What Should a Retaining Wall Quote Include?

Two quotes, four thousand dollars apart, same wall. That happens constantly, and the gap is almost never profit margin. It is drainage, base depth, and whether the cheaper bid intends to do either.

You cannot see any of it once the wall is finished. That is the whole problem with buying this particular service.

The line items that should be there

Excavation and disposal. How deep, and where the spoil goes. A wall needs its base trench cut into firm subgrade, below the topsoil and organic material. If a quote does not say how deep, nobody has committed to anything.

Granular base. Material type, depth, and compaction in lifts. This is the single most important line on the page. A wall is only as good as what sits under the first course, and compacting in thin layers takes time that shows up in labour.

Drainage. Weeping tile, clear stone behind the wall, and, this part matters, where the water exits. Plenty of quotes list drain rock and never say where the water goes. A drain that terminates into clay is decoration.

Geotextile. The fabric separating your clear stone from the native soil. Skip it and the clay migrates into the drainage stone over a few seasons and quietly plugs it.

Block, stone or timber. Named product and colour, plus the cap detail. “Concrete block” is not a spec.

Geogrid, where the height requires it. Layers, spacing and length back into the fill.

Backfill and compaction. Again in lifts, again taking time.

Restoration. The sod, the beds and the driveway edge that the equipment crossed to get there.

Permits. Who applies, and whether the fee is in the price or extra.

Why pricing is quoted per square face foot

Face area means the exposed front of the wall, height multiplied by length, ignoring the buried base. It is the standard unit in this trade because it tracks the material and the labour reasonably well.

Installed ranges across our materials run roughly: timber $50 to $100 per square face foot, modular concrete block $80 to $150 with base preparation and drainage included, boulder $100 to $250, and natural stone $150 to $300 because every piece gets fitted individually. Broader landscape budgeting sits on our Calgary landscaping costs page, and the material breakdown lives on the retaining walls service page.

Multiply your own measurements by those ranges before you read anyone’s quote. If a bid sits well under the bottom of the range, something has been left out, and now you know which lines to go looking for.

Height changes the paperwork, and the price

Calgary measures the exposed face from finished grade at the front. Under 1.2 metres, no development permit is needed. From 1.2 to 1.5 metres, a development permit. Above 1.5 metres, a development permit and engineered drawings from a licensed engineer.

Permit processing takes two to four weeks. A quote that promises a start date sooner than that on a wall which clearly triggers a permit has either not read the bylaw or is planning to skip it. Both are your problem later, because unpermitted structural work complicates a sale.

On sloped lots there is often a design route around the engineering threshold. Two shorter walls with a planting bench between them, where the upper wall does not structurally load the lower one. Whether that works depends on the grade and it is worth asking about before you accept a single tall wall as the only option.

Questions that separate the bids

How deep is the base going, and what are you compacting it with? Where does the drainage exit? Are you installing geogrid, and at what spacing? Who pulls the permit? What does the workmanship warranty cover, and when does it start?

Ask those five and the quotes stop looking similar very quickly.

The warranty question catches people out. Ours starts at handover, after we walk the finished build with the property owner. A warranty that starts at invoice date and runs a year is a different product from one that starts when the work is signed off.

The bid that is too low

Sometimes it is a smaller crew with lower overhead, and that is fine. More often it is a wall with 150 millimetres of base instead of 300, no fabric, and drain rock with nowhere to drain to. It will look identical at handover.

It will not look identical in four winters. Calgary’s freeze-thaw cycle finds every shortcut, and it finds them in a specific order: the drainage first, then the base, then the face.

We have rebuilt enough of these to recognise the pattern before the excavator starts. The tell is usually a wall that is straight for most of its run and bulging in exactly the spot where water collects.

Getting quotes worth comparing

Give every contractor the same information. Height at the tallest point, total length, what the wall is holding back, and whether machinery can reach the site. Access is a real cost driver, and a quote written without seeing the approach is a guess.

Photographs help. So does saying plainly what the wall is for, because a garden bed edge and a wall supporting a driveway are different structures even at the same height.

We have been building walls across Calgary and the surrounding communities since 1990, and we are ICPI certified, which is mostly relevant to the base and drainage detail that decides how these builds age. Estimates are free, and we will itemise them. Send through your measurements and we will put real numbers against them.

A worked example

Take a wall 12 metres long and 1.2 metres of exposed face. That is roughly 155 square face feet.

In modular block at $80 to $150 per square face foot installed, the range lands between about $12,400 and $23,250, with base preparation, drainage stone, geotextile and cap included. In timber at $50 to $100 it runs lower, though the replacement cycle is shorter. In natural stone at $150 to $300 it runs well above.

Now change one thing. Raise the wall to 1.6 metres and the face area grows to roughly 207 square feet, the build crosses the engineering threshold, and you have added drawings, a permit and a geogrid reinforcement plan that requires excavating further back into the slope. The cost does not scale with the height. It steps.

That step is why it is worth measuring properly before you assume a budget, and why a quote that does not state the height it priced is difficult to rely on.

Frequently Asked Questions

Why are retaining wall quotes so different from each other?

Because the expensive parts are invisible. Base depth, drainage, geotextile and geogrid are where the money and the time go, and a quote can omit all four while still describing the same finished wall. Comparing totals without comparing those lines tells you very little.

What is a square face foot?

The exposed front area of the wall, height multiplied by length, ignoring the buried base. It is the standard pricing unit in this trade because it tracks material and labour reasonably well across different wall heights.

Should the quote include the permit fee?

It should at least say who applies and whether the fee is included or billed separately. Calgary requires a development permit above 1.2 metres of exposed face and engineered drawings above 1.5 metres, with two to four weeks of processing.

How long should a retaining wall last?

A properly executed modular block build runs 25 to 50 years. Natural stone runs 50 to 100. Those figures assume the base and drainage were built to spec, which is the whole argument for reading the parts of the quote nobody sees afterwards.

If you only take one thing from this: ask where the water goes. The answer tells you more about a contractor than the price does.