The right floor for your build

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When building, you may put a lot of thought into the floor coverings, but what about the sub-floor structure? Both are important to ensure a sustainable result. Lance Turner surveys the options.

When building a home, often very little thought is given to the type of flooring and sub-floor structure used. Yet different sites need different materials, with some being far more appropriate for particular sites. The design of the rest of the house will also help determine the type of floor and sub-floor used.

Your architect will have good ideas about the best flooring system to use, based on their experience with the type of building system you are using and the site specifics. But it helps to have a good understanding of the flooring systems available, so that you can consider the pros and cons of different systems and materials, and ensure that your sustainability or other requirements are met.

So let’s take a look at the most common types of flooring systems (or, more accurately, sub-flooring systems), the materials most commonly used and the types of flooring materials they can support.

Flooring requirements

A floor/sub-floor system must obviously be able to bear the entire load on top of it, potentially including the house, contents and occupants (some floor structures, such as upper floors, will only need to support the contents/occupants).

The floor’s footing system must be suitable for the type of soil you have on your block. A soil report will be required which will tell you your soil type and how reactive it is. Reactive soils are soils with a high clay content which swell when wet and shrink as they dry. This expansion and contraction can cause structural cracking, sinking and other site issues. See www.bit.ly/2oKu9GC for a quick rundown of soil types.

The level of insulation required for your home will also be a factor in the type of floor you select. If you are in a cold climate then you will need a highly insulated floor, so an insulated slab or a floor on stumps that can be insulated underneath will be required.

Of course, durability is also important: the floor must last the life of the home—for example, you don’t want to have to be restumping in 10 years due to degradation of the stumps or soil movement.

Thermal mass must also be considered if your house design makes use of it. A slab provides high levels of thermal mass, although heavyweight walls (on the room-side of the insulation) tend to provide better thermal mass both in winter and summer than do concrete ground slabs. Other floor types can have thermal mass added using a number of methods, from thick ceramic tiles or slate, to adding PCMs (phase change materials).

Read the full article in ReNew 143.

Download the summary tables here.