DEAR TIM: I’ve decided it’s time for a patio in my rear yard. After visiting a local business that sells a vast variety of patio pavers, I’m ready to start. Do you think this is a real DIY job, or am I being too ambitious? After watching a number of videos on YouTube, I’m more confused than ever about the best base material. Have you installed these patio stones, and what method do you recommend? Are there any hidden surprises with precast concrete patio pavers? – Sue T., Racine, Wisconsin
DEAR SUE: You must have been in contact with my wife. She loves patios and has been wanting one here at our New Hampshire home for a few years. I had constructed a huge brick patio for her many years ago at our last home and she misses it.
We did the same thing you did just a week ago. We went to a large local business that stocks just about any type of natural stone or precast concrete paver that’s available. It was exciting for me to see how the patio paver industry has matured. I can clearly remember how limited the selection was many years ago when the first generation of this building material hit the marketplace.
Kathy decided to go with a stunning paver that has a textured top surface that resembles slate. This design creates a random texture with deep shadow lines that might fool some into thinking that it’s real slate. Be sure you visit several stone and paver suppliers to see all the different patterns, colors and textures that are available. Not every business stocks every precast concrete paver.
I happened to watch some of the videos online and shook my head. Installation methods meant for city streets were being touted as the way to do a small residential backyard patio that may have a lawnmower ride over it instead of a 40-ton loaded concrete truck!
Ask five different paver contractors the way to install the paving stones and you might get five different methods. What really matters is the strength of the underlying soil under your patio, the size of the pavers you intend to use and how much concentrated weight will be placed upon any given paver.
Precast pavers that have to support the weight of cars, trucks and the like need a deep compacted base of crushed gravel. Compacted concrete sand is then placed on top of this. A thin final layer of setting sand is the actual surface you place the pavers onto.
Larger paving stones act like building footings. They spread the weight put upon them across a greater area. This is why Kathy and I decided to use a three-piece set of pavers where the largest one measures 16-by-24 inches. Because our patio measures 10-by-24 feet, the large format also looks more to scale.
Here’s something that many installers seem to forget. You can drive your car or truck on many sand beaches here in the USA. I’ve done it with my full-sized pickup truck! The vast majority of sand you see is just small pieces of rock. On some beaches it can be tiny pieces of sea shells or broken coral. In other words, compacted sand can provide a sufficient base for a paver patio that’s just going to have you walking across it.
I fully believe if you’re in decent physical condition you can do this entire job yourself. Your only limitation is going to be if you can lift and hold the paving stones with your two hands. You need to be able to place the pavers very carefully so they drop onto the final layer of sand as flat as possible. When you visit the businesses that sell the stone, try to lift the largest paver you’re thinking of using.
I’ve installed many paver patios. As you might suspect, I decided to test different methods for patios trying to discover the best method requiring the least amount of work. Using my geology degree and some common sense, I finally settled on using concrete sand under my patio pavers. The method I’d use for a paver driveway differs from what I’m about to share.
Just a few days ago I excavated the soil and then used a hand tamper to compact any disturbed soil. I then set wood forms on the soil that extended a minimum of 3 inches beyond the edge of the finished pavers. Just as roads have shoulders to support the pavement, I wanted my compacted sand to extend beyond the patio edge.
I like concrete sand because it has a wide variety of rock particles in the sand that range from fine sand all the way up to stones that are about the size of green peas. This sand is easy to shovel and place. I put down 3 1/2 inches and used my hand tamper to compact it. The tamper compacted this at least 3/4 of an inch.
I then used my garden hose with the garden nozzle set to shower to thoroughly wet down the compacted sand. The water flowing through the sand further consolidates the sand just as the sea water does at the beach. The next step is to place the final thin layer of concrete sand on top of the compacted sand. You set your pavers on this layer gently, making sure the edges of the pavers touch one another and they are set flat on the sand.
The final step is to use new polymeric colored sand to fill the joint between the pavers. This special sand helps prevent weeds from growing in the cracks. My only complaint about the precast colored concrete pavers is they eventually change color as the colored cement paste wears off the top surface of the pavers. Do not pressure wash your paver patio, as this accelerates the loss of the colored cement paste.