Laying Slate or Flagstone on an Outdoor Patio

Masonry paving materials such as slate and flagstone offer a patio a natural appearance, enabling it to blend in seamlessly with grass lawns, fish ponds, gardens and potted plants. Flagstones present an irregular appearance, while slate is flatter and more uniform, but both are laid out in a similar fashion. Whichever paving material you choose, the only real difference in procedure will be how the masonry is cut to fit your patio design.

Things You'll Need

• Stakes
• Rubber mallet
• Mattock
• Shovel
• Sand
• Tamper
• Iron rake
• Scrap 2-inch-by-4-inch timber
• Carpenter's level
• Circular saw with masonry blade (slate only)
• Hammer (flagstones only)
• Chisel (flagstones only)
• Push broom
• Garden hose

Instructions

1. Drive marking stakes witha rubber mallet along the outside of the area where you want the patio to go. Tie string between each stake to check for straight lines, if straight lines are desired, and adjust the stake placement as necessary.

2. Excavate the work area with a mattock and shovel. Dig down three inches plus the thickness of your average paving stone. For slate pavers that are one inch thick, the depth is four inches. For flagstones averaging two inches thick, the depth is five inches.

3. Fill the patio bed with an even layer of sand three inches deep. Dump or shovel the sand in, and then even it out with an iron rake.

4. Compact the sand with a dirt tamper or a power tamper. Check the surface for evenness by placing a long 2x4 board across the sand, and move sand around with the rake or add/subtract sand with a shovel to make adjustments. Compact any adjustments.

5. Lay the slate pavers or flagstones. Fit the slate pavers together so the sides are flush, and set the flagstones down with a one-inch wide gap between each stone. All the slate pavers should be flush, although laying irregular flagstones inevitably entails leaving some large gaps here and there. Settle each stone in place by tapping the top with a rubber mallet before laying the next stone.

6. Place a carpenter's level across the top of recently laid slate pavers for every second or third stone to ensure the stones are level. If they are not, pull the uneven stones back up and add or subtract sand in that area. Skip this step for flagstones.

7. Examine your patio once most of the stones are laid, and then move and re-lay stones as necessary to create a better pattern. As a rule, if you need to cut smaller flagstones or slate pavers to fill gaps, these gaps should be in the middle of the patio and not on the outer perimeter.

8. Cut flagstones and slate pavers to fit irregular areas. Cut slate by drawing a line across the top with a pencil to mark where you need to cut it, and then make that cut with a circular saw fitted with a masonry blade. For flagstones, draw the cutting line on the top and bottom and cut a groove along this line with a hammer and chisel. Fracture the rock along the cutting line by striking that groove hard with the hammer and chisel.

9. Lay the newly cut stones in any gaps..

10. Dump more sand on top of the paved surface, and force it into the joints between the stones with a push broom. Even with the slate pavers will have small cracks between the stones. Spray the patio with a garden hose to wash down the sand and compact it in the joints between stones. Add more sand and wash that down too, continuing until the joints are full of wet sand.

References

• Popular Mechanics; "How to Build a Stone Patio;" Steve Willson.
• "Popular Mechanics: Home How To;" Albert Jackson, et al.; April 2000
• The Family Handyman: How to Build a Stone Pathway