Concrete pad in two parts advice please.

[Martin Hocking]

I’m doing a concrete pad this weekend and I’m getting a bit stretched for time on the prep work and just in case I’m considering doing it in two halves as a plan b.

I’m mixing it myself and It’s 12ft x 24ft x 5 inches and I bought some 6mm mesh to help stop it cracking.

My question is that if I have to do it in two parts what should I do with the mesh? Just cut it flush with the join? Leave it overhanging and drill some holes in my piece of timber blocking it off? Not bother putting it in in the first place? Have another sandwich and stop panicking?

Any advice greatly appreciated it’s been a very busy week so far…

 

[Smallfry]

Definitely mesh overall. assuming it is on pillars, some batten 2x2 underneath, and 4x2 or whatever above then pegged into position. Some will leak through, but not really problem.

Doing all that by yourself ? Its gonna be a hard slog. Whichever you do, make sure it is covered and kept moist for a day or two, to help stop surface cracking.

 

[julianf]

I would, personally, not consider breaking the job. I would, instead, make sure everything was just where I wanted it, as set up as I possibly could be, and just get it done in one hit when I could.

 

[addjunkie]

I would, personally, not consider breaking the job. I would, instead, make sure everything was just where I wanted it, as set up as I possibly could be, and just get it done in one hit when I could.

I concur….get it set up, concrete lorry and plenty help. You wont regret it.

 

[jmp49]

I poured my barn workshop in 3 pours of reinforced with fibres and mesh because it was too much to get down and floated in one hit and needed 3 full wagons so it cost the same if we took it all on one day or spread over different ones. I trimmed the mesh to the boards, but I put heavier rebar between the 3 sections tied to the mesh and pierced the boards separating the sections for the rebar to pass between sections and poured the 2 outer pads first. Some leaked out around the rebar holes but not enough to worry about. You have to cut the boards out, so they're sacraficial and cant be reused, unless you can slide them along the rebar stubs to the ends. I just levered mine out with a pry bar and split them round the bars.
I've done quite a few huge pours and the worst thing is when a bunch of people promise to help, and then on concrete day mysteriously disappear and are uncontactable. You cant go chase them up because your already in a jam and the slurm waits for nobody and you end up with it going off before you can finish working it, and powerfloating at 5am barely able to lift your own eyelids. I am completely happy with breaking up the job and not having to rely on the whims and reliability of others.

 

[dobbslc]

slurm

 

[Morrisman]

Definitely mesh overall. assuming it is on pillars, some batten 2x2 underneath, and 4x2 or whatever above then pegged into position. Some will leak through, but not really problem.

Doing all that by yourself ? Its gonna be a hard slog. Whichever you do, make sure it is covered and kept moist for a day or two, to help stop surface cracking.

When I had mine laid I soaked it throughly after the guys had done the finally troweling, or whatever they call it, and put a tarp over it for several days. It was in the middle of the bit of a heatwave we had four years ago. I’ve been advised by a concrete expert to make sure it stays wet for several days.

12’ x 16’ x 6” and I paid £1200 for the concrete delivered, installed and skimmed. I’d did the shuttering myself beforehand. No steel in it though.

I left the hose under the tarp, and turned the water on gently for a bit every day, for several days.

 

[julianf]

My garage is 3.6 x 5.somthing mtrs. 150mm slab.

Access was too bad for premix.

Two of us, two cement mixers, and, surprisingly, we were done by lunchtime (?!?)

As above, the trick is to have everything to hand. So you're literally chucking buckets of aggregate and a half bag into the mixer and pouring it out. You don't want to be moving anything more than half the distance of the slab on the day.

Again prep and planning is everything, and then it's never as much work as you think it will be.

I feel like I'm being patronizing saying this - apologies.

 

[julianf]

Oh, and get the plastic bag cement with the admix.

Not only does it mean you can safely leave it out the night before but it also seems to mix so much better / quicker. Less balling in the mixer.

 

[Mark 5]

Slurm is good so long as it aint animal slurry.

 

[Nomad]

Hi. Who is doing the work / how many bodies?

The slab for my garage was about the same size, I found a gang of 3 local builders that did the job for cash.
They did the shuttering in a couple of hours then I put mesh in (several 6x8 fencing panels) as reinforcement.
They booked the cement to be poured and they did everything including floating it off.

