Two jobs close out in the same quarter. On the two-storey villa the formwork line is thirty percent over, an illustrative number but the kind of gap that gets a meeting. On the fourteen-storey tower the same line came in under, and the site team is quietly using the slack to cover a rebar overrun. Same estimator, same rate library, same subcontractor. Both were priced as though plywood were consumed like concrete, so the tower, which used its panels fourteen times, was charged for capital it never burned, and the villa, which used them twice, was charged for reuse it never got.
Formwork is not a material cost. It is capital equipment that you make up, use a number of times, and then write off — a rental you pay to yourself. The rate per square metre of contact area depends almost entirely on how many uses you achieve, and that number is a scheduling decision long before it is a materials decision.
The take-off looks like a material take-off: square metres of contact area written into a bill, and the brain reaches for a rate the way it does for plaster. But plaster is consumed once. The same panel can appear on the second floor, the fifth and the eleventh.
The code does not rescue you. The NSCP, and the ACI 318 concrete code it draws on, treat formwork as a safety matter: load-bearing forms and shoring stay until the member can carry its own weight and the loads placed on it. Non-load-bearing vertical forms carry no structural load and come off far earlier — column and wall forms, beam and slab side forms and stop ends are routinely stripped within a day — and reshoring is a recognised alternative to leaving the original shores standing. The removal criteria are set by the design professional in the contract documents, and the contractor is responsible for the formwork design and for meeting them. That is strength, not economics. No code states how many times a panel may be reused; reuse is governed by handling, workmanship, finish class and programme. The usual reference on forming practice is ACI 347R, the guide to formwork for concrete, which is guidance rather than a mandatory provision, and ACI 347.2R, the guide to shoring and reshoring, is the one that actually speaks to the cycle and multi-set argument below. Treat every reuse figure below as commercial practice, never as code.
The money is also spent in a lump at the start and consumed slowly across the programme, while the estimator fixes the rate at tender and the planner fixes the cycle after award. Neither owns the number that connects them.
Take one square metre of panel. It costs M pesos to make up, including making-up labour, is worth R pesos at the end, and achieves n uses. The capital to recover is (M - R), spread over n uses, so each use carries (M - R) ÷ n. Every use also carries its own labour, consumables and repair, whatever n is.
Cost per square metre of panel per use = (making-up cost - residual value) ÷ number of uses + per-use labour + per-use consumables + per-use repair allowance.
Only the first term contains n. The other three are flat, paid on the twentieth cycle exactly as on the second, so the capital term is the only part planning can move, and it collapses fast at low use counts and slowly at high ones: two uses to four halves it, twelve to fourteen barely touches it. That curve explains both the tower and the villa.
Panels wear out on handling, not on a calendar, and are retired when the face can no longer deliver the specified finish, usually well before the panel is structurally spent. But the uses you can book against a job are capped by the programme.
With conventional props and plywood decks, slab soffit forms cannot go up again until the floor below has gained enough strength to be struck under whatever criterion your engineer has set. If the forms must stand longer than one cycle, and on a seven-day cycle they usually must, one set cannot keep up and you need at least two in circulation. Two sets on a fourteen-floor building means seven uses each, not fourteen, however good the plywood is. That is a constraint of the system, not of physics: early-striking decks, drop-head props and flying tables are built to release the panel within one to three days while the props stay under the slab, which is often cheaper than buying a second set. Case C below is the price of not having that option, so price the system change before you price the second set.
As common practice, film-faced panels in careful hands are usually reported in the high teens to low twenties of uses for structural finishes, and plain plywood often in single figures, both falling away sharply once the face is broken. Those are ranges people quote, not values to price against: replace them with counts from your own completed jobs.
The building needs 850 m² of slab soffit form per floor over 14 floors. The panel set is 900 m² of film-faced plywood: 850 m² deployed plus 50 m² spare. Every peso figure and every percentage below is illustrative and must be replaced with your own cost and disposal records. Making up costs ₱1,250 per square metre of panel including plywood, bearers, joists and making-up labour; residual is 8 percent of making-up cost; erect and strip ₱185 per square metre per use; consumables ₱42; repair allowance ₱35.
Every figure above is an input, and every input carries an assumption. These are the ones that would move the answer if they turned out to be wrong, stated here rather than left buried in the arithmetic.
Two quantities are common to all three cases. Contact area = 850 × 14 = 11,900 m². Per-use stack = ₱185 + ₱42 + ₱35 = ₱262 per square metre per use, so per-use money over the job = 11,900 × ₱262 = ₱3,117,800. That never changes, because the contact area never changes.
