GUIDE 13 · SHORING & SUPPORT SPANS

Formwork Support Spacing & Shoring Calculations: Safe Beam Spans Without Deflection

Author: İdris YAĞMAHAN / Mimar (Architect) Published: 01/03/2026 Read Time: 9 minutes Category: Shoring & Statics

Formwork Shoring System and H20 Beam Support Spans

Quick Technical Specification

Verified Engineering Specs

Referans Levha 18 mm SerPlywood Polymer Board 1250 × 2500 mm

Hedef Sehim Limiti f ≤ L / 400 DIN EN 13670 Fair-Faced Quality

15–20 cm Döşeme Aksı Secondary H20 Girder Spacing: 28 – 30 cm on-center

25–30 cm Döşeme Aksı Secondary H20 Girder Spacing: 22 – 25 cm on-center

35+ cm Ağır Döşeme Secondary H20 Girder Spacing: 20 cm on-center

Maks. Beton Basıncı DIN 18218: 60 kN/m² Lateral Pressure Waler Spacing 20-25 cm

1. Structural Support Principles for Polymer Formwork
2. Recommended H20 Girder Spacing per Slab Depth
3. Lateral Pressure on Walls: DIN 18218 Compliance
4. Common Jobsite Falsework Shoring Errors

1. Structural Support Principles

With wet concrete weighing 25 kN/m³, supporting falsework spacing cannot be generalized. Spans must be calibrated against slab thickness to restrict flexure to L/400.

2. H20 Girder Spacing Guidelines (18mm Polymer)

15 cm Slabs: 30 cm girder spacing
20 cm Slabs: 28 cm girder spacing
25 cm Slabs: 25 cm girder spacing
30 cm Slabs: 22 cm girder spacing
35 cm Slabs: 20 cm girder spacing

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Frequently Asked Questions about Support Spans

Frequently Asked Questions

Common questions regarding board selection, reuse cycles, technical parameters, and global delivery.

What do hollow, honeycomb, and solid core describe?

They describe the internal cross-sectional geometry of the board. Honeycomb and cellular structures provide lightweight handling, while solid core boards offer different deflection and impact dynamics.

Is SerPlywood a manufacturer brand or a supply/trading brand?

The operating model is specialized polymer formwork procurement, supply, and direct project delivery. Manufacturing and authorized distribution credentials are fully specified within institutional documentation.

Can an 18 mm board be used in all formwork types?

Thickness alone does not determine full suitability. Polymer structure, fresh concrete hydrostatic pressure, support joist spacing, and framing connections must be evaluated within a proper formwork design.

What should the support joist spacing be?

There is no single support spacing applicable to all polymer boards. It must be determined from the manufacturer load-deflection tables and permissible deflection limits (e.g. L/500) for the specific concrete slab thickness.

How does the board behave in hot and cold weather?

Thermopolymers expand in heat and gain rigidity in severe cold. Therefore, an expansion joint gap (1.5 – 2 mm) recommended by the manufacturer should be maintained at board joints.

Can plastic formwork boards be cut on site?

Yes, they can be easily cut using standard circular saws or hand woodworking tools. Using a blade with appropriate teeth ensures clean, burr-free edges.

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