Building a Patio in Alberta

Buiding a patio in Alberta can be a daunting task that is labour intensive and difficult to get right. If you are interested in a D.I.Y. patio project, we will outline 8 key steps to ensure you install a patio that will last.

Step 1- Plan your patio: You should plan in advance exactly where you would like your paving stone patio. Use marking paint to mark out where your patio will go, however your outline should extend an extra 150 (6″) further than your patio will finish. This additional space will be crucial to build your base beyond the extent of paving stones to ensure the edges of your patio do not buckle.

Step 2 – Excavate: The depth of excavation should be a minimum of 200mm (8″) below finished grade (measured from the lowest point adjacent to your patio). A simple tip when hauling out the soil is to start at the furthest point from where you will be stockpiling the soil and work your way to the closest point.

Step 3 – Prepare the sub-grade: Use a Jumping Jack to compact the sub-grade. Once the clay has been compacted tightly lay Geo-fabric across the entire extent of the excavated area of the patio, leaving a couple of extra inches of fabric. Use landscape staples (spaced 1000mm or 3′ on center) to pin the fabric tightly to the ground.

Step 4 – Lay and compact the base: When laying the base it is important to understand the grading in the yard. A patio should have a minimum slope of 2% (2′ of rise over 100′ of run) to ensure water does not pool. Use 10mm diameter crushed rundle rock and spread evenly over the entire excavated area at a 125mm (5″) depth. As a tip to make grading and constant depth easier to accurately calculate, use 1″ diameter metal conduit as a guide when screeding the rundle (as shown in image 5 below). Once the base is evenly laid and graded, lightly wet the the rundle rock and use a tamper to compact the base. Typically 95-98% standard proctor density is advised for compaction. Simply put if you have achieved the proper compaction, you should be able to stomp your heal into the base and not see a mark. When you are not sure if the base is compacted enough, tamp it some more (it is nearly impossible to over tamp a base).

Step 5 – Prepare the base to begin laying stones: Ensure there are no bumps, pitches, dips or waves exceeding 1/8″. Once your base is prepared use the metal conduit bars again to lay 1″ depth of masonry sand. Use a trowel to fill in the holes left by the conduit bars, ensuring the sand looks completely uniform and smooth.

Step 6 – Lay the stones: Now that the base work is done you can begin to lay your chosen paving stone. The important thing to remember is to keep off of the paving stone as much as possible until properly set. Use a sheet of plywood to stand on while laying the paving stones to help distribute your weight and not buckle any of the paving stones. For any required cuts you can mark the stones with soap stone or a carpenters pencil and make the cut with a diamond bladed wet saw.

Step 7 – Restraining the paving stones: Use an edge restraint called ‘Snap Edge’ and 12″ spiral nails every 1-1.5′ to hold the paving stones in place. Be sure the final height of the edge restraint does not come higher than half way up your paver.

Step 8 – Fill in the joints with Polymeric sand: Spread polymeric sand over your patios and sweep into the joints between paving stones. Once all joints appear to be filled, lay plywood sheets over the patio and run your tamper over the plywood. Remove the plywood and top up the polymeric sand again. Once all the joints are filled, remove all excess polymeric sand and lightly wet the patio using a ‘mist’ or flat stetting and wait 24 hours. Be sure to top up the polymeric sand annually to ensure no weeds grow between your paving stones.

Enjoy your patio, and keep bringing your outdoor living dreams to life!

William Packolyk, BLarch, Associate AALA