The Brew Cabin

I am about to begin building a block paver patio which will butt up against an existing concrete walkway along two edges. Having read and re-read your info about edge courses, i just want to be certain I am doing it correctly. Will a 50 mm bed of concrete be sufficient for the dge course next to the existing walkway? If not, what is the proper depth/method?

Thanks very much for the wealth of helpful information you provide on your site. I'm sure I'll still make plenty of mistakes, but it won't be for lack of quality information!

-Stephen

Where the edge courses run alongside the existing concrete "walkway", there is no over-riding need for them to be laid on concrete at all - think of the walkways as the walls of a house or similar. There's no way the edge blocks can moved laterally, because the walkway is holding them in place, and, if you get the build-up right, there's no way they can move downwards.

However, having said all that, I'd still prefer to lay the edge course blocks on a minimal concrete bed (50mm is plenty) for a couple of reasons. Firstly, I'd rather lay the edge course blocks to an accurate line and level, rather than rely on using the concrete path to guide me. If you use the concrete paths as screed guides, you will be replicating any level error in the paths, both in level and in line. And secondly, laying the edge courses on a bed of concrete holds them more firmly in place when it comes to screeding the body of the paving, than relying on screeding from blocks laid on sand.

Has that cleared things up or just confused you even more?

Thanks for your reply.

The reasons you state make sense, so I will plan to use concrete for the edge course, anyway.

I do have another question concerning slope. My patio is going to be L-shaped. Both legs of the L are 13.75m long. One leg of the L is 1m wide, the other 4.25m wide. Both legs of the "L" will slope away from the existing concrete walkway (I was planning on the 1:80 ratio for slope). I think I understand how to lay out the level lines, but my question is in which layer below the pavers do I account for the slope? My instinct would be to do it in the excavation phase (meaning that when I dig down, I account for the slope while digging). If the slope is not accounted for during excavation, then how can the slope be acheived without the depth of the sub-base being uneven? Am I making any sense? Or am I totally confused?

Thanks very much for your help!

-Stephen

No, you're making perfect sense and you've got it dead right - you form the gradients in the excavation. This ensures that you have a sub-base of regular thickness, and more importantly, you have a bedding layer of a regular thickness.

I look forward to hearing how you get on. :)

Ok, new question concerning excavation. I have spent the last two days excavating the site and I have (with the help of a sod cutter) managed to dig down to a depth of 100 mm. However, it is becoming increasingly difficult to dig deeper. With time and considerable effort I may be able to wrestle out the remaining 100mm, but I was hoping you might have some suggestions that might make my life (and the toll on my back!) a little easier?

Thanks again for all your help!

-Stephen

There are no vehicles going to use this pavement, are there, Stephen?Assuming there aren't then you can 'skimp' slightly on the sub-base requirement if the ground is as hard as you say.

Use a pick-axe or mattock to get the dig down to 170-180mm below finished paving level, then just use a 70-80mm layer of sub-base, but get it well-consolidated.

If you're using 50mm blocks, you could also get away with just a 40mm bedding layer, saving another 20mm of digging.