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How to Install a Flagstone Driveway

Steinpflaster image by MIR from

Traditional driveways have long been boring expanses of grey concrete, a stone surface adding little to the curbside appeal of a home. For a change of pace that adds to the appearance of a property, a flagstone driveway makes a good alternative. It has a look that's incomparable to driveways built of other materials. The natural stones fit together haphazardly, with joints carefully mortared in place. With control over the shapes and shades of stones used, you can create a pattern that's pleasing to the eye while the stones themselves provide the strength to support vehicles.

Design the driveway using a piece of graph paper and a pencil. Draw the driveway to scale so that you can calculate the area you need to cover and purchase enough stones. Work out the area by multiplying the length of the driveway by the width of the driveway.

Purchase the flagstones for use as the driveway surface. You'll need stones that go along with the look of your home as well as being thick enough to support standing and moving vehicles. Purchase stones between 3 and 6 inches thickness, with thicker stones needed if you intend to support larger vehicles. Choose stones with inherent strength like sandstone, yorkstone or cleft slate.

Used stones are less expensive and already have their final color but may be difficult to find in the quantities and sizes needed. Order new stones cut to thickness if used stones are unavailable. Purchase an additional 10 percent by area to account for broken stones of difficulties in fitting.

Mark out the area for your driveway according to your design plans using lawn flags thrust in the ground along the proposed driveway contours. Dig a hole 10 inches deep for the foundation of the driveway using a shovel. Compress the soil on the bottom of the hole using a plate compactor rented from an equipment rental shop or home improvement store.

Place a 6-inch layer of MOT/crusher run in the bottom of the hole. MOT/crusher run is a combination of various sized gravel. Use the plate compactor to compress the gravel to a four-inch thick layer.

Place a 4-inch thick layer of sharp sand, not building sand, which has a tendency to wash away with heavy rains, onto the layer of gravel. Run the plate compactor over the sand, reducing it to a 2-inch layer.

Mix the mortar with water in a large bucket using a drill with a paddle bit attachment. Add water to the mix until you achieve a consistency like that of peanut butter.

Place a layer of mortar 1-inch thick on the sand layer to serve as a bed for your flagstones. Spread the mortar using a steel trowel and then lay the flagstones into the mortar with a joint measuring 1/5 inch between stones to allow for expansion of the surface during weather changes. Butter the edges of the flagstones with mortar and press adjacent stones together to form a bond between neighboring stones. Fill the joints between stones with mortar until the joint is level with the surrounding stone surface. Remove excess mortar from the stone faces as you place the stones.

Tap the stones into the mortar bed with a rubber headed mallet to create a level surface. Check for level with a carpenter's level by placing the level across adjoining stones and making sure the stone surfaces are even. Make any leveling adjustments needed, using the mallet to press uneven stones further into the mortar bed, or adding additional mortar to the bottom of stones as needed to raise them to a uniform surface.

Cut the stones when necessary for fitting or for the edges of the driveway using a skill saw with a diamond tipped blade. Mark the stone along the cutting edge with a piece of chalk and then cut along the mark with the skill saw. Attach a water hose to the saw to suppress the dust created when cutting the stones. Wear a dust mask to provide further protection for your lungs, and safety goggles for eye protection during cutting.

Cover the driveway with waterproof insulating blankets to retain heat generated as the mortar cures. The heat helps the mortar strengthen. Remove the blankets after 48 hours and allow the mortar to finish curing for the length of time suggested by the mortar manufacturer.

Seal the surface of the flagstone driveway with stone sealant formulated for use on your particular driveway stone type. Spray the sealant over the entire surface of the driveway, including the mortar joints. Allow the sealant to dry according to the manufacturer's instructions before using the driveway.

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