precast concrete base for shed

[masamune]

I have to demolish an old precast garage to allow for an extension. After giving thought to a few options I decided to go with a PvC shed. The shed requires 100mm thick concrete slab around 3000mm x 3000mm at the base.

Quotes received for preparing site and purring mixed concrete for this work ranged in the area of £700~900...

I worth if worth considering a precast slab or something alternative for the base and whether it would save costs or have the opposite effect?

 

[Ian H]

Hire a mixer and make your own for £150.

 

[^woody^]

There is no reason why it can't go on some 2x2 slabs

 

[masamune]

Hire a mixer and make your own for £150.

It is an option

But I have to do it right and cannot delay the rest of the project...

 

[masamune]

There is no reason why it can't go on some 2x2 slabs

The soil is compacted clay, wouldn't slabs start sinking partially over time without some sort of footing?

 

[Tigercubrider]

So a "precast " slab 3 metres square and 100mm thick?

How in God's name do you move that?

 

[r896neo]

Paving slabs installed on a decent base will probably outlast the shed. 75mm of hardcore and 50mm of screed.

However it may be cheaper to simply pour a slab with readymix. I have done plenty and it usually works out similar cost but the concrete is better. If you need to shift materials a long way concrete is definately better.

There is a reason there is no market for precast concrete shed bases, its technically impractical and prohibitively expensive.

 

[Ian H]

It is an option

But I have to do it right and cannot delay the rest of the project...

Make a frame from 4x1, pour the concrete, run a 4mtr length of wood along the top of the frame to level and its job done.

Stick some mesh in it if you like but I wouldn't bother.

R896neo is right about the ready mix, it would be quicker and cleaner and might even be cheaper than doing it yourself if you had to hire a mixer.

See the frame on this one?:

 

[vards01]

Ready mix is about £100/m3 depending on locality...........so for £100 (0.9m3) it just isn't worth messing around with a mixer, cement, aggregate, mess, hard work etc.... Some firms also offer chopped fibre addition to the mix, so may not require the steel mesh.

By ready mix I mean a volumetric mixer, not a drum mixer. You only pay for what is needed on the pour. Most firms will probably have a minimum call out fee though. Worth a call round the local firms.....

 

[masamune]

So a "precast " slab 3 metres square and 100mm thick?

How in God's name do you move that?

well, yeah. I didn't mean as one piece but smaller precast sections perhaps

 

[masamune]

Great advice everyone, I can see why precast will not work and sounds like readymix is the way to go!

Seems that some a few companies will do 1m3 as a minimum, only thing is I need to figure out how to have this poured at the back of the garden...

 

[Tigercubrider]

So you just mean a cast base, created in advance?

If you have side access it's easier.
If in a terrace you might have to wheel barrow it through the house so preparation would be the key with tarps and hardboard laid as protection

Barrow mix is where a truck with dry ingredients arrives and they mix on site.

 

[masamune]

So you just mean a cast base, created in advance?

If you have side access it's easier.
If in a terrace you might have to wheel barrow it through the house so preparation would be the key with tarps and hardboard laid as protection

Barrow mix is where a truck with dry ingredients arrives and they mix on site.

Yes I have a side alley, thank god for this