What aggregate size goes in Ottawa paver bedding sand?

Paver bedding sand in Ottawa should be fine, angular sand with particles ranging from 0.02mm to 2mm, conforming to CSA A23.1 concrete sand specifications. The most commonly used bedding sand is concrete sand or mason sand, which provides the right balance of compaction and drainage for Ottawa's freeze-thaw conditions.

The particle size is critical because it affects both drainage and stability. Sand that's too fine (like play sand or fine masonry sand) retains water and creates drainage problems, leading to frost heaving and paver movement during Ottawa's 50+ annual freeze-thaw cycles. Sand that's too coarse won't provide adequate bedding support and allows pavers to settle unevenly under traffic loads and snowplow pressure.

Concrete sand is the gold standard for Ottawa interlock installations. It typically contains particles from 0.15mm to 5mm, with the majority falling in the 0.25mm to 2mm range. This gradation allows water to drain through while providing excellent compaction and leveling properties. The angular particle shape (as opposed to rounded river sand) creates better interlocking between grains, reducing settlement and providing a stable bedding layer.

Avoid these common mistakes with bedding sand in Ottawa: Never use fine sand, play sand, or sandbox sand — these retain moisture and cause frost problems. Never use limestone screening or stone dust as bedding material — while these compact well, they become impermeable when wet and create drainage issues. Never use unwashed sand that contains clay or silt particles — these fine materials clog drainage and promote frost heaving.

The bedding sand layer should be 25mm to 40mm thick after screeding and before paver installation. It's screeded level using screed rails, then pavers are laid directly on the uncompacted sand. The sand compacts and conforms to the paver bottom during final compaction with a plate compactor. In Ottawa's clay soil areas (Barrhaven, Orleans, Gloucester), proper drainage through the bedding sand layer is especially critical to prevent water buildup that leads to frost damage.

Professional contractors typically source bedding sand from local aggregate suppliers who understand Ottawa soil conditions and can provide properly graded, washed concrete sand. The sand should be delivered dry or allowed to dry before installation — wet sand is difficult to screed level and doesn't compact properly under pavers.

For interlock paver installation, this is definitely hire-a-professional territory — proper base preparation, sand gradation, screeding technique, and final compaction require specialized knowledge and equipment to ensure your investment survives Ottawa's brutal winters.