We all know how important a solid foundation is to a new house. Choosing the suitable slab for a home is probably the most critical part of the entire building process. Nowadays, the two main types of slabs used to build houses in Australia are the waffle pod slabs and raft slabs. This article will discuss the pros and cons of each of these two types of slabs.
Here is how to install a raft slab: a trench roughly 450mm wide and 450mm deep is dug under the exterior walls and load-bearing walls (refer to the engineer’s calculations for how deep to dig). A reinforcement cage is laid in the trench, and then a concrete slab about 100mm thick is poured on top of the whole to form a concrete slab that covers the entire floor area. For short, excavation is required for ground preparation, and the slabs are cast against the ground.
Waffle Pod Slab
Waffle Pod Slab constructed on the ground. They consist of a perimeter footing (edge beam) and a series of narrow internal beams (strip footings) at one metre nominal centres running each way. The whole footing and slab system is constructed on top of the ground. The waffle foundation does not require excavation, and the concrete slabs are cast onto polystyrene void formers.
Raft slab VS Waffle Pod Slab
Many people are asking which kind of slabs are better? Why volume builders prefer waffle slabs? I will analyse the pros and cons of these two types of slabs from the builder’s perspective.
The cost of waffle slabs is significantly lower than raft slabs. This is one reason why many builders and contractors are opting for waffle pods instead of regular raft slabs in their new projects.
Conventional raft slabs require excavation before installation, while waffle slabs do not. Raft slabs also take more time to install than waffle slabs. The polystyrene voids are also very light and easy to cut, reducing the overall labour involved.
Secondly, Waffle slabs are innovative because they use polystyrene void formers rated for efficient thermal insulation, achieving a higher energy rating. If a traditional raft slab is used and the energy rate requirement is not meet, we will need to upgrade the insulation or use thicker glazing, which can further increase the cost of the building.
These factors usually mean that waffle slabs are much cheaper than traditional slabs.
Traditional raft slabs are stronger and more durable than waffle slabs. Although raft slabs cost more to install and achieve less energy score, many owners of high-end projects tend to choose raft slabs when they have a sufficient budget. Raft slabs are cast against the ground, whereas waffle slabs are cast onto polystyrene void formers and strips of concrete. An overloaded raft slab is less likely to crack because it is cast onto the ground. The area under a waffle slab will expose If the soil around your house gets eroded or washed away. Exposed areas under the Waffle Slab can attract reptiles and other wildlife seeking Shelter.
Raft slabs can be applied to a broader range of soils conditions, while waffle slabs are suited to lightly and moderately reactive clay sites with very flat grounds. If the soils are very reactive, waffle slabs need to be reinforced with concrete piles underneath determined by an engineer, thus losing the cost advantage.
In general, we homeowners do not have to worry too much because the Building Code of Australia (BCA) deem to satisfy the performance requirements. Whichever building method is used must achieve the performance results and meet Australian standards. So it is more important that we trust the engineers to make our best choice. Whichever slabs you choose, Integrity New Homes can help you install, and we are pleased to provide you with more information. Contact me if you need any help.
我们都知道地基对一个房屋建筑的重要性。为房屋挑选和设计合适的地基可能是整个建筑过程中最重要的部分。现如今澳洲建房主流的基础有传统阀式基础（raft slab）和华夫阀式基础( Waffle Pod Slab)这两种类型。今天我们这篇文章就来讨论下这两种主流基础各有什么利弊。
华夫阀式基础( Waffle Pod Slab)
华夫基础通常不需要挖掘，在地面上用模板限定出需要灌注混凝土的范围，在其中按设计图纸放置约1米见方的泡沫方块（ polystyrene pods），然后整体浇筑约100mm厚的混凝土板，整个基础悬浮于地面。简单地说华夫基础不需要开挖，混凝土板底下是泡沫方块。