FALLBROOK – Using sand for a stone patio or walkway is referred to as ‘dry construction.’ That is when natural stone pieces are installed on sand instead of adhered to a concrete slab with wet mortar. Dry construction is not as permanent; however it is a bit easier, and a lot more forgiving.

This application is primarily for use with flagstone (a natural stone with two parallel sides) of random shapes without cutting to shape or size, though this same process can be used for setting broken concrete or concrete pavers as well.

Pre-planning is key

First one determines the size and shape of the new patio or walkway. Removing sod or starting with a new undisturbed area will dictate how much excavation will be required and how much sand and/or gravel and flagstone will be needed.

Here are a few things to consider when selecting stone:

Different kinds of stone present different challenges. Some types will not be available in one’s preferred sizes or color.

Some stones, such as sandstone, are much easier to work with than others if they need cutting. Whether the area is in the sun or shade may be a deciding factor if using a quartzite which has a reflective quality.

Choices for filling in the joints (space between the stones) include decomposed granite (D.G.), pebbles, gravel, and dry mortar. Some kinds of plant material: moss, dicondra, dymondia, creeping thyme or sedum can be used instead. This choice will determine how much water and maintenance are required.

Generally speaking, one will want to use a minimum 1.5 inches to 2 inch thick stone and the stones are easier to piece together if they are at least 12 x 16 inches or larger. Stone is heavy, so even at this size a piece may weigh as much as 30 lbs. Some help may be needed. Esthetically, a combination of small, medium and large stones is more pleasing.

Getting started: remove the old lawn

First off, when removing an old lawn or any part of the area, consider that the more time spent in the beginning will have greater benefits later.

Start by simply letting the grass die out. Or to speed up the process, spray with a weed-killer such as Round-Up first. Let this go for a week or so. Then cut the old sod and remove in chunks (a perfect addition to a compost pile). Ultimately, it is a good idea to excavate to a minimum depth of 4 inches as one may be adding as much as 2 to 3 inches of gravel and sand and then the 1.5 to 2 inch thickness of flagstone on top.

Watering this area encourages any leftover weed and grass seeds to sprout. Once they begin to grow, spray with Round-Up again and cover the area with a heavy black plastic. Weigh down the edges of the plastic with rocks or sand bags and let this sit for at least three weeks (during the cool months, leave longer).

Preparing the area

Lay out the area using a simple garden hose or stakes and string to get the desired shape and Advertisement

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Level the area using a carpenter’s level and tape measure. Remember, if the new patio or walkway is next to a structure or existing concrete slab, a slight grade away from the feature encourages adequate drainage.

Lightly moisten and tamp down the area. It is not critical to add weed cloth if the previous steps have been followed. There shouldn’t be any growth beneath the stone.

Add edging materials: stone, plastic lawn edging, brick, or bender board. Here again remember the depth of the excavated area. The top of the edging should be level with the top of the flagstone once installed, unless the design dictates otherwise.

Installation

Shovel a minimum of 2 inches of concrete sand into the area. Moisten with a fine spray and tamp down. Check the levels.

Select the chosen pieces and do a pre-layout. This is the fun, creative part and will save a lot of time. It is easier to move and or change the stones around before actually doing the leveling and setting in place.

Start by working one’s way out or away from any structure or existing features: concrete slabs or driveways, etc.

Once the stones are down in the desired layout, one starts the actual placing and leveling.

Add or subtract moist sand beneath the stones, keeping a bucket of moist sand nearby for this use. One may need to rearrange or replace some stones, usually due to making minor adjustments such as changing the width of the joints or just because one stone may look better in that space than another.

Tamp each laid stone with a rubber mallet and check levels regularly.

Leave at least 1 inch of the flagstone exposed above the sand base. This is the space that will be filled with whatever material is chosen for the joints to help keep the stones in place and stable.

After all the stones are down and in place, spray with a fine mist to moisten and settle everything.

The final step is filling the joints. If using D.G., use a bucket to gently pour into the joints. Sweep the excess into joints or off the patio area. Water with a fine spray and be sure that the water penetrates the full depth of the joint. The D.G. will harden once it dries. There will continue to be some small grit or rock on the surface and some D.G. will have more grit than others. Sweep off any excess after the area has dried.

If using gravel or pebbles for the joints, shovel or use a bucket to pour into the area and then sweep into joints and remove excess.

If adding plant material, address irrigation options prior to setting the stone. Purchase flats of the chosen plants. Sweep a small amount of peat moss into the joints then cut the plant material into strips the width of the joints. Gently tamp the plants into place and spray with a fine mist.

Information above provided by Southwest Boulder & Stone of Fallbrook. Questions may be directed to (760) 451-3333.