Laying Block Paving on Grano Dust (vs Sharp Sand)

Sharp sand is being used under the pavers forever. Grano dust is another aggregate that’s being used under the pavers and many people prefer it to lay block pavings.

If you ask people about what to use, the majority of them will still say sharp sand but many will say grano dust too. At the end of the day, the final decision depends on you on what to use.

And, if you’ve made your decision on what to use and you’re using grano dust, this post covers further questions that you might get regarding the grano dust.

At the same or a little more cost, grano dust is more permeable than sharp sand hence why it’s used under artificial grass so it doesn’t bog up like sharp sand and if it creates a more firm, solid laying course then why not.

This is exactly what is also mentioned in our DIYers Block Paving Cheat Sheet here which you definitely should check out if you are a DIYer doing block paving by the way.

Depth of Grano dust under block paving

The ideal depth of grano dust to have under block paving is 30-40mm, and some paving installers even go up to 50mm if they see any requirement for it depending on the ground conditions or the purpose of the paving to be installed (either a block paved patio/outdoor space or a heavy vehicular traffic driveway).

If it’s mostly a patio or outdoor space, even 30mm is the best and there’s absolutely no need to go more than 50mm in most cases, even if the block paving is going to receive vehicular traffic.

How much grano dust do I need?

Of course, other than the size of your block paved patio or driveway, the quantity of aggregates you’ll be needing for the job also depends on the thickness or depth that you want for your sub-base or laying course.

The same is the case for grano dust that you’re going to use for the laying course instead of the sharp sand. There’re many aggregates calculators available online that will help you to find the approximate quantity of granite dust needed for your particular job.

On average, 1 bulk bag that’s 1 ton of granite dust covers around 7-10m2 depending on the depth of the laying course that you need. So for example, for an area of around 40m2 that needs to be block paved, you’ll need 3.5-4 tons of granite dust for a 50mm thick laying course.

Grano dust is also available in the packaging of lesser quantities other than those standard bulk bags (1 tonne or 1000 kg) in some places in case if you have a considerably small job to do.

Compacting Grano Dust for laying Block Pavers

After nicely compacting the sub-base (Mot type 1), now it’s the turn of the screed layer (grano dust in this case). Everyone has different methods, meaning some people do certain things differently throughout the job based on their past experiences.

Spread the grano dust about half-inch higher than the finished height you want. For example, if you’re going for 50mm thick bed for laying the pavers on, add about 60-70mm of grano dust and wack it completely down to the finished height.

Before compaction, it’s recommended to wet it down so it compacts and binds well in a couple of passes of the wacker. It’s recommended to have at least 2 passes, and if you’re a DIYer or have never done a block paving with grano dust, consider getting 3-4 passes with the wacker for better compaction.

Screed it leaving around 5mm higher than the final height for the final wack with kiln dired sand after laying the pavers. You are always welcome to top it up and compact again if needed or remove the excess anywhere required just making sure that you’re screeding 5mm higher and the pavers would be 5mm higher than your final height.