Ties once, everything else twice
A form for a free-standing wall is two faces held apart at a fixed distance and stopped from being pushed apart by the concrete. The sheathing, the studs behind it and the wales behind those all exist on both faces, so every one of them doubles the moment you form both sides. The ties do not, because one tie runs through the wall from one wale to the other. That single asymmetry is where most tie orders go wrong, and doubling the tie count on a large wall is an expensive error in the direction nobody notices until the invoice.
The tie count itself is a grid, not a rate. Rows come from the wale spacing divided into the height, ties per row come from the tie spacing divided into the length, and the total is the product. Both of those spacings arrive from the form design rather than from the wall, which is why they are inputs and why this page will not offer you a default that means anything.
Why the spacings are not on this page
Stud spacing, wale spacing and tie spacing exist to resist a lateral pressure, and that pressure depends on how fast you pour, how warm the concrete is, its unit weight and what is in the mix. A form grid that is comfortable at two feet an hour on a cold morning is a different grid at eight feet an hour in July. There is no spacing that is right for a wall in the abstract, only a spacing that is right for a wall poured a particular way — which is why the manufacturer publishes their systems against a pressure rating rather than against a wall height, and why the design belongs to somebody who knows what the pour plan is.
This page takes the grid you were given and counts the pieces in it. If you want to see how the pressure moves when the pour plan changes, that is the form pressure calculator, which does the same thing there: every coefficient is yours.
Panels against job-built
| Modular panels | Job-built | |
|---|---|---|
| Counted as | Panels per row, rows up the wall | Square feet of contact area divided by a sheet |
| The awkward part | The filler where the wall length does not divide by the panel width | Every corner, opening and top course is a cut |
| Reuse | Many pours if handled and cleaned | A few pours before the face goes |
| Where the money goes | Rental time and ties | Sheathing, lumber and the labour to build it |
The filler line is worth looking at before ordering. A 32 foot wall in 24 inch panels comes out at exactly 16 panels a row with nothing left over, which is the neat case. Move the wall to 33 feet and you have 16 full panels and a 12 inch gap per row per face, and that gap has to be closed by something — a narrow filler panel, a made-up piece of sheathing, or a change to where the wall starts.
The stud count is one more than the spaces
Studs at 12 inches on centre across a 32 foot wall is 32 spaces and 33 studs, because there is a stud at each end of every space and the ends are shared. The same plus-one applies to any centre-to-centre layout and it is the same arithmetic that catches people on a rebar mat. Miss it once per face and you are two studs short before you have started.
Wale rows work the other way. A row occupies a band of the wall rather than a line, so the count is the height divided by the spacing and rounded up: 96 inches at 24 inch spacing gives four rows, and the top row sits below the top of the pour rather than on it.
What is deliberately not here
No tie capacity, no allowable pressure, no verdict on whether the grid you entered suits the pour you are planning. Formwork is an engineered temporary structure and the consequences of getting it wrong are not gradual: a form that lets go during a pour releases the whole head of wet concrete at once, and people have died under collapsed forms and shoring. The design, the pre-pour inspection and the decision to strip belong to the engineer of record and to a competent person on site.
Two hazards worth naming rather than managing. Wet concrete is strongly alkaline and burns skin chemically, and the burn develops over hours, so someone kneeling in it does not feel the injury happening. And a form tie that is stressed and then released is a piece of steel under load, which is a different problem from the concrete entirely.
Questions people ask
Do I count ties once or twice on a two-sided form?
Once. A tie passes through the sheathing on both faces and is anchored against the wale on each side, so one tie serves both. The sheathing, studs and wales are the items that double when you form both faces. This is the most common error in a form take-off, and it doubles the item that is usually consumed by the pour and cannot be returned.
What stud and wale spacing should I use?
Whatever the form design for this pour says, and this page supplies none. Those spacings resist a lateral pressure, and the pressure depends on the placement rate, the temperature, the unit weight of the concrete and what is in the mix, not on the height of the wall. The manufacturer rates their system against a pressure figure, and matching a pressure to a grid is a design step done by the engineer of record or a qualified form designer.
How many sheets of plywood does a wall form take?
Form contact area divided by the sheet area, plus a waste allowance for cuts. A 32 by 8 foot wall formed on both faces is 512 square feet of contact area, which is 16 sheets at 32 square feet each before waste and 18 at a ten percent allowance. The waste figure earns its keep at corners, openings and the top course, where almost every sheet gets cut.
Why does the calculator ask for hardware pieces per tie?
Because systems differ and there is no universal answer. A snap tie with a wedge at each face takes two pieces; a taper tie with a nut and washer arrangement takes a different count; some panel systems clamp at the joint rather than at the tie. Enter what your system takes and the page multiplies. It does not know which system you have and does not guess.
Does this tell me whether my formwork will hold?
No, and it is not able to. It counts the pieces in a grid you supplied. Whether that grid resists the pressure your pour produces is a structural question involving the tie capacity, the sheathing span, the wale section, the bracing and the ground the whole thing stands on. Formwork failure is sudden and has killed people. That assessment belongs to the engineer of record and a competent person on site.