How to lay paving on top of concrete slab?

[rachelh28]

We are planning to lay crazy paving on top of our existing concrete slab. I've read about a couple of different methods including using sand as a base or using mortar. We also want to raise the height up by almost 10cm.Taking into consideration the paver thickness, can we layer mortar directly onto the concrete slab to our desired height or should we be doing something different to increase the height and then adding a 10-15mm later of mortar before the pavers? Any suggestions or tips much appreciated. 

[Jewelleryrescue]

Hi @rachelh28 

Great project you are doing/ 

Guide  :

- Cement mortar ideally need s to be 20mm thick at its shallowest so it has some strength. So your thickness of 10cm  minus  paver thickness (50mm?)  will give you a strong 50mm or so  mortor thickness this is great.

- Yes  you  most definatly can lay mortar on top of a  clean concrete slab in fact thats great as you will have a  flat surface to work on. 

- Garden pathes never have to be dead flat or dead straight in fact I deliberaly curve all mine if possible and put a slight tilt to run rain water off them.

Hi  @rachelh28 

 Wet  cement  OR  you  can do this  with no water it is much easier.  Still using dry (Sand and cement ) pre mix later you will water the path starting the cement setting.

Path thickness = 100mm (you wanted) -  Paver thickness eg 50mm  equals cement thickness of 50mm.  Note  when you lay cement add 5mm so 50 mm is now 55 mm this is to allow the crazy path to be tapped down into the cement making good contact.

Your  path make wet mortar  (premixed sand and water at bunnings) mix it with water pour it on the start point of your path so its ( tooth paste like  smoothness)  .  Start pouring it out  wet mortar or add  dry mix on old path and spreading it out to 55mm thick(  come down the path 1 meter at @55mm thick and flat Now  gently lay the crazy  pave on top of wet  or dry  cement.  Move it into position and tap  with  hammer a 1 meter long wood  (35x 75mm approx timber)across the  top of the crazy pave so it gently pounds the crazy paver down to 50mm and level as you want.

Tip the leveling timber is  like icing a cake if you see any lumpy bits put on the timber and tap it level with all the other stones.  If you have a low bit lift the crazy pave up and put more  morter under or dry sand  and cement. Now its level/  Slide the timber  down over the newly laid  crazy  pave and tap it down to you desired  path height.

Tip itsa good idea to have  path thick ness markers along the sides of the path so you know if your  work is too high or low, so you can adjust.

Puttin pavers on  dry sand and cement mix is the easiest way as  no hard  work to mix it up in a wheel barrow etc. plus you can take your time to add or subtract mixture to  get the perfect path/   .  Once the  path is laid you can  even add sand and cement powder between the pavers and then  with a hose saturate the path full with plenty of  water with a slow flowing hose (so mixture not hosed out  at all) Start the hose flowing at hill end of  path  it will flow  down hill and into the sand cement mixture.  This  will clean  paving surface at the same time. Move the  hose at need we  dont want so  much  water  mixture starts flowing out like muddy water.

Have you hear of cuflue the thin 5mm plastic board signs are made of . I would by a   bunnings  5 mm sheet (roll it up for car) and cut it into path edging strips eg 100mm each side your desired path thickness  use some pegs to hold it in place  now you have a  path with  channels on the outside and it will be the same level of  the top of your path as a guide and no sand and cement will spill or push out from under the  path while setting.

Well I wrote  a book  hope  this helps.

[EricL]

Hello @rachelh28 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about crazy paving.

It's great that you've received excellent advice from @Jewelleryrescue. 

I just wanted to be sure that you need to increase your concrete base to 10cm taking into account the thickness of your pavers. Before I make any suggestions, can you please tell us how thick are the pavers you'll be using? Can you also please tell us how big is the area you'll be tiling? If the area you'll be doing is quite large, I would suggest adding the concrete first to increase your concrete base height. You can then make sure that the added concrete will be flat and level.

Once the added concrete cures, it will now be much simpler to layout the pavers and you are not rushed to complete the task. If the pavers you'll be using are all at the same height, then you'll have a nice level finish. Once you have the pavers in the configuration you like, you can then apply the adhesive and stick the pavers to the concrete base. Once the adhesive cures, the last step will be to grout the pavers.

I suggest having a look at this featured discussion - Crazy paving front porch by @EleventhCoastal.

Let me call on our experienced members @Nailbag and @Dave-1 for their recommendations.

If you need further assistance, please let us know.

Eric

[Dave-1]

Good morning @rachelh28 

I would be using mortar to secure and to raise the 15ish mm in height that you want. Going through the response I am thinking aphoto of the area would be good to see as if its a large area then the way to do may change as @EricL has suggested. I have really come to like the crazy pave style ashave seen some nice projects in here. Please take a bunch of photos, well lots as you go and consider putting it up here as a project  

What sort of stone are you thinking of using btw? Just as a matter of interest more then anything.

Dave

[Nailbag]

Hio @rachelh28 

I have done this project a few times now and I would be essentially following the method of wet or dry sand & cement base @Jewelleryrescue has explained. In the projects I have done, it's always been a wet mix working on a small area at a time. I set my level heights on either side and then use either a string line or straight edge which I usual use a 1200 - 2400 spirit level (usual method) to check and maintain the height.

Nailbag