concrete garage bases

helpimcrap

helpimcrap

helpimcrap

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Hi peeps,
How much for a concrete base for a concrete garage - base needs to be 9'1" x 17'3".
I'm toying with the idea of doing it myself but have got up to a material cost of £700 so far!!!

I need to -
Dig up Tarmac 10" deep, then 4" Hard core, then 6" concrete mix with wire mesh in to stop it cracking under weight.
Is that about right?

I've enquired about getting it done and am waiting on things to happen but after an idea of cost if i get it done please?
 
Are you going to mix your own concrete of get a ready mix delivery? (Have you factored in mixer hire/purchase?)

Good luck! Go for it!

But do not underestimate just how hard physical work this is likely to be!

If you haven't done something like this before it will shock you!
 
Thought about digging the base up and allowed for 2 skip loads - toying with the idea of ready mix delivery but factored price on buying the cement and sand and mixing it myself in a wheelbarrow - worst case scenario so to speak!
 
Have you factored in time to mix, chances of uneven mixes making weak spots, how many mixer loads you would need to mix etc? If it needs to last a lot of years, i would go for a readymix.
 
mixing it myself in a wheelbarrow - worst case scenario
Click to expand...

Yes it is! Don't even think about it! :D

Rough ball par figure , (Given your dimensions and assuming around 2000Kg/Me3) You will be needing around 5 Tons of concrete!

If you try to do this in a wheel barrow/Bucket/etc you will likely...

a) Kill yourself!
b) Not produce it fast enough to get a decent pour. (So the base will have weakness and flaws)
c) Kill your self!
d) All of the above!
e) Kill yourself!

Do you see where I am going with this...:D

(Mind, I dont know how much help you are hoping to get with this)

Personally, especially if I was on my own, I would do the preparation myself but get a ready-mix delivery for the actual pour. You will need significant help and a mixer to mix the concrete yourself!
 
Readymix.

Don't even think about mixing it yourself, a cubic meter of concrete weights about 2.5 tonne (2500 Kgs), that's roughly 50 barrows, based on 50kg per barrow.

Prepare the base,digging out out shuttering, etc, even with readymix you will need two people to laid & tamp it.

Your looking at 150mm type 1 for subase,well compacted & 150mm concrete reinforced with A142 mesh.
 
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I've done it with a cement mixer (unfortunately not a tipping version), and as it was just a subfloor I did it over several weekends and it turned out OK. Wheelbarrow mixes are for fence posts, nothing more.
For a garage it's probably not worth it, get it poured in. Make a decent job of the shuttering, concrete is heavier than you think.
 
I laid a concrete hard standing here, & even though I have 150ltr contractor concrete mixer, using readymix was far easy, poured, tamped & laid in about a hour.

It is ****** hard work mixing enough concrete for a garage base 150mm, if your not use to doing it YOU WILL struggle.
Having ReadyMix, you get a perfectly consistent mix, & the right grade for the job.
 
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Nightglow said:
Readymix.

Don't even think about mixing it yourself, a cubic meter of concrete weights about 2.5 tonne (2500 Kgs), that's roughly 50 barrows, based on 50kg per barrow.

Prepare the base,digging out out shuttering, etc, even with readymix you will need two people to laid & tamp it.
Click to expand...

Indeed, even with ready-mix, you will still need to organise help!

Depending on the weather you will only have 1-2 hours to make things good even with ready-mix you only have a relatively small window! (Aim for less than an hour for the pour)
 
You can get concrete firm to add a retarder to the readymix, will give you a bit more time.

Best to get shuttering & everything ready for the pour the day before, & as already mention, make sure shuttering is well pegged. pegs need to be in the ground at least 400mm.
And you will nee a length of 5x2 for tamping concrete.

Your looking at around 2.2 cubic metres of concrete, price depends on area, but around £220-£300.

Make sure your subase is 300mm wider than concrete base all the way round.
 
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cheers for the insights guys - but how much should one expect to pay to have a base put in?

People say about shuttering - what actually is that!?

Is it like putting stakes in the ground to stop the outer edge of tarmac falling into the hole?
 
Shuttering is 150mm x25mm sawn timber & held in place with 50mmx50mm sawn timber pegs.

As I said in eariler reply, laid your subase up to 300mm wider on all sides than your concrete base, when you laid shuttering, check the squareness by measuring the diagonals.

you need to make sure you use enough pegs with shuttering, otherwise the concrete will break out when you pour the concrete.

If your having a ramp to garage, pour this seperate a few days after doing garage base.
 
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Nightglow said:
150mm x25mm sawn timber * 50mmx50mm sawn timber pegs.

As I said in eariler reply, laid your subase 300mm wider on all sides than your concrete base, when you laid shuttering, check the squareness by measuring the diagonals.

you need to make sure you use enough pegs with shuttering, otherwise the concrete will break out when you pour the concrete.

If your having a ramp to garage, pour this seperate a few days after doing garage base.
Click to expand...

Yep 6" wider than the garage on all sides using mesh in the concrete to stop it breaking up.

laid shuttering?
Is it plastic sheet or something?

No ramp.

I was just going to dig a hole 10" deep and fill with hard core/concrete and then let dry. Then garage on top.
 
