How to lay crazy paving? Mortar mix, technique and tools?

joshs

Hi there,

Doing a landscaping project and am up to laying the travertine crazy pave stone. I've left 40mm between slab and finish level for 20mm mortar and 20mm stone.

My mortar mix is 20kg bag cement, 4-1 sand, 1L bondcrete and some plasticiser.

Do I need to use a 20mm notched trowel for this or just a flat trowel? Do I need to butter the back of the stone? I'm going to do 1sqm at a time, do I need to put mortar everywhere on the slab? or just spot mortar where the stone is going? I'll be using a wide joint mortar from Dunlop at the end.

Here's some photos from my backyard so far

EricL

Hello @joshs

Thank you for sharing your question about laying your travertine crazy paving. It sounds like you've put plenty of planning into the preparation, and your finished levels should give you enough room to achieve a solid bed. For crazy paving, a flat trowel is generally the better choice rather than a 20mm notched trowel. Notched trowels are more commonly used for laying regular tiles with adhesive, whereas crazy paving on a mortar bed benefits from being individually adjusted to suit the varying shapes and thicknesses of the stone.

It's also a good idea to butter the back of each piece of travertine with a thin layer of mortar before placing it onto the mortar bed. This helps improve the bond and reduces the chance of voids beneath the stone. Rather than using spot mortar, aim to provide continuous support beneath each piece by spreading mortar over the area where the stone will sit and pressing it firmly into place. Full mortar coverage helps prevent hollow spots, reduces the risk of movement or cracking under load, and provides a much stronger finished surface. Working in sections of around 1sqm at a time is a sensible approach, as it allows you to maintain a workable mortar bed without it drying out before the stones are positioned.

Before laying the stone, it's also worth ensuring the concrete slab is clean and slightly damp, rather than completely dry, so it doesn't draw moisture too quickly from the mortar. Once the paving has had sufficient time to cure, you can then complete the joints with your Dunlop wide joint mortar, following the product's recommended curing times. Taking your time to dry-lay a few stones first and adjust the joint spacing as you go will also help achieve a more natural looking finish.

If you need further assistance, please let us know.

Eric