Larsen Landscape | Blog

FLAGSTONE PAVING – HOW TO

Flagstone paving can be done in several ways.  This article is about the highest quality approach.

If you want your new flagstone patio or walkway to have that top quality look and stay that way, then this is the procedure to follow.  First, you start with removing the soil in the area to a depth of about 8 or 9 inches below where you would like the final patio level to be.  Then put in a couple of inches of sand and, while moistening lightly with water from time to time, run a vibrating compactor over the sand to pack it in tightly.  This really presses the sand down so there will be no sinking later.  The sand acts to “float” the concrete which will go over it so if the earth moves when it gets wet and then dries out the sand tends to move rather than the concrete.

Next, put some steel reinforcing bars in place and pour the concrete base over the sand.  Typically, this is laid in at a depth of about three to four inches.  The finish doesn’t have to look perfect but the level does have to be fairly accurate to help with the drainage grade you will need to achieve with the final stone layer.  We also use a product called micro-fiber, which gets mixed right into the concrete for extra strength.  The primary strength of your patio is from the concrete under the stone – and if done right will give you a patio that will never crack or sink.

Finally, it is time to add your flagstone.  In the best work, the random pieces are roughly fitted together by eye, one at a time, and then trimmed with a diamond blade saw to have joints which are random, but at the same time, do not have much variance from one joint to another.  In other words, if all the joints are a little under or a little over say half an inch, then it is a topnotch job of fitting.  This is where a lot of skill comes in.

Flagstone Entryway in Thousand Oaks by Larsen Landscape

The stones are set on a high quality mortar (we use a premixed product called Spec-mix which really grabs and holds the stones).  A bubble type mason’s level needs to be in constant use for this part to ensure an even surface that drains off the rain and sprinkler water.  Getting the drainage right and avoiding puddles is probably the trickiest part.

Finally, use a grout bag (sort of like a cake icing bag used for masonry grout) to squeeze the grout into the joints.  The nicest look is achieved by using silica sand mixed together with regular cement at a one to one ratio.  The mortar is scraped off level with a trowel while it is still somewhat wet and then a sponge is used to even it out.  The sponge needs to be damp but not soaking wet for this.  The sponge is also used to clean the stone at the same time and usually the bucket of water being used for this part has to be changed frequently.

If you want to add a clear sealer to the stone to really bring out the color (and keep softer stones from being eroded by water), this can be done after the grout is dry (a day or two later).  Be sure to add an anti-skid powder to the sealer to avoid people slipping after a rainstorm.  Some of the clear sealers can be like ice when they get wet.