We specialise in formwork estimating
– Slab Soffits
– Slab Edgeboard
– Formwork Beams
– Formwork Columns
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DOWNLOAD an Example Formwork Estimate in Excel
Send your plans for quoting to Email: admin@speedyestimating.com.au
Ph: 0407 763 976 or Send a SMS message
Formwork Estimating
Formwork Estimating for Suspended Concrete Slabs
Estimating formwork for suspended concrete slabs is a critical aspect of construction planning. Accurate estimation ensures cost efficiency, timely project completion, and structural integrity. Here’s a comprehensive guide to understanding and estimating formwork for suspended slabs.
Understanding Formwork
Formwork is a temporary or permanent mold into which concrete is poured to achieve the desired shape. For suspended slabs, formwork must support the weight of the wet concrete, the reinforcement, and any additional loads until the concrete gains sufficient strength.
Key Components of Formwork for Suspended Slabs
- Shuttering: The panels or boards that form the mold.
- Supports: Props, scaffolding, or shoring that hold the shuttering in place.
- Bracing: Additional elements to ensure stability and prevent deformation.
Steps in Formwork Estimation
- Determine the Area: Calculate the surface area of the slab. This includes the bottom surface and any sides that require formwork.
- Calculate Material Requirements: Based on the area, determine the quantity of materials needed for shuttering, supports, and bracing.
- Labor Costs: Estimate the labor required for setting up, maintaining, and dismantling the formwork.
- Equipment Costs: Include costs for any equipment needed, such as cranes or scaffolding.
- Safety and Contingency: Factor in safety measures and a contingency for unexpected issues.
Detailed Estimation Process
- Area Calculation:
- Measure the length and width of the slab.
- For a rectangular slab, the area is simply length × width.
- For irregular shapes, break down the slab into smaller sections and sum their areas.
- Material Estimation:
- Shuttering: Typically, plywood or steel panels are used. Calculate the total area and add a percentage for overlaps and waste.
- Supports and Bracing: Determine the spacing of props and bracing based on the load and height of the slab. Use manufacturer guidelines for spacing and load-bearing capacity.
- Labor Costs:
- Estimate the number of workers needed and the time required for each phase: setup, maintenance, and dismantling.
- Include costs for skilled labor, such as carpenters and laborers.
- Equipment Costs:
- Include rental or purchase costs for scaffolding, cranes, and other necessary equipment.
- Factor in transportation and setup costs.
- Safety and Contingency:
- Ensure all safety measures are in place, including guardrails, safety nets, and personal protective equipment (PPE).
- Add a contingency percentage (typically 5-10%) to cover unforeseen issues.
Example Calculation
For a suspended slab measuring 20m x 10m:
- Area Calculation:
- Bottom surface area = 20m × 10m = 200m²
- Side surfaces (assuming 0.2m thickness and 60m perimeter) = 60m × 0.2m = 12m²
- Total formwork area = 200m² + 12m² = 212m²
Conclusion
Accurate formwork estimation for suspended concrete slabs involves careful calculation of materials, labour, and equipment costs. By following a systematic approach, you can ensure efficient resource allocation and successful project execution. Always consider safety and include a contingency to handle unexpected challenges.
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