By the formula, per square metre of panel: ₱1,150 ÷ 14 = ₱82.14, plus ₱262 = ₱344.14 per use. But you own 900 m² and form only 850 m² per floor, and the 50 m² spare carries 50 × ₱1,150 = ₱57,500 of capital that rate never recovers, which over the contact area is ₱57,500 ÷ 11,900 = ₱4.83 per square metre.
The set forms floors 1 to 8. By the end of floor 8, 350 m² is beyond repair and scrapped with no residual. A replacement 350 m² is made up and, with the 550 m² that survived, forms floors 9 to 14.
A reviewer could fairly object that giving the 550 m² now used fourteen times the same 8 percent is generous. Write that portion to zero and residual falls to 8% × ₱437,500 = ₱35,000, the total becomes ₱1,527,500 + ₱3,117,800 = ₱4,645,300, and the premium becomes ₱492,500, or 11.9 percent. Either convention is defensible; state which you used.
The cycle no longer lets one set keep up, so two full sets of 900 m² are made up and each achieves 7 uses.
Doubling the sets did not double the cost, and Case A shows why: capital was only 24.9 percent of the line, so doubling it adds a quarter, not a whole. The other ₱3,117,800 is per-use money bought by contact area, and the building still has 11,900 m² of soffit whether you own one set or two. Sets that have seen only seven uses are also in better condition at handover, so if they realise 15 percent instead of 8, residual becomes ₱337,500, the total falls to ₱5,030,300 and the premium to ₱877,500, or 21.1 percent.
Say the alternative is plain plywood at an illustrative ₱780 per square metre to make up, same residual percentage and same per-use stack, but far fewer uses. Film-faced costs (0.92 × 1,250) ÷ n(film) + 262; plain costs (0.92 × 780) ÷ n(plain) + 262. The per-use terms cancel, and so does the 0.92, leaving 1,250 ÷ n(film) = 780 ÷ n(plain), so n(film) ≥ n(plain) × 1,250 ÷ 780 = n(plain) × 1.6026.
Film-faced must earn at least 1.6026 times as many uses as plain just to draw level. Do not round that multiplier down to 1.60: it is the hurdle the dearer panel has to clear, so shaving it flatters film-faced and biases the buy decision. Carry 1.6026, or round up to 1.61. At an illustrative 6 uses for plain plywood, n(film) = 6 × 1,250 ÷ 780 = 9.62 uses, so in practice you need 10. Numerical check: plain = (0.92 × ₱780) ÷ 6 = ₱717.60 ÷ 6 = ₱119.60; film = ₱1,150 ÷ 9.6154 = ₱119.60. Both give ₱119.60 + ₱262 = ₱381.60. Level, as required. The spare-panel factor of 900 ÷ 850 sits on both capital terms, so it cancels too.
What does move the answer is a per-use cost that differs. If plain plywood carries a repair allowance of an illustrative ₱55 rather than ₱35, its rate at 6 uses becomes ₱119.60 + ₱185 + ₱42 + ₱55 = ₱401.60, and film-faced matches it when ₱1,150 ÷ n = ₱401.60 - ₱262 = ₱139.60, giving n = 8.24 uses. One line of the stack moved the break-even by nearly a use and a half.
This is the practical payoff of showing the derivation. If the tender assumed one set at 14 uses and the post-award sequence forces two sets at 7 uses each, the exposure is not a matter of opinion: ₱1,035,000 on a line priced at ₱4,152,800, every input traceable to a stated assumption. An estimator carrying a single blended rate cannot demonstrate that, and usually absorbs it. If you keep this kind of build-up in a spreadsheet re-cut for every bid, the RHCES Estimator is laid out the same way, with capital, use count and per-use lines kept apart, so the reuse assumption stays visible instead of vanishing into a single number.
No. The NSCP and ACI 318 address when load-bearing forms and shoring may safely be removed, leave the removal criteria to the design professional in the contract documents, and leave the formwork design and its execution to the contractor. That is a strength and stability matter. Reuse counts are commercial and workmanship territory, informed by guidance such as ACI 347R, by ACI 347.2R where shoring and reshoring drive the cycle, and by the finish class specified. If someone hands you a use count and calls it a code figure, ask which document it came from.
Yes, because that lump rate was built on an assumed number of uses whether or not anyone wrote it down. If the sequence changes, the subcontractor will produce a claim built on exactly this arithmetic, and you want to have run it first. Ask for the quotation split into capital, uses and per-use components before award.
The same equation applies, but with a much larger capital term and a much higher use count, so capital per use gets small and the answer becomes dominated by per-use labour and consumables. That is why system formwork wins on tall repetitive buildings and loses badly on a single villa. Run both options through the same build-up with your own figures rather than accepting a supplier comparison built on someone else's use count.