if you're building in australia chances are you will have a slab on ground in your project
reinforced concrete slab on ground has been used in many parts of australia for the past
decades especially in the residential building industry so in this video we're gonna go through
five steps to building a residential reinforced concrete slab on ground
along with a couple of tips that can save you money and time
but please before you build anything sick for engineering advice the last thing you want to
deal with is foundation problems trust me it's a nightmare you will need engineering
drawings as per the site classification which is based on the soil reactivity for your specific
site having said that get in touch with Incode engineers in brisbane which is the sponsor of this
video and the company that i work for i'll leave the link up the website in the description below
so before you build anything get in touch with us and we'll make sure we provide you a stress-free
project before we jump on step number one i'll give you a quick run through the drawings Incode
engineers would provide you for the construction of a rough slab first things first have a good
read of the structural notes each and every note on this page is relevant to your specific project
here you find information on site preparation form work foundation notes earthworks
retaining wall slab on ground which is our main focus in this video
concrete notes such as concrete grade slump cover construction joints control joints and
much more moving to sheet s2 the ground floor slab plan shows a layout of the footing in slabs
how thick the slabs are for example this one is 100 thick while this other one is 130 thick
down here you've got a couple of the notes and legends specific to the ground floor slab plan
for example these diagonal bars a crack control bars which should be placed in all negative
corners these little parallel lines represent dollar bars to connect slabs that will be done
in separate pores this hatch denotes wet area set down where you might have a bathroom for example
these dashed lines represent the ground beams and if we move to sheet as stand or page of details
we'll show you how we want these foldings should be constructed so here is an example
of a ground beam slab thickening edge thickening rebate detail for small steps
on these drawings you will find size reinforcement cover and everything you need to build the
structure now that your familiarized with the structural engineer drawings let's get
started with step number one site preparation and excavation but before you start any work
get your surveyor to provide you all information you need about the site you don't want to build
your house in the wrong location the actual ground preparation starts by scraping off
the top soil and any loose material then you're going to level and compact the subsoil
which has just been uncovered a reasonably uniform foundation is essential to long-term performance
next you're going to dig out the shape of the edge and internal beams and any necessary surrounding
drainage trenches we recommend using a blinding layer of sand because it helps to protect the
membrane on rough ground step number two install service pipes and the membrane
at this stage the plumber will install all the pipes which are to be covered by the slab turbine
mesh will also have to be fitted to all pipes that black plastic you see on top of the soil
is the vapor barrier as the name suggests it's a barrier against vapor rising through the soil and
bringing moisture into the house remember it's not waterproofing water proofing a concrete
slab is a completely different process if you're located in south australia or new south wales
you should use a damp proofing membrane instead of a vapor barrier damp proofing membrane is
high impact resistant while vapor barrier is medium impact resistant step number three
install the reinforcement steel reinforcement is necessary in all edge and internal beams as well
as in the slab panel typically the beams are 300 millimeters wide with a trench mesh in the bottom
the slab on the other hand will have sheets of mesh everywhere if you lay this too close to the
ground it will rust and fail that's why you need bar chairs bar chair is a plastic support placed
under the reinforcement to hold the steel away from the ground and prevent corrosion another
important point here is that in case you decide to pour a strip footing first and then this
slab in the second pour you must install starter bars in the strip footing to connect to the slab
you also need three and twelve reentrant bars two meters long to all negative corners as i've shown
on the plans step number four place the concrete and finish the slab surface
for most of the jobs concreters will pour the footings and slabs using a concrete truck
and a pump you can use a boom pump or a line pump if it is a large project you're better off using
a boom pump if you decide to use a line pump or something else just be careful not to knock the
bar chairs over the minimum concrete grade to be used is n20 which slump between 80 and 100
millimeters and 20 millimeters aggregate just a side note if you're doing a polished concrete slab
i would recommend bumping that up to n32 grade concrete and using sl 81 or 92 mesh
do not add water to the concrete on side it does get easier to work with however it will get weaker
crack more and result in a poor surface finish a mechanical vibrator should be used to compact the
concrete hold the vibrator straight up and keep it in the same position until bubbles stop rising
to the surface this will ensure the concrete is evenly consolidated and free from entrapped air
make the concrete surface smooth and level with a skating board last but not least step number five
cure the concrete slab this is one of the most important steps if you want to keep your slab
free of visible cracks in simple terms as the concrete dries out it shrinks and if the concrete
shrinks before it gains enough strength it cracks so curing involves holding water in the concrete
and allowing it to gain strength cure the concrete continuously for at least three days or seven days
depending on the exposure classification you can also use curing compounds to reduce the
loss of water following these five steps will give you a high quality slab on ground that
will last a lifetime if you have any questions about slab on ground just leave a comment below
don't forget to like the video and subscribe to the channel and i'll see you next time