What's a good geotextile fabric to use under Ottawa pavers?

For Ottawa interlock installations, use a non-woven geotextile fabric with a minimum weight of 140 grams per square meter (4 oz per square yard) that meets AASHTO M288 Class 2 specifications. This provides the right balance of soil separation, water drainage, and puncture resistance for our freeze-thaw conditions.

Non-woven geotextile is essential under Ottawa pavers because it prevents the migration of clay subgrade soil up into your granular base while still allowing water to drain through. Ottawa's prevalent clay soils (especially in Barrhaven, Orleans, Gloucester, and Riverside South) expand when wet and contract when dry. Without geotextile separation, clay particles work their way up through the base material during freeze-thaw cycles, contaminating the granular base and creating soft spots that cause paver settling and heaving.

The fabric acts as a stable platform that distributes loads more evenly across weak subgrade soils. During Ottawa's 50+ annual freeze-thaw cycles, the geotextile maintains separation between your expensive Granular A and Granular B base materials and the native clay below. This prevents the "pumping" action that occurs when heavy loads (vehicles, snow plows) compress contaminated base materials.

Choose needle-punched non-woven polypropylene or polyester fabric rather than woven types. Non-woven fabrics have better soil retention properties and conform better to uneven subgrade surfaces. Woven fabrics can create preferential flow paths that allow soil migration. Look for fabrics with an apparent opening size (AOS) between 70 and 100 sieve size - small enough to retain clay particles but large enough for proper drainage.

Installation is critical for performance. The geotextile should be placed directly on the prepared subgrade before any granular material. Overlap seams by at least 300mm (12 inches) and avoid wrinkles or folds that create weak points. When placing your first lift of Granular B, use care not to puncture the fabric with sharp stones - place material gently and avoid driving equipment directly on the fabric.

Popular brands meeting Ottawa requirements include Mirafi, Propex, and Typar geotextiles available through landscape supply yards like Rideau Paving Stone, Expocrete, or Permacon dealers. Expect to pay $0.50 to $1.50 per square foot installed. While this adds $200 to $600 to an average driveway project, it's essential insurance against base failure that would require complete reconstruction.

When to hire a pro: Geotextile installation requires proper subgrade preparation, accurate fabric placement, and careful granular placement techniques. Most interlock contractors include geotextile as standard practice on Ottawa clay soils - if your contractor suggests skipping it to save money, find a different contractor.

Need help finding a qualified interlock contractor? Ottawa Driveways can match you with local paving professionals who understand Ottawa's soil conditions and use proper geotextile installation techniques.