Featured Project 2
New Patio Project
This site had a small patio that could barely fit the clients’ patio table and chairs. It was a constant headache when they entertained. The poured-in-place steps were also pulling away from the house because they were not pinned to the existing foundation. They had been poured as one unit with the patio. The slope off of the edge of the patio was allowing run-off to pull the patio and steps away from the house.
Before any demolition can take place, the project must be laid out. For this project, it was crucial to shoot grades to calculate how much gravel fill was necessary to get the new, expanded patio to the proper elevation and to set end points to ensure the patio would have the appropriate pitch away from the house.
Since the patio had an expansion joint and the steps were improperly mounted to the house, we were able to use a skid-steer with forks to remove large sections of the patio at a time. However, we discovered another issue once the patio and steps were removed. As a new-construction home, a large amount of clean stone had to be filled beneath the patio in order to get it to the right elevation. As the backfill around the home settled- as is typical during the next 3-5 years after a new home is completed- the gravel fill also began to settle. Without any anchoring to the house foundation, this is likely what caused the patio and steps to pull away from the house. If you have a poured concrete patio on new house with a basement, then be vigilant of any problems during the 3-5 year post-construction window.
The lawn immediately off of the patio had pitched to a drainage swale in the yard. Since we were expanding the patio to be closer to that drainage swale and we were bringing the new patio elevation up over 15” from the existing grade, we had to add an abundance of soil to retain the compacted gravel for the new patio. When installing any hardscape, fill should be installed on ONLY undisturbed soil and the fill must always be gravel. Soil should NEVER be used to backfill for a new hardscape item because backfilled soil is clumped and it will never be compacted back to the state in which it was before it was disturbed. If soil is used, then you will have settling. Our backfill was soil because it was used in order to hold back the compacted gravel upon which the patio would be built and not to hold up the patio. In order to ensure that the new soil “berm” was stable, we ran a plate compactor over the soil as we filled it in layers.
Once the soil fill could support the gravel fill, we began installing it in layers in order to maximize its compaction. The gravel base should never be compacted in layers greater than 4” thick. If a contractor just dumps 8” of fill and starts compacting the gravel, then it will never meet the compaction of thinner layers thus risking the stability and longevity of your patio.
After the gravel is compacted and an appropriate pitch is achieved with the base, then the sand setting bed is installed. Sand screeding rails are installed, embedded in the sand layer, in order to ensure a proper thickness of the setting bed. A screeding board is pulled across the rails in order to ensure a consistent thickness and pitch of the setting bed.
As sections of the sand setting bed are completed, the pavers are laid. It is crucial to maintain the desired pattern. A banding is a great detail that creates a finished look to the edge of the patio much like trim enhances the walls in a house. Once all of the pavers are laid, then sand is swept into the joints between the pavers. A plate compactor is typically run over the pavers in order to completely set them into the sand setting bed and to vibrate any sand deeper into the joints. If the joints are large, then polymeric sand may be used to finish the top ¼” to ½” of the joints. Polymeric sand contains an adhesive that makes the sand somewhat impermeable. It also thwarts weed grow from the joints. However, during its installation, the contractor must be very diligent that the polymeric sand stays in the joints so that it does not stain the pavers.
Once the pavers are laid, some sort of edging restraint must be installed. A plastic edging with spikes is ideal. It should be installed so that the top edge of the plastic can be covered with soil or mulch so that it is not visible. If the edging is installed with the top of it flush with the top of the pavers, then the edging is too high. It will heave in the winter and before you know it, it will be high than the patio itself. The plastic edging is least likely to creep up to the top of the pavers in areas where the lawn meets the patio. The turf’s root system will grow around the edging and hold it down. However, in a mulched area, the edging can tend to rise up through the years and it may need to be adjusted to be back below the top of the patio. Although this maintenance is typically necessary every few years, it is still a better alternative to concrete slapped around the edge of the patio. Concrete is porous and it will absorb moisture. Once freeze cycle and the concrete will crack. Once it cracks it no longer has the strength that it had when it was all one unit. As the concrete cracks elsewhere, it will no longer retain the pavers and the patio will start to separate at the edges. Even though the plastic can heave through time, it still holds the pavers together so that the integrity of the patio is not affected.
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