So in this video we back out on the
Site from the marking up video and what I'm going to show you this time is how we go about
taking our setting out and then creating formwork
for a slab on ground
This is a slab on ground
as
You can see the main feature of this slab is that it has a step or a rebate
So what happens when we construct the the house
Our brick veneer goes on the lower edge of this step and our timber frame sits up on the top of this step
that allows us to put our flashing in and
Form weep holes in our Brickwork
so we can drain any moisture
any water that gets behind our brickwork can come out and not make any contact with our timber frame, so that's what we
need to achieve, so
Remember from the marking out video. We got all the our string lines in place
Look something like that, and now we can
Start to create our formwork so the first thing we need to do pick a side any side and pumb down
Your main points in fact what I would do is I would go around the whole site and I would
Transfer these marks down onto the ground with
Some spray paint or a bit of Lime or scratch mark on the ground whatever you've got available, the plumb, or use a
Spirit level or a plumb line a transfer these marks onto the ground
Then we can go around and actually lay our timber boards in place
or our Edge boards
Now because this is formwork. We don't want to necessarily cut these timbers to exact length
So where possible we want to actually extend these past our points
This one is actually cut tight or cut in between
But you'll see a lot of the other ones in the video will be extended past
So where you can don't cut formwork to length because you want to be able to reuse it
Okay, I'll get rid of the string lines here shortly, so what we have to do is we put these
pegs in to hold our Edge board in place
This is one method of supporting the Edge boards. I'll show you another one shortly
the disadvantage of this method is that
When you drive these pegs in if they hit a rock in the ground or you got particularly hard ground
It's very hard to keep that Edgeboard exactly where you want it to be
so there is a way of getting around that I'll show you in a second, so
first thing we have to do support our Edge boards, at both ends
And then we need to get it straight, so the best way to do that
Grab a block of timber we actually need three all the same same thickness one block goes on this end
now the block block goes down on the other end and
We take a stringline and then we wrap it around the blocks
To a nail here, take take it around the block up to the other end
once again a nail tie it off tight, and then we can put a block in the center and
if the block slips between the Edge board and the string line
Without any gap, then the Edge board is straight so we can put a peg
behind that
And we just repeat that process as many times as we need to to get our pegs in now
Depending on the Edge of this the thickness of this edge board
You're probably going to want a support Roughly every metre
Behind your Edgeboard it depends on how thick it is
Whether it's going to bow or not under the weight of concrete, so that's a decision you have to make yourself, but roughly
Every metre, you'll need a support
Okay, so there's our first Edgeboard in
Now we're going to swing around and do our next one so as I said before
You can either put your stringlines back up which is a bit of a pain or you can already have this mark transferred down
Put in another Edgeboard now in this case
one Edge board wasn't going to be long enough so we had to join it with a cleat and
The process is the same
Except this time to support the Edge board. I'm going to use two pegs and
a ledger
so this just means I can drive these pegs in anywhere pretty much well
they don't have to touch the edge board and then I can slide this the ledger in till it touches the back of
The Edgeboard now the only thing you need to be careful of is that this Edge board is sorry this ledger is level
So at the moment that looks like you're using a lot more timber
Than what you used during using this method which you are, but you'll see when we actually form the rebate
It'll become a little bit more efficient. So one support at that end
support at the other end
stringline in the face again with our blocks and we straighten out the
straighten out the formwork
put a support in the middle
Keep checking up with your block and put all your supports in
That's the process and you just have to work your way around
the entire site
until you get that done, so
that's the first layer or the bottom step of our rebate, so now we need to do that here at the top step
so what we're going to use is another peg and a ledger and
that peg and ledger the pegs this can be back whatever length your ledges are and
We need to sit this
top of this ledger
150mm
so if you measure 150mm from the back of
the this Edge board
To the face of your ledger [that] will mean [that] it will be 150 Ml from the face of this Edge board
to the face of the [Edge] bulb we're going to put on here and
We just do that all the way along
So that's one method there are brackets that you can purchase or you could have made
that this simply sits over your bottom Edge board and
Then you screw them on
To the bottom of the Edge board the bottom side
you then sit your
Second Edge board on here, and they screw into the back of that, so that does the same job a little bit quicker then
using the Timber Edge boards
but if you're going to um if you're not going to do it very often then may not want to go the expense of
purchasing these brackets
So we'll go back to the timber method. So that's that Edge done. Let's see on the other side where we use the different method
Now we've already had that second peg in place
so we just had to put the ledger in make sure it's overhanging the 150mm and
That's that's complete so realistically with this system only extra timber. We're using is that bottom ledger over this system
So it's a little bit more efficient than it used to look I
Personally think this is a better way of getting nice straight Edgeboards using this method. Can't get your edgeboards of straight
again, we have to go around the entire site and do that and
Then once that's done. We go around and put in our top Edge board and
We've got our rebate formed
Can have a little bit of look around
Okay, so once we've got our edgeboards in and all their formwork done we then have to think about filling up
the center of the Field of the slab so one of the methods is quite commonly used nowadays is a
styrofoam
Pod
In Australia they call them waffle pods
Because this you know the inside of your house is not going to get heavy traffic. Just furniture and people
You really don't need to have I said that's 200-300mm thick so what they do is
They put these pods in and that just means that for the majority of the slab
The thickness of the Concrete is only about 100mm
Which is heaps if you're going to have an area in your house that was going to take heavy loads like possibly a garage
Or somewhere
were your going to have a pool table or, your know, a spa or water bed that might have point loads on your floor
You would have to
Consider that in your design and possibly remove the waffle pods in those areas, but that's up to your structural engineer to work out
So the waffle pods go in now instead of using waffle pods. You could use dirt or sorry controlled fill and
Sand but nowadays waffle pods are the common thing
Once your waffle Pods are in
You place in Trench mesh in the lower half
to
reinforce the bottom of these beams that will be formed by waffle Pods and
Then on top of that on the top of the waffle pods you put in your fabric reinforcement or the mesh
Making sure all the reinforcements to your slab
And of course once that's all done. It's been inspected and
you pour the concrete
Take and see now a little step here has been formed in the slab
and
There's our slab formed now once you pour the slab generally you should take about seven days
before you pull this formwork off a
Lot of contractors and concrete and professional concreters will do it on the same day
But the risk is that if someone or something was to run along one of these edges then the concrete could possibly fall off
so you really want to live it seven days take seven days to to get some strength about it and
Then realistically all it takes 28 days to reach its designed strength
There we go. There is our slab on ground with our rebate all formed up
Ready for our frames and our bricklayer