Some concrete advice

[bobleponge]

No, as usual, nothing helpful from me, but I'm looking for assistance.
I am taking delivery of a greenhouse in the next couple of weeks (thanks again SlugLobber) and I am aiming to put it on a concrete base in the garden.
The greenhouse is 4 x 3m approx, so:
How wide/long do I build the base, and perhaps most importantly, how deep?
Also, do I use aggregate or just sand and cement?

Many thanks in advance to all you building type peeps who can assist.

[zebedee]

No, as usual, nothing helpful from me, but I'm looking for assistance.
I am taking delivery of a greenhouse in the next couple of weeks (thanks again SlugLobber) and I am aiming to put it on a concrete base in the garden.
The greenhouse is 4 x 3m approx, so:
How wide/long do I build the base, and perhaps most importantly, how deep?
Also, do I use aggregate or just sand and cement?

Many thanks in advance to all you building type peeps who can assist.

You want the greenhouse to last a long time, so allow about 10cm all round for water to run off, dig your base with space for about 10cm hardcore and about 10cm concrete (aggregate, sand & cement). It should last a lifetime, mate. Happy digging!

[bobleponge]

Nice one mate, many thanks. I'll be out there this morning then, digging a nole

[Hilary B]

Make sure your base rises to a little higher than the surroundings (a couple of inches should do).
Are you completely sure you want a solid base, not just strip foundation under the walls?
Compact the hardcore well before adding concrete.

Depending on soil type (at the bottom of the hole) and whether there are trees or fast growing bushes nearby, extra depth might be necessary, although one advantage of a solid base is that it is less vulnerable to this sort of problem..

[bobleponge]

I would prefer a solid base. I am very lucky in that I have a decent sized garden, so the greenhouse will be used (along with my other smaller one) for starting stuff off and overwintering, I wont be growing anything in the soil.
Thanks for the compacting advice. There are no trees or fast growing shrubbery where I intend to the put the new structure, but as you said, the solid base will stop anything growing through it.

[Hilary B]

I would prefer a solid base. I am very lucky in that I have a decent sized garden, so the greenhouse will be used (along with my other smaller one) for starting stuff off and overwintering, I wont be growing anything in the soil.
Thanks for the compacting advice. There are no trees or fast growing shrubbery where I intend to the put the new structure, but as you said, the solid base will stop anything growing through it.

It isn't about things growing through. On some soils trees dry out the soil so that it shrinks. Strip foundations are often broken when that happens, but a solid foundation the size of that should remain whole regardless (if everything was properly compacted in the first place, if not, it may crack).

[HeyWayne]

We've plenty of rebar out in the warehouse if you really want to make sure it's solid?

[bobleponge]

Cheers for the offer big fella, but luckily I have managed to scrounge some from a mate here who had extra. Not sure how I could have got it into the Barchetta but would have tried.