Why does the page ask whether the wall needs designing?

Because above a certain retained height — and lower than most people expect where there is a surcharge behind it, such as a drive or a building — a retaining wall stops being a landscaping job and becomes an engineered structure. That is not ours to decide, so the page states the threshold and what it depends on, and stops there.

Is the land drain at the foot of the wall counted?

No, and the reason is on its row: where a drain discharges is a decision about the levels of the site rather than about the wall. The gravel behind the wall is counted, because it follows from the wall's own dimensions.

Why is there no cap course in the figures?

A cap is a second block size along the same run, and nothing here counts it. It is a deliberate gap rather than an oversight — add it as a line of its own from the block calculator once you have chosen the cap.

Does the footing figure include the excavation?

It gives the concrete for the footing at the size the height calls for. What comes out of the ground to make room for it, and where it goes, depends on the site and on what you can get a machine to.

Plan a retaining wall

Every trade, one set of measurements

Retaining wall planner

A retaining wall is a run that holds back ground, and everything about it follows from how much ground and how high. From a length and a height come the blocks or the poured stem, the footing under it, the drainage gravel and the geogrid layers — and, before any of that, the one question this page asks that none of the others do: whether a wall this size is still something you may build without a design.

Timber-framed house under construction with ladders, sawhorses and lumber

New wallNot drawn yet

1 Measure the wall
2 Choose its finishes
3 Save it to My Project

Give the wall a length and a retained height, and it is drawn here with every figure beside it.

The wall

Nothing here is required. Each figure appears as soon as it has what it needs.

Length and height, and the height is the figure that matters most: it decides the footing, the reinforcement and whether the wall is within what a code allows to be built without an engineer's design.

Add a retaining wall

A line and a height, like a fence — and two walls that are not variants of each other worked out side by side: dry-stacked blocks with geogrid, or a poured stem on a footing. The drainage behind both is a row of its own, because it is the load most retaining walls actually fail under.

LengthftRetained heightft

Everything the wall needs

In the order the work is done. No row has a figure yet.

Nothing in this wall is everything the wall needs yet. Choose how a surface is finished, or what else is being done, and its rows appear here.

Assumptions assumed

Everything the figures above rest on that you did not give, and what they are still waiting for.

Nothing is assumed yet: give the wall its measurements to begin.

How the planner runs

Give the wall its length and the height of ground it retains.
Read the stability check first — it is the row that decides whether the rest of the page applies to your wall at all.
Choose blocks or a poured stem; each carries its own footing and its own reinforcement.
Take the drainage gravel and the geogrid layers the height calls for.
Save it into your project, and keep the check's answer with it.

Where the figures come from

Reading for the decisions

Questions

Why does the page ask whether the wall needs designing?: Because above a certain retained height — and lower than most people expect where there is a surcharge behind it, such as a drive or a building — a retaining wall stops being a landscaping job and becomes an engineered structure. That is not ours to decide, so the page states the threshold and what it depends on, and stops there.
Is the land drain at the foot of the wall counted?: No, and the reason is on its row: where a drain discharges is a decision about the levels of the site rather than about the wall. The gravel behind the wall is counted, because it follows from the wall's own dimensions.
Why is there no cap course in the figures?: A cap is a second block size along the same run, and nothing here counts it. It is a deliberate gap rather than an oversight — add it as a line of its own from the block calculator once you have chosen the cap.
Does the footing figure include the excavation?: It gives the concrete for the footing at the size the height calls for. What comes out of the ground to make room for it, and where it goes, depends on the site and on what you can get a machine to.

When the work is a job rather than a room. Plenty of it never starts from a space — a slab, a roof, a deck, a panel upgrade. Each of those is a job takeoff: give it the few figures that job is described by, and every trade in it comes back together, the way the room does here.