How do you build a raft slab?

How do you build a raft slab?

Here’s the process for building a raft slab for a house.

1. Step 1 – Set Out.
2. Step 2 – Edge beams.
3. Step 3 – Steel reinforcement for raft slabs.
4. Step 4 – Edge beams filled.
5. Step 5 – Sand fill.
6. Step 6 – Excavate strip footings.
7. Step 7 – Damp proof membrane.
8. Step 8 – Slab reinforcement.

How is a raft foundation constructed?

A raft foundation is constructed by first excavating the ground to a uniform, flat level. Then, a waterproof plastic sheet is laid over the earth, and a thin 3″ layer of plain cement concrete (PCC) is poured just to create a perfectly flat and level base for the foundation.

How do you install a raft foundation?

A raft foundation spreads the weight of the building over the whole ground floor area of that building….How Do Raft Foundations Work?

1. The soil removed down to correct depth.
2. The foundation bed is then compacted by ramming.
3. Lay reinforcement on spacers over the foundation bed.
4. Pour the concrete over the reinforcement.

How is a waffle slab poured?

The process behind concrete waffle slab construction is objectively straight forward. The concrete is poured on top of void forms called Waffleboxes or waffle pods. After Waffleboxes are arranged, post tensioned cables are installed in the waffle slab formwork to hold the weight.

How thick is a raft slab?

Raft foundations (sometimes referred to as raft footings or mat foundations) are formed by reinforced concrete slabs of uniform thickness (typically 150 mm to 300 mm) that cover a wide area, often the entire footprint of a building.

Which slab is better waffle pod slab or raft slab?

The main benefit of using waffle pod slabs is that they are drastically cheaper than traditional raft slabs. Waffle pod slabs use foam void formers to create the volume required for the ground slab. Conventional raft slabs, on the other hand, create the slab entirely from concrete and reinforced steel.

How thick is a raft foundation?

They are generally constructed on a compacted hardcore base (perhaps 100 mm thick). A layer of blinding concrete may then be laid to allow formation of the raft (typically 50 mm) with a waterproof membrane above.

How thick is a concrete foundation slab?

6″
A slab foundation is made of concrete that is typically 4″–6″ thick in the center. The concrete slab is often placed on a layer of sand for drainage or to act as a cushion. Houses built on a slab lack crawlspaces, and there is no space under the floor.

What are the disadvantages of waffle slab?

The disadvantages of waffle slab are as follows:

• Require greater floor-to-floor height.
• Requires special or proprietary formwork which is costly.
• requires strict supervision and skilled labor.
• Difficulty in maintenance.
• Not suitable in highly windy area.

What is waffle raft slab construction most suitable for?

Waffle raft slabs are a better way of building concrete slabs for new homes, extensions and commercial or industrial buildings.

Why is it called raft slab?

The Raft Slab: With an interesting name, it can make you think that the slab floats like a raft. The depth and spacing of the edge and stiffening beams is dictated by the type of soil the slab will be sitting on. Sandy soils require no stiffening beams or shallow edge beams.