Dry Laid Bluestone and Installation Methods

by Karen
(Chicago)

Here is a questions about dry laid bluestone and installations methods.

I have a 12' x 16' front yard and a 12' x 18' backyard. I'm planning to plant both this year and then add flagstone areas in both next year. I'll end up with patios about 8' x 12' in each. Given the tiny area involved I'm planning to do this myself. I want to use natural irregular full range bluestone with moss in the gaps. So: how deep do I need to excavate? Since I'm saving up for this, how do I estimate cost? I live in Chicago and I am thinking about buying direct from the local Illinois quarries to save a bit. Thanks!

ANSWER

Hi Karen,

Do you want moss to grow between all of the stones or just some of them? Is your area shady, because that is what you need for moss to grow? It must be shady and on the damp side.

Set the stones on firm ground, excavating only the depth of the stones. If the stones are 2", excavate two inches. This will allow you to have moss growing in between the stones all over.

The typical dry laid method will most likely not work if you want to grow moss. Here are two pages showing how that is done. They show pavers, but the same method is used for bluestone.

Paver Installation

Building A Patio

The reason this is not a good method if you want to grow moss is the following. As mentioned, moss likes it damp and shady. The sand that is installed beneath the bluestone allows for very good drainage, keeping the area dry, not damp.

If your area is VERY wet, you could use the second method. But as long as your ground is firm, just setting the bluestone on the slightly excavated area will work. And easier for this small area!

Here are some walkway pictures using casual stones. I am sure they were just set on the ground, with slight excavation.
Stone Walkways

One last idea is to use the dry laid method (with the stone beneath the patio, but leave some areas filled in with soil for the moss. These should be where the larger gaps in the stones are to allow for better water retention.