The Base for a Paver Patio
The base for a paver patio determines whether it will live to be old or die a very young death. Characteristics of a suitable base:
- Woven landscaping fabric – base underlayment
- ABC (or crusher run) – base type
- Compaction – base density
- Thickness – base depth
- Slope for drainage – base grade
- Make it level (relative to your desired slope) – base smoothness/level
Base underlayment – woven landscaping fabric
Don’t forget to install your fabric first. After digging out for the patio, use sod staples to hold down your fabric. Although this step isn’t absolutely necessary, it is highly suggested. It helps prevent your ABC from washing out over time and keeps the ABC out of the dirt. Another name for this special fabric is geotextile. Areas that take on a lot of water will benefit the most from having this fabric underlayment. Make sure it covers not only the bottom but also runs up the sides and extends out a few inches. You can cut the excess off after your project is finished.
Base Type – ABC (crusher run)
It’s been done all kinds of incorrect ways. Just plain gravel is hard to compact and the sand falls down between the stones. Just plain sand on top of bare ground makes your structure weak (to say the least). Concrete can make a good base but is prone to cracking. The base for a paver patio really needs to be ABC (also known as crusher run). Just the right combination of gravel and powder makes for a dense, strong base when it’s compacted correctly. So find the closest landscape material shop and ask for either ABC or crusher run. Remember, Step #2 taught us how to calculate the quantity needed, whether in tons or cubic yards.
Base Density and Depth – Compaction and Thickness
Use a plate compactor to thoroughly compact the paver patio base. Go in different directions to ensure adequate compaction. Don’t forget to compact in 3 inch increments!
If building a paver driveway, you’ll recall that your ABC needs to be 12″ deep, minimum. Alternatively, a paver patio or walkway requires a base depth of 6″ minimum. Shovel your ABC into the excavated area and rake smooth as you go. Stop when the thickness gets to about 3″. You’ll want to compact your ABC in increments of 3″. Any more that that and you risk not compacting thoroughly. Use a hand tamp at the edges if you must. A gas-powered plate compactor, however, rents for about $100 per day. This will make your job not only faster, but will do a better job. Go around the border 3-4 times with the plate compactor and in different directions. Use the hand tamp for places the plate compactor can’t fit. After the border is good and compacted, compact in lines one way a couple times, covering the entire area. Then, compact in perpendicular lines a couple times. Compacting in a cross pattern will this will ensure a more thorough compaction.
The Base for a Paver Patio – Slope and Levelness
Drive stakes in 4 corners of your space. Use string and tie to stakes and raise to exactly 3 and 3/8″ below your finished height. This is given your paver’s height is 2 and 3/8″. Just figure 1″ (for sand) + paver height. Use a line level or transit level to draw level marks on all stakes. You’ll want your patio to slope just enough so that rain water drains off. It should not be noticeable to the naked eye. 1% to 3% is common. Stay closer to 1% if you can. For instance, say your patio extends out from your house into your yard 20 feet. Your pavers need to be 1% lower and in your yard than at your house. Convert 20 feet to inches and you get 20 x 12 = 240 inches. Then, 1% of 240 inches is 2.4 inches. You already have your strings level from house to out in yard and you marked both spots. Now go out into your yard and mark the stake at a spot 2.4 inches lower than the mark that was level. Adjust all string lines accordingly. You’ve just marked, with string, where the top of your compacted ABC must sit. Try to get it as close as possible after compaction.
Conclusion
To conclude, a paver patio is only as strong as its base. Congratulations on learning the right way to build the base for a paver patio. You now have the knowledge to increase your patio’s longevity, strength, resistance to wash-outs, and smoothness. And next you will learn about screeding the sand!