A waffle slab is a type of reinforced concrete slab that contains square grids with deep sides. Grid slabs are appropriate for spans between 9 and 15 meters and live loads around 4 and 7 KN/m2. Formwork is extremely costly, even when pans are used.
What is a Waffle slab?
This type of slab has a two-way grid of ribs or beams on the underside, forming a waffle-like pattern. It offers enhanced strength and stiffness while reducing the amount of concrete used.
What are the types of waffle slabs?
Based on the shape of PODS (PVC trays) they are classified into different types. The main two types are:
- Triangular POD system
- Square POD system
What is the Waffle Slab Reinforcement Detail?
The reinforcement detail of the waffle slab is divided into 5 sections. You can watch the video to get a better understanding of all of them as they are mentioned in it.
Waffle slab cross-section reinforcement detail
Waffle Slab Middle Support Reinforcement Detail
How to design the waffle slab?
The design of the waffle slab is similar to the ribbed slab. The main difference is that the ribs span both directions. A waffle slab’s design must take multiple variables for load distribution and strength into consideration.
Now, we will tell how to design waffle slabs along with all of the waffle slab dimensions.
|10”-29” (25.4-73.7 cm)
|Rule of Thumb
|130 mm (5 in) to 150 mm (6 in)
|Distance Between Ribs
|915 mm (3 ft)
|Height of Ribs and Beams
|1⁄25 of the Span Between Columns
|24”-40” (61-101.6 cm)
|Solid Area Around the Column
|1⁄8 of the Span Between Columns
|Equal to Ribs
|25’-55’ (7.62-16.77 m)
|30’-80’ (9.14-24.38 m)
|19”, 30” (48, 76 cm)
|8”-20” (20-51 cm)
How to construct the waffle slab?
The construction of the waffle slabs is not complex and is made in different ways. There are several steps you have to follow. Numerous components contribute to the formwork, including steel bars, waffle pods, cube junctions, hole plates, clits, and horizontal and vertical supports.
- Formwork: First build the formwork to support the slab and the rib.
- Arrange the pods: Now, arrange the pods on the framework according to the project requirements.
- Reinforcement Installation: Place the steel reinforcement for the slab’s durability while being manufactured.
- Pour the concrete: At the last carefully pour the concrete mixture into the formwork.
What are the advantages and disadvantages of the Waffle slab?
|Able to carry heavier loads
|Not suitable in typical construction jects
|Span longer distance
|More complex to install
|Light in weight
|Required supervision and skilled labor
|Used as both the roof and floor slab
|Larger, more expensive formwork material quantities are required.
|Suitable for spans of 7M to16M
|Can create floor-level issues
|In the framework, a light framework is required.
|Suitable for flat areas
What are the applications of the Waffles slab?
Waffle slabs are usually used where large spans are required to avoid many columns interfering with the space.
- Public Buildings
- Commercial and Industrial Structures:
- Educational and Hospitality Institutions
- Residential Construction
- Aesthetic Designs
- Seismic Performance
- Hospitality Sector
- Large-Span Structures
- Highly Loaded Structures
Frequently Asked Questions:
What is the purpose of a waffle pod slab?
The main role of the pod is to create a strong structure to prevent the signs of cracks and damage.
Why is the waffle slab the best slab type?
Compared to other standard slabs, waffle slabs are more affordable and provide strength and durability with less concrete.
Are waffle slabs more expensive?
The expense of the waffle slab depends on several factors. Generally, building the slab is cheaper than a traditional concrete raft slab. However, the framework material is more expensive.
One of the best choices in construction quickly gained popularity. Waffle slabs are usable for spans greater than 40 feet (12m) and the slab is stronger than the other types of slabs like flat slabs, one-way, and two-way slabs.