For a typical project of 10 m (33 ft) long, 600 mm (23.6 in) exposed height (all of Quebec): $12,277 doing it yourself, $11,000 to $17,000 by a contractor, before tax.
Materials at retail prices, rentals, delivery and disposal, plus your time as a beginner (*).
* Includes your time: 122 h × $35.05/h (beginner). Money spent only: $8,001
Tools to buy, on top: $197
Labour, equipment, materials, overhead and margin.
Crew pace: 35 person-hours
Stacked extremes (everything low, everything high): $7,428 to $26,782
The range shows the effect of documented price and productivity spreads. It is not a probability.
At $35/h: doing it yourself still costs less.
Break-even = (the contractor's typical price minus the money spent doing it yourself) divided by your person-hours. Before tax on both sides: GST and QST apply to both.
| Measure | Beginner | Intermediate |
|---|---|---|
| Money spent | $8,001 | $8,001 |
| Person-hours | 122 h | 84 h |
| Days of 8 h, 2 people | 8 days | 5.5 days |
| Your time at $35/h | $4,276 | $2,939 |
| True cost | $12,277 | $10,939 |
Working days only: add rain days and waiting times (curing, deliveries).
Before tax, one scale for every bar.
| Money, do it yourself | $8,001 |
|---|---|
| True cost, beginner | $12,277 |
| True cost, intermediate | $10,939 |
| Contractor | $11,000 to $17,000 ($14,000) |
| Materials | 35% | $4,953 |
|---|---|---|
| Labour | 10% | $1,347 |
| Equipment and rentals | 8% | $1,119 |
| Delivery and disposal | 10% | $1,438 |
| Overhead | 27% | $3,796 |
| Margin | 10% | $1,406 |
The range shows the effect of documented price and productivity spreads. It is not a probability.
Intermediate
Hours for the typical project: the work calculation (a crew's pace times the level's factor, with rework, learning and unloading) plus the guide's planning and checks.
A bed-edge garden wall and a wall that holds back a slope are not the same structure. Before anything else, note the visible height, what will sit above the wall and the soil behind it.
Wall rules come from your municipality, and in Montreal from your borough. A few examples: Laval requires a certificate of authorization to add or modify a retaining wall, and plans signed and sealed by an engineer from 1.8 m. Gatineau requires a certificate and, at 1.8 m and more measured from the low side, a design approved by an engineer and a guard. Quebec City limits walls to 1 m in front yards and 2 m in side and rear yards unless an engineer seals the plan. Terrebonne treats any wall of 1 m or more as a retaining wall and asks for an engineer's attestation and a surveyor's survey. How height is measured differs between cities: ask.
From front to back, the trench holds 150 mm of clearance in front of the block, the block depth, then 300 mm of clear stone for drainage. Its depth equals the pad thickness plus the buried course or courses. The calculator gives the width, depth and volume for your wall. If the wall is cut into a slope, the back must also be cleared over the full height.
The pad is the wall's foundation: MG-20 compacted to at least 150 mm, dead level. Geotextile lines the bottom and back of the trench so the soil cannot clog the drainage stone; it gets folded over the stone at the end.
The wall goes up course by course, and the drainage goes up with it: each course gets clear stone in its cores and behind, then compacted backfill behind the drainage zone. The perforated drain sits on the pad behind the first course and must exit to daylight or to the storm system where allowed. If an engineer designed the wall with geogrid, follow the plan exactly: the calculator's geogrid quantities are for budgeting only.
Height alone does not decide whether an engineer is required. According to the Ordre des ingénieurs du Québec, a retaining wall falls under the Engineers Act when its design needs a study of materials, depending on its function, height, soil, erosion or slide risk and loads. Municipal thresholds do not replace the Act.
Ordre des ingénieurs du QuébecChecked October 10, 2026
The RBQ says low walls and landscaping on private land need no licence. For a wall that holds up a driveway, a slope or a building, we recommend hiring a licensed business (subcategory 2.7) and an engineer: the RBQ does not define a height.
Régie du bâtiment du QuébecChecked October 10, 2026
Laval: certificate of authorization to add or modify a retaining wall, with a land surveyor's certificate of location; at 1.8 m and more, a cross-section signed and sealed by an engineer and a supervision mandate. About 30 days.
Ville de LavalChecked October 10, 2026
Gatineau: certificate of authorization for a retaining wall (certificate of location and scaled site plan); certificate for a decorative wall over 1.5 m; at 1.8 m and more, measured from the low side, design approved by an OIQ engineer and a guard at least 1,070 mm high.
Ville de GatineauVille de GatineauChecked October 10, 2026
Quebec City: maximum height of 1 m in front yards and 2 m in side and rear yards, unless an engineer's sealed plan is filed with a certificate application; at least 1 m between two walls (0.5 m in front yards); at least 0.5 m from the front lot line and 1.5 m from a fire hydrant; list of allowed materials since 2021.
Ville de QuébecVille de QuébecChecked October 10, 2026
Terrebonne: a wall of 1 m or more is a retaining wall for zoning purposes. The certificate requires an OIQ engineer's attestation of stability and safety and a surveyor's topographic survey; in a landslide zone, a geotechnical study.
Ville de TerrebonneChecked October 10, 2026
Saint-Jérôme: free permit for every retaining wall; engineer's attestation above 1.5 m.
Ville de Saint-JérômeChecked October 10, 2026
Before you dig, file a free request with Info-Excavation. The RBQ asks contractors to file at least 4 business days before the work; it is valid until its end date, 180 days at most.
Régie du bâtiment du QuébecChecked October 10, 2026
Thickness of compacted stone, width and burial depth of the first course, in numbers.
Clear stone behind the blocks, a perforated drain and an outlet to daylight. A wall that holds water ends up moving.
Beyond the maker's or the municipality's limits, or with a load above (driveway, slope), an engineer's design is required.
For taller walls, geogrid ties the wall into the soil. Its length and layers come from a design, not a habit.
Glued with an exterior concrete adhesive. For steps, every rise is the same.
The number of years and what is covered: bulging, settling, displaced blocks.
In every case: an RBQ licence when the work requires one, a business number (NEQ), civil liability insurance and a written contract.
Guide: choosing a contractorDraft: this content has not yet been reviewed by an installer or an engineer. The numbers come from the engine; the explanations may still change.