How to Lay Cobbles (or Setts): A Step-by-Step Guide

Thinking about using cobbles for your next garden project? Great choice. Cobbles — also called setts in the trade — are versatile natural stone blocks that work brilliantly as patio edging, decorative borders, and even full surfaces.

The best part? Most DIYers can lay cobbles in a single weekend. If you can mix mortar and use a spirit level, you’ve got the skills to get it done.

At Primethorpe, we tend to call them cobbles, but you might also hear “setts,” “cobble setts,” or even “set squares.” Whatever the name, we’re talking about the same thing: strong, natural stone blocks that look great and last for years.

Step 1: Plan Your Layout

Every good project starts with a plan.

• Sketch your design – decide where you want cobbles to go: edging, a border, or a decorative line.
• Mark the area – use a string line for accuracy (best for straight lines) or spray paint for curves.
• Get your tools ready – shovel, rake, mallet, spirit level, and sand/cement mix.
• Mix ratio – we recommend 4:1 sand to cement for strength, or 6:1 if you’d like more drainage.
• Order a little extra – cobbles are hand-quarried and can vary slightly in thickness. Having 10% more covers you for cuts and natural variation.

Step 2: Prepare the Base For Your Cobbles

The base is what keeps everything solid. How deep you go depends on the project:

• Patio edging & borders – excavate to around 100 mm.
• Driveways – excavate at least 200 mm. This needs to support vehicle traffic, so if you’re tackling a driveway, we recommend hiring a professional.

Once excavated:

• Fill the depth with MOT Type 1 hardcore.
• Compact it with a wacker plate (or a manual tamper for smaller edging projects).
• Aim for at least 50 mm of compacted hardcore with another 50 mm working depth for borders.

For borders and edging, a solid mortar bed alone may be enough for small DIY projects. For driveways, though, a properly compacted sub-base is non-negotiable.

Step 3 - Lay The Cobbles

And the fun part! There are 5 simple things to follow when laying cobbles

Step 4: Jointing & Finishing

Once the cobbles are in place, fill the gaps to lock everything together. Here's a handy comparison table if you are unsure which option might be best for you:

Option	Key Features
Jointing compound (best for DIY)	Pre-mixed, easy to apply with a brush or squeegee Excellent drainage and quick curing (usually 24 hours) Use plenty of water as you work to avoid resin film forming on the cobble surface
Sand & cement mortar (traditional)	Strong, but trickier: mix yourself and apply with a pointing trowel Must clean as you go — mortar residue can stain natural stone

Don’t forget the haunching: On the outside edge of your border, add a hidden wedge of mortar. This anchors the cobbles against the foundations and stops them from shifting over time.

Step 5 - Curing & Aftercare

Now if you want your new work of art to stand the test of time, it's important to know your job is never done! There a few things you can do once or twice a year that will ensure your project will last as long as you do!

Curing:

• Mortar joints: Allow at least 7 days before foot traffic and 2 weeks before vehicles.
• Jointing compounds: Normally set in 24 hours, but give the mortar bed beneath plenty of time to cure.

Aftercare:

Once installed, cobbles are super low-maintenance. Just:

• Sweep regularly to prevent dirt build-up.
• Spray a weed killer every few months as a preventative measure.
• If joints crack, simply top up with a jointing compound repair kit — it’s a quick afternoon job.

Pro tip: Choose a jointing compound if you want easy future maintenance. It makes repairs and touch-ups a breeze.