Paving with bricks over concrete slab

[Chumley]

Hi all,

I'm normally a woodworker - bit out of my depth with paving - but I have need (or at least swmbo does).

Outside my back door I have a concrete slab (about 5m x 2m) which I want to cover with bricks (old Canberra Reds) and I want to continue the brick paving out beside the existing slab in a kind of "P" shape. I can arrange to get the ground of the semi-circle (currently a grassy slope) to match the level of the concrete slab. I don't think I'll have any height problems as the bricks on the slab will still be a step down from the back door.

I planned to lay a bit of sand, maybe 25m, and just bed the bricks down on top of this - will this work? Do I need to use any particular kind of sand? Do I need something different where the bricks sit on dirt, roadbase perhaps? Do I need to put a run of mortar at the exposed side of the slab, like you see on brick paths, to hold the bricks in place? Do I need to worry about the different structures under the bricks (concrete and dirt)? Do I sound as though I don't know much about paving (you can ignore this one)?

I'd appreciate advice.
Thanks,
Chumley.

[Grunt]

You can certainly put your bricks down on a layer of sand on top of concrete. It will be very stable over the concrete.

Just use brickies sand.

For the other areas, you'll need to dig it out deep enough for 100mm of gravel, 50mm of sand and what ever your brick size is making sure that the bit over the concrete is at the same height of the bit that isn't.

I got a professional to do my old place in Brunswick in old reds. He left a gap between each of the bricks and filled it with mortar. Looked a treat.

I have done a bit of paving myself and also paid professionals to do.

The jobs done by professionals looked like they were done by professionals. Mine jobs were not quite so. No bad, just not in the same league as theirs. Mainly, they can do curves and make them look good. I stuck to straight lines.

Chris

[Dr Jan Itor]

I planned to lay a bit of sand, maybe 25m, and just bed the bricks down on top of this - will this work?

It will work alright, but you won't need to go as deep as that!

[Grunt]

Well you've got to allow for a bit of compaction.

[Harry II]

It will work alright, but you won't need to go as deep as that!

You definately need to hold the edge pavers in position with cement. If your going to "wack" the pavers in with a "Wacker", the pavers off the slab will be driven down (depending on the sand used and how compressed it is) 5mm to 10mm, I'd be careful of wacking the pavers on the slab if you go too skinny with the sand then the "old" bricks may crack, give them a good bed to sit on.

[Honorary Bloke]

I'd be careful of wacking the pavers on the slab if you go too skinny with the sand then the "old" bricks may crack, give them a good bed to sit on.

Yes, but 25 metres of sand does seem a bit excessive.

[Chumley]

Um, I think that should have been 25mm of sand (I knew what I meant and even read it back to make sure it was clear) -- 25m would be about 6 or 7 storeys, a bit hard to compact.

Thanks for all the advice, much appreciated.

Cheers,
Chumley

[joe greiner]

The part supported on concrete, and the part supported on dirt, will never behave identically no matter how much compaction you apply. Allow for relative movement with a sand-only joint or sealant - no mortar.

Joe

[Grunt]

My last place had some professionally laid pavers that were over concrete and dirt. After 4 years, you couldn't tell where the concrete ended.

[joe greiner]

Professional installation and sand cushion on the concrete probably helped most, but also, 4 weather cycles in Brunswick should be more benign than in Canberra. Believe me, at 35-40 degrees North latitude, you'd see it.

Joe

[Terrian]

You can certainly put your bricks down on a layer of sand on top of concrete. It will be very stable over the concrete.

Just use brickies sand.

errr, I wouldn't use brick sand, too much clay in it, better to use triple washed sand (sandpit sand) or concrete sand IMO.

[Terrian]

You definately need to hold the edge pavers in position with cement. If your going to "wack" the pavers in with a "Wacker", the pavers off the slab will be driven down (depending on the sand used and how compressed it is) 5mm to 10mm, I'd be careful of wacking the pavers on the slab if you go too skinny with the sand then the "old" bricks may crack, give them a good bed to sit on.

if you are going to use a wacker plate, put carpet on the plate, less damage likely to the bricks (or pavers)

[Terrian]

Um, I think that should have been 25mm of sand (I knew what I meant and even read it back to make sure it was clear) -- 25m would be about 6 or 7 storeys, a bit hard to compact.

nah, just put the sand in in 200mm layers and compact each layer )

[Planned LScape]

Yes as Terrian said dont use brickies sand or packing sand, it will swell when wet and shrink when dry, and also go rock hard sometimes causing breaks in pavers.

Use single washed/river sand/course sand for the bedding. easiest way to do it is grab some 25mm steel square tubing, or timber and lay that down to your levels (make sure you allow 5mm or so for compaction) and throw the sand over the top and screed over the tubing with a large steel straightedge. Compact a little as you go, then remove the tubing and fill channels with sand using a float.

Lay your bricks then throw triple washed/fine sand over the top, sweep in and compact with a protected whacker, then sweep more sand in. Haunch the sides with some concrete or edging to keep it all secure

[Chumley]

Hey all,
Thanks for all the advice - I solemly promise to take a photo and post it after doing the job - I'm off to Amber tiles this Sat with the boss, so should be starting soon.
Thanks again,
Chumley