Floor Slabs and Safety

On 5 June 2026, Indonesia's Minister of Public Works said average progress across 93 Sekolah Rakyat school sites was close to 70 percent, with completion targeted for 27 June 2026. Sites were pushing an average of 1 to 2 percent a day, and up to 3 percent at sites that had fallen behind, while the government offered help from the armed forces at sites short of workers (Meilina, 2026). On 13 May 2026, the ministry had described method changes to speed up construction, including structural steel, metal deck with wire mesh, and hollow core floor slabs (ANTARA, 2026).

The choice of floor slab method is usually made on time, cost and equipment availability. The same choice also decides who works at height, for how long, and what can collapse. This article compares the three methods from a worker safety point of view.

How We Compare

We use three criteria: exposure to work at height, the risk of temporary works or not-yet-stable elements collapsing, and lifting operations. The criteria rest on two regulations. Minister of Manpower Regulation No. 9 of 2016 on occupational safety and health in work at height requires employers to ensure that work at height is done only when it cannot be done at ground level. It names parapet walls or guardrails as the means of preventing falls from permanent work floors, and personal fall arrest equipment for temporary work floors, meaning surfaces used for a short time or that may collapse (Kementerian Ketenagakerjaan Republik Indonesia [Kemnaker], 2016). Minister of Public Works and Housing Regulation No. 10 of 2021 on construction safety management system guidelines classes lifting, work at height above 1.80 metres and work on scaffolding as special work that requires a construction safety analysis (AKK) (Kementerian Pekerjaan Umum dan Perumahan Rakyat [Kementerian PUPR], 2021).

Conventional Formwork

The slab is cast on timber or plywood formwork supported by shoring scaffolds, as in the cover photo. This method puts many tradespeople on temporary work floors for a long time, from building the formwork and fixing reinforcement to pouring and stripping. A qualitative study on a hotel building project in Manado identified formwork stripping hazards including nail punctures, tripping over leftover material, slipping, trapped hands, being struck by formwork material and falls from height, with risk levels from low to high (Fiorela et al., 2025). During the pour, the weight of wet concrete is carried by the shoring, so shoring stability becomes a critical point that falls within the scope of the AKK (Kementerian PUPR, 2021). On the plus side, the method is familiar to local crews and needs no large lifting equipment.

Metal Deck

Steel deck sheets are laid on steel beams, fitted with reinforcement or wire mesh and then cast. The deck acts as the mould, so less formwork and propping is needed under the slab. The risk moves to edges and openings. Workers walk on beams and on sheets not yet fixed, at floor edges without guardrails and around openings for stairs or services. Until the sheets are fully fixed, the surface is a temporary work floor that calls for personal fall arrest, and once it becomes a permanent work floor, edge guardrails are needed (Kemnaker, 2016). Bundles of sheets lifted by crane also add to the lifting workload.

Hollow Core Slabs

Precast hollow core planks are made in a factory, transported, then lifted by crane and set on the beams. The number of workers under the slab and the need for shoring both fall sharply, but each plank is a heavy lift placed at the edge of an unfinished floor. An analysis of 125 OSHA-investigated accidents in US modular and prefabricated construction found 48 deaths, or 38.4 percent. Falls were the most common cause and unstable structures the most frequent underlying cause. The researchers called for attention to stabilising elements during lifting, storage and installation, and to fall protection during assembly at height (Fard et al., 2017).

Which to Choose

In our view, no slab method is safe in itself. Conventional formwork spreads risk across many workers for a long time. Metal deck concentrates risk at edges and openings during installation. Hollow core slabs shift risk to lifting and element stability, with fewer workers exposed but more serious consequences when something fails. Under schedule pressure we see two traps: switching methods without updating the AKK and the crews' competence, and running several methods at once on one site so that lifts pass over other crews.

Practical steps for all three:

• Fix the slab method before mobilisation and write the AKK for the method actually used (Kementerian PUPR, 2021).
• Formwork: inspect shoring before each pour, set a stripping sequence, and clear nails and leftover material every day (Fiorela et al., 2025).
• Metal deck: install edge guardrails and opening covers before anyone works on the deck (Kemnaker, 2016), and fix any sheets taken out of their bundle before the day's work ends.
• Hollow core: prepare a lift plan for each plank type, set exclusion zones under the load path, and provide anchor points for installers working at the edge (Fard et al., 2017).

The limits of the evidence should be stated. The data of Fard et al. (2017) come from US investigation reports, the study by Fiorela et al. (2025) is a qualitative study of one project, and we have not found Indonesian data comparing accident rates by slab method.

How Nusa Safety Helps

Nusa Safety helps project teams prepare the AKK for slab work through the risk assessment and JSA workshop, prepares workers at height through working at height training and operators and riggers through lifting operator and rigger training, with certification run together with licensed PJK3 partners, and checks how controls are applied on site through the HSE and CSMS audit.

This article is general information, not legal or professional advice for any specific case.

References

1. ANTARA. (2026, May 13). PU percepat pembangunan Sekolah Rakyat Tahap II di berbagai daerah [Public Works Ministry accelerates Sekolah Rakyat Phase II construction across regions]. ANTARA. https://www.antaranews.com/berita/5565807/pu-percepat-pembangunan-sekolah-rakyat-tahap-ii-di-berbagai-daerah
2. Fard, M. M., Terouhid, S. A., Kibert, C. J., & Hakim, H. (2017). Safety concerns related to modular/prefabricated building construction. International Journal of Injury Control and Safety Promotion, 24(1), 10-23. https://doi.org/10.1080/17457300.2015.1047865
3. Fiorela, L., Maddusa, S. S., & Rahman, A. (2025). Manajemen risiko K3 menggunakan metode Job Safety Analysis pada pekerjaan pembongkaran bekisting di proyek pembangunan gedung Hotel X Manado [OHS risk management using job safety analysis in formwork stripping on the Hotel X building project in Manado]. Jurnal Kesehatan Tambusai, 6(2), 8390-8400. https://doi.org/10.31004/jkt.v6i2.45693
4. Kementerian Ketenagakerjaan Republik Indonesia. (2016). Peraturan Menteri Ketenagakerjaan Nomor 9 Tahun 2016 tentang Keselamatan dan Kesehatan Kerja dalam Pekerjaan pada Ketinggian [Minister of Manpower Regulation No. 9 of 2016 on occupational safety and health in work at height]. https://pasal.id/peraturan/permen/permenaker-no-9-tahun-2016
5. Kementerian Pekerjaan Umum dan Perumahan Rakyat. (2021). Peraturan Menteri Pekerjaan Umum dan Perumahan Rakyat Nomor 10 Tahun 2021 tentang Pedoman Sistem Manajemen Keselamatan Konstruksi [Minister of Public Works and Housing Regulation No. 10 of 2021 on construction safety management system guidelines]. https://pasal.id/peraturan/permen/permen-pupr-no-10-tahun-2021
6. Meilina, K. (2026, June 5). Pemerintah kebut pembangunan 93 Sekolah Rakyat, target rampung akhir Juni 2026 [Government races to build 93 Sekolah Rakyat schools, completion targeted for end of June 2026]. Katadata. https://katadata.co.id/finansial/bursa/6a22c0c00580c/pemerintah-kebut-pembangunan-93-sekolah-rakyat-target-rampung-akhir-juni-2026