Formwork (shuttering) is measured as the area of concrete surface the forms touch, in square metres: slab soffits between beams, the two sides and the bottom of each beam below the slab, all four faces of each column, the vertical edges of footings and slabs, and the stair soffit, risers and sides. For the 12-column, 2-storey house used across this site's estimating series (built-up area 175.06 m2, about 1,884 sq ft), that comes to about 410.8 m2 of formwork, or 2.35 m2 for every m2 of built-up area. At Suryabinayak Municipality's 2081/82 rates the shuttering costs about Rs 3.67 lakh, roughly Rs 195 per sq ft of floor area.
This guide shows how to take off the area element by element, the measurement rules from IS 1200 Part 5, a one-room example you can check by hand, the full house table, how long the props must stay, and the mistakes that cause arguments between owners and shuttering contractors on Nepali sites.
Practise estimating questions: engineering MCQ practice.
What formwork, shuttering and centering mean on site
On Nepali sites the three words are used loosely. Shuttering is the face material that holds the wet concrete: plywood sheets, steel plates or planks. Centering is the support under it: steel props (jacks), bearers and runners, or local wood ballies on older sites. Formwork covers both. A contractor who quotes "shuttering per sq ft" normally means the face area plus all the support and labour, and that is also how the standard measures it.
The Indian standard for measuring formwork, IS 1200 Part 5, says the item includes all supports, struts, braces, wedges, mud sills, bolts, ties and clamps, plus working scaffolds, ladders and gangways. So you do not count props separately in a bill. You count the contact area only.
The measurement rules in short
| Rule (IS 1200 Part 5) | What it means on a house |
|---|---|
| Measure the actual surface in contact with concrete, in m2, to 0.01 m2 | Take the face of the form, not the plan area of the slab and not the concrete volume |
| No deduction for openings up to 0.4 m2 each | Small duct or pipe openings in a slab are not deducted; the stair opening (6.72 m2 in the example) is |
| Beam forms run up to the column faces; no deduction from column forms where beams meet them | Columns are taken full height from footing top to slab soffit |
| Secondary beams run up to the sides of main beams, with no deduction from the main beam | Measure each beam's clear length between supports |
| Slab edges and breaks under 203 mm deep go in running metres | A 125 mm slab edge is billed per metre, not per m2 |
| Stair: sloping soffits, risers and stringers measured; landings excluded | Landings are measured with the flat slab soffits |
Read the full clauses in the IS 1200 Part 5 text (law.resource.org). Your contract can change these rules, so read the item description in the BOQ before you measure.
Step-by-step method
- Collect the sizes from the structural drawing: footing size and edge depth, column size, column height from footing top to each slab soffit, beam width and depth (including the slab), slab thickness, clear spans and the stair layout.
- Footings: perimeter x vertical edge depth for each footing. For a sloped footing, the sloping top is often finished by hand with a stiff mix and not shuttered. If your engineer wants it shuttered, add the area of the four sloping faces.
- Columns: 4 x column width x height for a square column, measured full height from footing top to the slab soffit of each floor. Do not deduct where beams meet.
- Plinth beams: 2 sides x full depth x clear length. If the beam sits on a toe wall or a levelled PCC bed there is no soffit form.
- Floor and roof beams: (2 x depth below slab + width) x clear length between column faces.
- Slabs: gross slab area minus the plan area of beams and columns, minus openings over 0.4 m2 such as the stair hall. Add slab edges in running metres.
- Staircase: sloping waist soffit + risers + the side forms (both sides if walls go up after the frame). Landings go with the slab soffits or as their own line.
- Add the lines, then price each line at the rate for that element. Slab, beam and column forms have different rates because the support work is different.
Example 1: one room bay standing alone
Take one 4.0 m x 3.6 m bay (column centre to centre) of a single-storey room: 350 x 350 columns, 250 x 355 beams with a 125 mm slab, storey height 3.0 m from floor to slab top. These are example values; use your drawing.
| Item | Working | Area |
|---|---|---|
| Slab soffit | (4.0 - 0.25) x (3.6 - 0.25) = 3.75 x 3.35 | 12.56 m2 |
| Beams | clear lengths 2 x 3.65 + 2 x 3.25 = 13.80 m; (2 x 0.23 + 0.25) = 0.71 m per metre; 13.80 x 0.71 | 9.80 m2 |
| Columns | height to slab soffit 3.0 - 0.125 = 2.875 m; 4 x 0.35 x 2.875 = 4.03 m2 each; 4 columns | 16.10 m2 |
| Slab edge | 2 x (4.35 + 3.95) = 16.6 running m, 0.125 m high | 2.08 m2 |
| Total | 40.54 m2 |
So a room with a 12.56 m2 ceiling needs about 40.5 m2 of formwork, 3.2 times the ceiling area. That ratio can surprise owners who expect shuttering to equal the slab area. In a full house the ratio falls because neighbouring rooms share beams and columns. Priced at the Suryabinayak rates in the cost table below (slab 923.92, beam 1,311.65, column and edge 685.17 per m2) the room comes to about Rs 36,900.