PhillyDee said:
http://www.bing.com/images/search?q...A3022E1EF5F54E40AAB69DABB5BE&selectedIndex=49

Is shuttering. It will give you perfect smooth sides and be a much much better job. You can also get an exact amount of concrete to fill it. As said, it needs to be quite well supported / pegged out.
Click to expand...

Ah shuttering is basically breezeblock or equivilent around the edge of the hole a) stopping the tarmac falling in and b) giving a nice square hole which will hold the concrete in as well.

Thanks for that!
 
I would use A252 mesh as a minimum. The code requirements are generally 0.13% Aconc for flexural members and a 150mm thick slab requires 195mm2/m width > A142.

A252 uses 8mm wire at 200mm grid. Allow 300m lap to end and sides of sheets onto adjacent sheet (2400mm x 1200mm) to get quantity. The lap allows for transfer of stress across the sheet.

Allow 30mm to 40mm cover from the top of the concrete slab for the mesh. This can be fixed beforehand on stools from the subbase or trod into the top of the wet concrete before tamping. Most garage slabs are loaded at the edges by the walls and wheel loads. This means that the top of the slab is in tension hence the need for steel to prevent cracking. If unsure about the subbase for settlements or for very heavy vehicles, a layer of mesh in the bottom should be included.

A layer of heavy duty plastic sheet (visqueen) under the concrete will prevent loss of fines into the ground and provide some damp proofing.

Shuttering will be used for tamping the wet concrete and a length of timber just longer than the width of the slab is best to do this. Nailing a couple of uprights and handles at the end of the tamp will make the job easier. Float finish the edges of the slab to provide a suitable flat surface for wall construction or a damp proofing membrane. A slight fall from back to front of the slab will avoid water ponding on the slab when washing down or during heavy rain if it gets under the door. This can be set up by sloping the shutters slightly.
 
nkata said:
I would use A252 mesh as a minimum. The code requirements are generally 0.13% Aconc for flexural members and a 150mm thick slab requires 195mm2/m width > A142.

A252 uses 8mm wire at 200mm grid. Allow 300m lap to end and sides of sheets onto adjacent sheet (2400mm x 1200mm) to get quantity. The lap allows for transfer of stress across the sheet.

Allow 30mm to 40mm cover from the top of the concrete slab for the mesh. This can be fixed beforehand on stools from the subbase or trod into the top of the wet concrete before tamping. Most garage slabs are loaded at the edges by the walls and wheel loads. This means that the top of the slab is in tension hence the need for steel to prevent cracking. If unsure about the subbase for settlements or for very heavy vehicles, a layer of mesh in the bottom should be included.

A layer of heavy duty plastic sheet (visqueen) under the concrete will prevent loss of fines into the ground and provide some damp proofing.

Shuttering will be used for tamping the wet concrete and a length of timber just longer than the width of the slab is best to do this. Nailing a couple of uprights and handles at the end of the tamp will make the job easier. Float finish the edges of the slab to provide a suitable flat surface for wall construction or a damp proofing membrane. A slight fall from back to front of the slab will avoid water ponding on the slab when washing down or during heavy rain if it gets under the door. This can be set up by sloping the shutters slightly.
Click to expand...

There is quite a difference in prices between A142 & A252 mesh, 4800 x 2400 sheets for A142 £35.80 & A252 £63.70 approx prices plus vat.

But,you could instead use A193 mesh (7mm wire) £48.71p which would be suitable for all concrete up to around 200mm.
Also the minimum preferred covering of concrete is 50mm, not 30mm-40mm, & shuttering is formwork usually timber for retaining the concrete.
Prefer to use a length of 4x2 for a Tamping beam, having handles is opitional, I prefer without myself.
And I certianly wouldn't laid a concrete garage base with a fall, if it's for a erected prefab building as it will be sloping as well.
 
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Nightglow said:
There is quite a difference in prices between A142 & A252 mesh, 4800 x 2400 sheets for A142 £35.80 & A252 £63.70 approx prices plus vat.

But,you could instead use A193 mesh (7mm wire) £48.71p which would be suitable for all concrete up to around 200mm.
Also the minimum preferred covering of concrete is 50mm, not 30mm-40mm, & shuttering is formwork usually timber for retaining the concrete.
Prefer to use a length of 4x2 for a Tamping beam, having handles is opitional, I prefer without myself.
And I certianly wouldn't laid a concrete garage base with a fall, if it's for a erected prefab building as it will be sloping as well.
Click to expand...

A193 is suitable, 30-50mm is also suitable cover, is only approximate for this scale of project. I badly explained shuttering, yes it is to retain concrete, you can hire simple steel forms for slab edges with steel spikes to drive into the ground (roadforms) may be cheaper than buying timber (I used to be formwork/temporary works designer for several major contractors in a previous life).
Formwork needs to be robust enough to use to tamp the concrete surface from, which was my point..

A fall of 5-10mm per metre is useful and would in my opinion be perfectly acceptable in a sectional concrete structure.
 
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Got a quote on the gargae base. Want to get another to compare.

£860 which is digging it up, prepping it, and sticking 4" hard core and 4" of fibres concrete mix and it includes the waterproof membrane and wire mesh in the concrete.

Does this sound a good price?

It's going to cost about £2-300 for skips, £400 for the readymix cement, £100 for mesh and about £20 for membrane.

It works out I'll be paying all that anyway if i did it myself....

The garage company recommend a 4" hard core/4" concrete base (but this includes concrete fibre mix and mesh).
 
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