What interlock steps are made of
Interlock steps are built from manufactured concrete step units, wall blocks and coping stones — the same family of products as interlock driveways and walkways. Major lines like Techo-Bloc, Permacon and Unilock make dedicated step units in many colours and textures. Premium lines cost more than standard pavers, and natural-stone treads cost more again.
The result is an entrance that looks landscaped rather than poured. Done well, it blends with an interlock walkway, garden walls and planting beds.
The base is the whole job
Interlock is a flexible system. Each unit is only as stable as the base beneath it. That’s why Ottawa installers build interlock steps on a compacted 10–12 in granular base with edge restraint and polymeric sand in the joints.
Our process:
- Excavate below the soft topsoil and fill.
- Build the granular base in compacted lifts, graded so water drains away from the house.
- Lay the step units and risers, checking every rise against the building code’s limits for a house (125–200 mm rise, 255–355 mm run, risers within 5 mm of each other).
- Set coping and treads with construction adhesive where the manufacturer specifies it.
- Lock it in with edge restraint and polymeric sand.
Code and permits for interlock steps
Interlock steps are a “landscape structure” in the City of Ottawa’s eyes. The City’s advisory is clear on three points:
- Structures that provide access to the house and have more than 600 mm of elevation difference need a building permit and guards that meet the code.
- Structures over 1 m (3 ft 3 in) high need an engineered (Part 4) design.
- Landscape structures shouldn’t be attached to the foundation unless a professional engineer designs the connection.
Even when no permit is needed, rise and run, landings, handrails and guards must still meet the Ontario Building Code. We check this on every interlock entrance. Read more in our permit guide.
Interlock or concrete?
| Interlock | Concrete | |
|---|---|---|
| Look | Landscaped, stone-like | Clean, monolithic |
| Repairs | Individual units can be lifted and reset | Patches or replacement |
| Movement | Flexes; needs a deep, well-drained base | Rigid; needs proper support and footings |
| Typical cost | Usually higher per step | Precast is usually lowest |
If a concrete entrance suits your house better, see concrete steps. If you love the interlock look but your concrete steps are sound, an interlock or natural-stone veneer over the existing steps may also be an option — ask at the site visit.
Pricing
New interlock steps run about $400–$1,300 per step in Ottawa. A premium or natural-stone coping upgrade adds about $150–$400 per step. Landings, removal of old steps and drainage work add to the total.