Example 2: the whole 2-storey house
The same house as the whole-house cement and steel post: 12 columns on a 3 x 4 grid (bays 3.5 + 4.0 m one way, 3.0 + 3.6 + 4.2 m the other), 350 x 350 columns 6.95 m high from footing top, 250 x 355 beams, 125 mm slabs on two floors, slab edge 7.85 x 11.15 m, 1.5 x 1.5 m footings with a 0.2 m vertical edge, and a dog-legged stair in a 2.1 x 3.2 m hall. The beam clear length is 56.45 m per level, the same figure used in the RCC beam post.
- Footing edges: 12 x 4 x 1.5 x 0.2 = 14.40 m2. The sloping tops would add 2.30 m2 per footing (27.55 m2 for 12) if shuttered; they are left out here.
- Columns: 12 x 4 x 0.35 x 6.95 = 116.76 m2.
- Plinth beam sides: 56.45 x 2 x 0.355 = 40.08 m2 (no soffit; the beam sits on a toe wall).
- Floor and roof beams: 56.45 x 0.71 = 40.08 m2 per level, 80.16 m2 for two levels.
- Slab soffits: 87.53 - 14.11 (beams) - 1.47 (columns) = 71.95 m2 per floor; first floor minus the 6.72 m2 stair opening = 65.23; total 137.17 m2.
- Slab edges: 38.0 m per floor x 2 = 76.0 running m (9.50 m2 at 125 mm).
- Staircase: two flights of 9 risers (166.7 mm) and 8 treads (275 mm), 1.0 m wide, 150 mm waist. Sloping soffit 2 x 2.663 x 1.0 = 5.33 m2; risers 18 x 0.1667 x 1.0 = 3.00 m2; four side forms 2.33 m2; mid landing 2.1 x 1.0 = 2.10 m2. Total 12.76 m2. Stair sizes come from the staircase dimensions post.
| Element | Area (m2) | Share | Rate used (Rs/m2) | Amount (Rs) |
|---|---|---|---|---|
| Footing edges | 14.40 | 3.5% | 685.17 | 9,866 |
| Columns | 116.76 | 28.4% | 685.17 | 80,000 |
| Plinth beam sides | 40.08 | 9.8% | 685.17 | 27,461 |
| Floor and roof beams | 80.16 | 19.5% | 1,311.65 | 1,05,141 |
| Slab soffits | 137.17 | 33.4% | 923.92 | 1,26,734 |
| Slab edges | 9.50 | 2.3% | 685.17 | 6,509 |
| Staircase | 12.76 | 3.1% | 923.92 | 11,786 |
| Total | 410.82 | 100% | average 895 | about 3,67,500 |
Rates are from the Suryabinayak Municipality rate analysis 2081/82, section 12, including 15% overhead: column post 685.17, slab with steel prop and plywood 923.92, beam with steel prop and plywood 1,311.65 per m2. That list has no footing, edge or stair item, so the column rate is used here for the vertical side forms that need no props (footing edges, plinth beam sides, slab edges) and the slab rate for the stair. Those three choices are this example's assumptions. The same section also lists formwork using local wood at 260.21 per m2; read its analysis to see what it covers before you use it. Rates differ by municipality and year, so use the rate book of your own municipality or district.
Two numbers are worth keeping. The house needs about 2.35 m2 of formwork per m2 of built-up area (410.82 / 175.06), and about 7.8 m2 per m3 of structural concrete (410.82 / 52.63). Columns and beams together are almost 58% of the area, which is why a frame with many small columns costs more to shutter than its slab area suggests.
Quick ratios for a first check
| Element | Formwork per m3 of concrete | Why |
|---|---|---|
| 125 mm slab | 8.0 m2 | 1 / 0.125 (soffit only) |
| 150 mm slab | 6.7 m2 | 1 / 0.15 |
| 350 x 350 column | 11.4 m2 | 4 x 0.35 / (0.35 x 0.35) |
| 400 x 400 column | 10.0 m2 | 4 / 0.4 |
| 250 x 355 beam under 125 slab | 12.3 m2 | 0.71 / (0.25 x 0.23), below-slab part only |
| Whole frame of the example house | 7.8 m2 | 410.82 / 52.63 |
Use these ratios only to check a bill or an estimate. The final quantity must come from measuring each element, as above. The concrete volumes themselves are in the RCC slab, RCC column and isolated footing posts, and the concrete calculator gives m3 and bags for any member.
