Technique is the key then? gotcha
I'm now in two minds as to what the best approach is:
1) Get ready mix delivered for £275 but have to barrow all of it, against
2) Mix my own, at my leasure, for £320 max. Can be done over any number of
days if I split the work into smaller slabs. I still have to barrow all the
materials, but not against the clock, and not with the water mixed in with
3) Get two lots of ready mix, on different days, ensuring the two slab
halves are down long before the concrete starts to go off. This puts less
pressure on the barrow boys but increases to cost to £165 x 2 = £330
Mix your own. It won't kill you. You obviously want to give it a go. If
you do it in strips, you can choose whether to keep going and do it in a
day - or take a couple of weeks doing it, strip by strip - the concrete
won't care. You can, as suggested, drill some over-size holes in the
formers and use some rebar to bond the strips together. I have never
bothered other than where I wasn't too happy about the sub-base.
I'd lay a few poly tubes down under the slab. Two days after you finish,
you will find that you want to put a water pipe/cable/phone line across
where you hadn't thought that you would need one.
lol obviously want to give it a go. Perhaps that's true, I'd just not
Yes, I think it would be best rather than a race against the clock to move
all the premix from the roadside.
Great minds must think alike. I've got drainage, hot and cold water, TV,
cat5 and phone wires already down!
Thanks for all your advice, Sue. This just leads me now into the murky world
of what's the best mix to use? The builder's merchant supplies aggregate
which is fine sand mixed with fine gravel. I want something really strong
and don't mind paying for extra cement to achieve it so do you think a 4:1
mix is suitable? Bearing in mind I'm going to build a big heavy log cabin on
top, quite possibly with a hot tub inside it, not to mention some motor
bikes and machinery.
Your log cabin manufacturer will have given you the spec for the base.
Stick to that.
Cement+sand with no gravel has zero strength - it is the gravel that
provides the strength. The cement merely bonds the gravel together - too
much can leave you with a weaker concrete in the same way as too little
can. The sand makes the cement go further.
I use 1:2:4. If I want it stronger, I make it thicker and stick in
reinforcement. Easy to do - lay the mesh on the sub-base/dpm with a few
loops of string with knots 2" above the mesh - pour and level the
concrete, then gently pull the loops until the knots show. Cut the
loops, pull out the string and do a final tamp down and level. Easier
than playing with stand-offs and trying to pour the concrete through the
My workshop has 150mm with two crossed mesh reinforcement, one at 50 and
another at 100mm. It has to take a 2+ ton milling machine, plus a few
other toys like that. I worked on the premise that it was easier to go
for overkill when I built the thing, rather than wish I had, later. My
local building inspector was dead impressed - I think he thought I was
really building a nuclear bunker..
I'm building the cabin myself so have no spec to work to.
Well you live and learn. I thought the strength all came from the cement!
I take it that is 1 cement, 2 sand, 4 gravel?
I'll have to ask the builders merchant which ratio of sand to gravel the
aggregate comes in, but one would think it is a standard mix if that's all
they supply to the trade.
Thanks for the string loop technique, I was wondering how it was done
without the mesh just sitting on the bottom or it standing on blocks.
lmao. I'm kind of wanting the same strength, for overkill as you nicely put
it, but was hoping 125mm with one cross mesh would do the trick?
Probably about the same distance - up the drive, down the side of the house
and down the back garden. I thought it went very easily. The trick was
to have two people with barrows (three for the first few loads to get
started) and two more spreading and levelling. The lorry was gone after
30 minutes and all that remained was final smoothing and levelling. I
would have thought yours would not take that much longer. The other thing
to watch is that your shuttering is strong enough to take the cement rolling
up against it and you have boards to enable you to push the barrows over the
shuttering to where you want to tip. After my experience I wouldn't dream
of doing it any other way. Bear in mind also that if you have the muck
tipped at the roadside you have the additional task of shovelling heavy wet
cement into the barrows whereas the mixer lorry pours it straight in.
(If you can\'t laugh at life, it ain\'t worth living!)
I think this really comes down to a decision of wether I want a race against
the clock to move the wet premixed concrete from where it is dumped at the
roadside, against moving materials at my leasure then doing the mixing
myself in smaller portions, laying a number of slabs.
The premix lorry says they can hang around while it is tipped into barrows,
rather than quickly into one pile, but then they'll charge me extra for
Thanks for your advice, especially about the strength of shuttering. Cheers
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