A great result for me and decent beer money for them, no way I could have done that size myself - or get such a good result even if my usual helper was there with me.

 

[carbonarc]

With an allowance for waste the slab contains just short of 3.8 cubic metres which weighs close to 9 metric tons.

 

[hunter27]

We have just laid 2 slabs an my sons house and expect to lay the final one next week, I was surprised to find that buying the materials from local builders merchants and self mixing was going to cost more than ordering from a company that mix it on site and barrow it to where you want it?
Make sure your depth/grade is even, it's easy to be over depth and need more concrete to level, soak the ground before you lay on it so it doesn't soak out the moisture from the concrete, plenty of control lines so eventually when it does crack it will crack in a straight line.
Unless you have a large mixer I think you will struggle to do that size without the start point setting up before you have finished the pour.
Hope it goes well for you.

 

[Pigeon_Droppings2]

My garage floor was done in 2 halves (not by me).

The way the builder did it was screen the mesh in...but then he didn't fill up to the edge of the screen so mesh was left exposed.

He did cover it well as I recall...finished next day I think.

I've had zero issues with the joint.

 

[Agrismith]

This is the stuff for dividing pours in a slab.
Put it across as a divider l, bedded down on a little bit of concrete, push some bigger down bars through the holes (10-16mm) and chuck some type , ballast mud or similar on the empty side so not to much runs out the holes. When section 1 is poured just clean off the type 1, ballast mud and pour section 2 leaving the k form in place.

K Form Screed Rails | Lemon Groundwork Solutions Shop

K Form Screed Rails - K35, K85, K135. Enables adjoining bays to be poured consecutively, Pre drilled holes in base for anchoring with mortar.

www.lemon-gs.co.uk

 

[Martin Hocking]

Thanks for the replies everyone. Really helpful as always.

I haven’t got time to reply in full at the moment but I have read all the replies so far, and all of them have been helpful. The forum wins again!

 

[Smallfry]

Thanks for the replies everyone. Really helpful as always.

I haven’t got time to reply in full at the moment but I have read all the replies so far, and all of them have been helpful. The forum wins again!

If you were nearer, I would come and give you a hand, but I have some paint drying that I need to keep an eye on, plus I promised SWMBO that I would tidy my sock drawer.

Seriously though jmp49 is dead right about promised help evaporating when it comes to it ! We had the same thing here.

 

[julianf]

Seriously though jmp49 is dead right about promised help evaporating when it comes to it ! We had the same thing here.

I was booked to help a friend. A lot of his other friends were also booked.

He lives 90 mins away, so I said I wouldn't be there at the start...

I turned up and ONE other person had showed up.

Shameful.

 

[Martin Hocking]

Right as I said before thank you very much for all the advice it’s all very much appreciated.

Thankfully I’ve got a bit of help on Saturday my friend ‘gluten free’ will be on the barrow and my girlfriend on the rake with possible extra assistance from my neighbour. As long as I keep the mixer on the pipe we should be okay. I’m pretty sure I’ve mixed similar quantities at work but finishing it on my own too would be a different ball game altogether so I’m glad for the help.

My less than technical assessment is about 60 mixes out of a belle 140.

What’s causing me a little stress is ‘gluten free’ is only on about Saturday and wants to see the football so can’t go much past 4 so I need to be ready in the morning and I’ve got a bit of way to go…


Last of rubble to go in, then more fines to pack down, sand to blind off, pegs for shuttering, dpm, worlds cheapest (and partially eaten) blue insulation, more dpm, mesh in and wired ready for chairs. Loads of faff really, so I probably won’t be ready.

Which is why I wanted to know about splitting it up. I won’t unless I absolutely have to but it’s nice to have a bit of a plan b just in case. @Smallfry your suggestion seems the easiest to implement in a pinch so I’ll go with something like that I think.

Oh and I need to remember to finish my bull float at work tomorrow too…


I went with mix it yourself to save a bit of money which if it weren’t for a lot of jiggery pokery it wouldn’t be by a mile. The main benefit is that as mentioned I’m not in the “slurm”(love the terminology!) with a mixer truck backing up with nothing to pour it into.
In any case the 10 tonnes of sand on my driveway sort of means there’s no choosing now!

I need sleep.

 

[addjunkie]

A second mixer is good if doing it by hand.