This client in Waterloo reached out to us to have an independent patio build off of their deck and bordering their garden area. They wanted a simple place for them to be able to have a table and chairs for them to enjoy. They also really liked the look of square cut natural stone. This quickly turned into a difficult project as there were two tree stumps we discovered in the excavation process. Something that requires extreme care when removing because any organic material remaining in the base would eventually decompose and settle. Especially something like a dead tree that would rot away.
We began this project by squeezing in our machine to the backyard. Because of this tight squeeze we decided it would be best to keep that machine in the backyard rather than running it in and out of the backyard and disposing of the excavated material. So we loaded up wheelbarrows in the backyard and took it to our disposal bin in the front yard. After digging a little bit we discovered the tree stumps. Eventually we called in a stump removal company to be able to easily grind down these stumps to nothing along with their tree root system. What we were left with was a multitude of wood chips that needed to be excavated and removed.
The problem with this is that we were about 2 feet in depth after our excavation from the top of our patio. This means that we needed to bring the same amount of material in our base to the backyard to prepare our base. We began this process by compacting our subsoil and then laying a woven geotextile throughout the area. This reinforces our base material while also separating it from our subsoil to ensure there is no contamination between the two. We wanted the added stabilization considering we had dug so deep and were preparing a dense graded base on top.
We had our base material dumped on the driveway and continued bringing back the material loading it up on the driveway into wheelbarrows and dumping it on top of our geotextile. About half way up we laid out a layer of biaxial geogrid. This material is a mesh-like material that interlocks the aggregates of our base material and stabilizes the base that we put on top. We then prepare the remainder of our base, compacting as we add to it.
In this specific case for our bedding layer we choose to use concrete sand. This is because with this square cut natural stone our client wanted them laid as tightly as possible. Therefore we wanted a fine bedding layer that would work best for these tight joints. The alternative is to use High Performance bedding which is a 1/4″ angular crushed clean chip, but we do not like using this for tight joint materials. We screed this material with a slope towards the back corner of the patio where the water can drain off of the surface. We could not slope it to the opposing corner because the garden bed would be slightly higher than the patio in this area and we did not want to build up water there.
With our bedding layer screeded, we can then start to lay this square cut natural stone. We begin laying from one corner and work our way throughout the patio. This material is a little bit more difficult to lay because the natural stone is not perfectly the same height from one piece to the next. It requires some levelling from one piece to the other which may mean after we lay it on our bedding layer we add a little bit more bedding material or remove a little bit and use a rubber mallet to hit it down into the bedding layer.
With our patio laid, we then can install our edge restraint and polymeric sand. The polymeric sand solidifies, but remains flexible so any movement in the patio will not crack it. This gets swept into the joints and we vibrate the square cut flagstone with a mallet to get the sand to go down to the bottom of the joint. We then blow off the surface to remove any remaining residue and activate the sand with a shower setting on our hose.
With this our client is left with a beautiful square cut natural stone patio for them to enjoy for years to come!
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