Welcome back out to the jobsite and what I wanted to do today was
go through or start a series of videos
Three I think will end up being on
The materials we need to pour this concrete footpath, so I'm going to break it up into three videos
One will be perimeter for our formwork
Second one will be area for our reinforcement and the third one will be on volume for our to work out the actual concrete
So this will be the first one which is going to be primeter so
In order to form our mould for our concrete footpath we need to have some formwork
Generally timber although you can use steel a lot of professionals use a steel product, but for the average builder,
handyman timber is cheaper and
we readily more readily available, so we generally use that and
obviously it goes around the perimeter of our slab so the best method of calculation is to use
perimeter
There's a formwork by itself
So the best way to start a job will start working out something as always
make a sketch so
Sketch it out, it doesn't have to be the scale put your dimensions on it, so this slabs 5.678. long
800mm wide it's 75mm thick for a little footpath
So the first thing we need to do is work out the distance around the outside which is perimeter and the formula for perimeter
Is just a sum of all the sides, so we'll work our way around
5678 + 800+5678+500
add them all together gives us a total length of
12.956m for our
formwork around the outside of our slab but
If you go back and have a look at our formwork. You'll actually notice the formwork is longer
then
just that
exact measurement of the slab advance past
and not only does it run past by the thickness of the the formwork itself so that the thickness of this piece here and
the same here on on all sides you can see I've set the form lookup in these pictures
so that it runs past on each end
so I don't actually have to cut my formwork to an exact length
I can let it run past and the less you have to cut formwork the more reusable
it is later on so we always try and set it up so we can reuse our formwork so
Yep, even though I have worked out the exact
perimeter of my slab then it's not going to be really enough for my formwork so I have to allow a little bit more now
The other thing is over here in Australia timber comes in
standard lengths and
usually increments of
0.3 or 300 millimetres
and
depending on the timber they might start at about 1.8
although generally you know 2.4 about the shortest length of timber a would stock and
run up to anywhere up to about 6m for natural timber
So we need to make our lenghts of timber that we're gonna buy work
into these sizes, so
what I'm gonna do I'm going to take my 5.678 and I could go up to
5.7 but
You know that's really only another 22mm long, and they are timber
Yeah
It's going to be a minimum 35mm thick so
I'm going to round that up to 6m from our two long pieces on the edges. They'll let them run past a little bit
And my two ends I can add
800 and 800 gives me 1.6
so I can round that up to my shortest length there 1.8 to allow for my ends
so what I'm going to order from the timber yard would be
2 / 6m lengths and
1 /1.8m length so that gives me a total of
13.8 lineal meters of timber and that's how they're going to charge me they can only give me a price per
lineal meter of timber
So that's my timber workout. That's my formwork for around the perimeter and you'll notice in the picture
that we have a few pegs to hold that into place
Now have the number of pegs who put in does
differ depending on how thick your actual edge board is a thicker the edge board the less pegs are going to need to have
but as a general rule.I like to put one in every
800 to 1000
and obviously you need to have a couple extra ones in your corners
to hold both sides of the corner just so the slab doesn't want or the formwork doesn't want to separate in the corners, so
to work at our pegs
what we need is
the length of our slab or the length of our form work, which we were working on 13.8
a Peg spacing which I'm going to say is 800 and then we need to add a couple one one extra peg for each corner
so I'm going to say there's an extra four
four pegs for the corners
so
13.8 divided by 0.8 gives us 17.25 so let's say 18 pegs
plus 4 for the corners and that gives us a total of 22 pegs
for our job
So that's what we need to do
in order to work out the formwork
for our simple concrete footpath and the pegs that we need for
So in the next video what I'm going to do. I'm going to look at how we work out how much
Reinforcement we actually need to put the mesh or the reinforcement into this slab