after it solidifies the two should have combined???

All advice appreciated.

Damian

Those thin films of splashed pitch are, as you say, a bit of a swine to remove. A craft knife is the best way, along with the realisation that you are never going to get it 100%. If you look closely at any other pitch-sealed sett pavement, you'll see the very same thing, and it's an unavoidable fact of life when it comes to pitch sealing, I'm afraid. Remember, it's the overall finished effect rather than the minutiae that make the finished pavement look good, so, get the rest of the paving sealed, then just pick off any of the really noticeable splashes with a craft knife. The dead thin filmy splashes tend to wear away in 12 months or so.

Adding more pitch to them may not work as you imagine, but it has worked for me in the past. It seems to be more effective on hard granite/basalt setts, rather than on sandstone, though. If you want to try it out before smothering the lot in molten pitch, choose a discreet corner and see how that fares.