How much material is on site at one time
The total of 410.8 m2 is the billed area, not the plywood you need. Contractors cast one floor, wait, strip and move the same sheets up. For the example house, one floor lift is about 72 m2 of slab soffit, 40 m2 of beam forms and 4.75 m2 of edges, about 117 m2. An 8 x 4 ft sheet (2.44 x 1.22 m) covers 2.98 m2, so the slab soffit alone takes about 24 full sheets, or 27 once you allow about 10% for cut pieces. If the contractor also uses plywood for beam sides, a full set for one floor is roughly 40 to 45 sheets.
The props are the item that limits speed. The props under the ground floor roof must stay while the slab gains strength, so the next floor cannot borrow them early. The spacing of props depends on their capacity, the slab thickness and the bearers used; ask the engineer or the formwork contractor for their layout rather than copying a spacing from another site.
When forms and props can come out
IS 456:2000 clause 11.3 gives minimum periods for ordinary Portland cement where the air temperature does not fall below 15 degrees C and curing is adequate:
| Form or support | Minimum period | On the example house |
|---|---|---|
| Vertical forms to columns, walls, beam sides | 16 to 24 hours | Column and beam side forms |
| Slab soffit forms (props refixed at once) | 3 days | Ply can be struck, props put back |
| Beam soffit forms (props refixed at once) | 7 days | Beam bottoms |
| Props to slabs spanning up to 4.5 m | 7 days | All slab panels here (largest bay 4.2 m) |
| Props to slabs spanning over 4.5 m | 14 days | Not in this house |
| Props to beams and arches spanning up to 6 m | 14 days | All beams here |
| Props to beams and arches spanning over 6 m | 21 days | Not in this house |
The code says these periods must be suitably changed for other cements and lower temperatures. If your cement is PPC, or the weather is cold (winter mornings in Kathmandu and the hills often fall below 15 degrees C), expect the engineer to ask for longer periods. The rule behind the table is that forms stay until the concrete has at least twice the stress it will carry when the forms come off. Read IS 456:2000 clause 11.3, and follow your structural engineer and the NBC 205:2024 drawings and notes that your municipality approved.
Common mistakes seen on Nepali sites
- Paying on slab plan area when the contract says contact area. Some shuttering contracts are written per sq ft of roof (slab plan area). The example house has 175 m2 of slab plan but 410.8 m2 of contact area. Both ways are fine, but the rate must match the method. A per-sq-ft-of-roof rate should be about 2.3 times a per-m2-of-contact rate for the same money.
- Measuring beam sides full depth. Below a slab, only 230 mm of a 355 mm beam has side forms. Taking full depth adds 0.25 m2 per metre of beam, about 28 m2 on this house.
- Adding a soffit to a plinth beam on a toe wall. There is no bottom form, so pay for two sides only.
- Deducting column faces at beam junctions. IS 1200 does not deduct them. Some contracts do; agree on one rule.
- Forgetting slab edges, the stair and the parapet or chajja when comparing two quotations. A quote that leaves them out looks cheaper and can claim them later.
- Removing props early to reuse them on the next floor. Sagging slabs and cracked beam ends start here. Keep the periods above or longer.
- Loose or unoiled forms. Gaps leak cement slurry and leave honeycombing; bulging column forms waste concrete and need hacking before plaster. Check ties, joints and level before every pour.
Frequently asked questions
Is formwork measured in m2 or sq ft?
IS 1200 Part 5 measures it in m2 of contact area. Site contracts in Nepal often use sq ft. 1 m2 = 10.764 sq ft, so 410.8 m2 is about 4,422 sq ft.
Do I deduct openings from slab formwork?
Openings up to 0.4 m2 each are not deducted. Larger ones, such as a stair hall or a skylight, are deducted.
How much shuttering does a 1,000 sq ft house need?
For a frame like the example, roughly 2.3 to 2.4 sq ft of formwork per sq ft of floor, so about 2,300 to 2,400 sq ft. More columns, deeper beams or a cantilever will push it up. Measure from your drawings before you sign a contract.
Is the cost of props included in the shuttering rate?
Yes, in the standard method. Props, bearers, ties and staging are part of the formwork item and are not billed separately.
Where does formwork fit in the total house cost?
For the example house it is about Rs 3.67 lakh out of about Rs 23 lakh for the whole structure, roughly 16%. See the house construction cost page and the other free engineering tools for the rest of the estimate.
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