Cost-Efficient Slab Construction Using Hollow Clay Pots (Ribbed Slab System)

In the current climate of soaring construction material costs—especially cement, granite, and reinforcement steel—innovative building methods are no longer optional, they’re essential. One such method that’s gaining attention for its efficiency and cost-saving potential is the hollow clay pot slab construction, also known as the Ribbed slab system

What is Hollow Clay Pot Slab Construction?

This is a slab system designed to reduce the overall volume of concrete and reinforcement required without compromising structural integrity. It does this by incorporating hollow clay bricks (pots) within the slab, replacing the mass of solid concrete in non-structural zones. The result? A lighter, more economical slab.

Step-by-Step Breakdown of the Construction Process

1. Formwork Layout (Soffit of Slab)
The formwork is first prepared by cutting it into strips of 200mm width. Each strip is spaced 200mm apart from the next. These gaps form the ribs of the slab—where the main reinforcement will be placed.

2. Reinforcement Placement
Within each 200mm gap, a 100mm wide reinforcement zone is established, allowing for 50mm concrete cover on both sides. This ensures adequate protection for the rebars against environmental factors.

3. Clay Pot Specification and Placement
The clay pots used in this project measure 230mm x 270mm x 150mm and are laid horizontally on top of the formwork strips. These pots act as permanent fillers between the ribs.

Let’s break down a practical example for clarity:

- Room Size: 6000mm x 3450mm
- Formwork Lines:
- 6000 ÷ 450 = approx. 13 lines of formwork
- Clay Pots per Line:
- 3450 ÷ 230 = approx. 15 pots + 1 (to cover tolerance and edge) = 16 pots

Note: This calculation represents just one section of the slab. Main beams will typically divide the slab into multiple compartments.

4. Hidden Beams and Stirrups
Hidden beams (also known as secondary or concealed beams) run parallel with the length of the formwork strips. Stirrups or triangular links for these beams are cut with the following components:

- Bottom: 100mm
- Two triangular sides: 150mm each
- Hooks: 80mm each

Total length per link:
100 + (2 × 150) + (2 × 80) = 560mm
With allowances for lapping, this rounds to 580mm.

5. Top Mesh and Reinforcement
Once the clay pots and ribbed reinforcements are in place, a steel reinforcement mat (as designed by the structural engineer) is laid across the entire slab. This could include:

- High-yield rebars
- BRC mesh (British Reinforcement Concrete mesh), depending on design needs

This final mesh ties everything together and ensures load distribution across the slab.

The Cost-Benefit Edge

This method drastically reduces the volume of concrete required, as the space occupied by the clay pots would otherwise have been solid concrete. Likewise, reinforcement usage is more targeted, reducing material waste and labor hours.

In Summary:

- Slab Thickness: 200mm
- Major Savings: Concrete volume, reinforcement, and formwork complexity
- Added Benefit: Thermal and acoustic insulation from the clay pots

By intelligently rethinking slab construction, builders can manage costs without sacrificing quality or structural integrity.

Hollow clay pot slab systems offer a smart, scalable solution for both residential and commercial projects.

Stay Constructive, Stay Smart.

Oluwatobi Yinusa

Posted By :
Oluwatobi Yinusa

: 07 Apr 2025 02:49 pm

Comments

Emmanuel oluwaseun 07 Apr 2025 03-21:pm

Nice one Estimator
Isaac Sanusi 07 Apr 2025 04-08:pm

Weldone chief QS. Great insight
Moses Awoyemi 07 Apr 2025 04-17:pm

Nice One My Chief Qs Thank you Sir.
Abdulrafiu Ibrahim 07 Apr 2025 06-03:pm

I’ve watched you conquer the hollow pot slab on your WhatsApp status daily, thank you for carrying us along. \r\n\r\nI don’t read this lightly as I know it’s not just a theory but proven but a proven fact borne from your sweat and diligence on site.\r\n\r\n\r\nKeep it up boss, we Dey your back
Etim Joseph Sepp 07 Apr 2025 06-11:pm

The Chief Quantity Surveyor
Tolu Samson 08 Apr 2025 08-21:am

This is a job well done.
Fejiro Victor 08 Apr 2025 09-14:am

Interesting, thanks for sharing
Sodeeq Moruf 17 Apr 2025 08-42:am

Thanks for sharing sir