Greenhouse foundations

[esrikandan]

I had a guy come over to quote for laying the foundations for my new greenhouse. With materials he reckoned about £600-£700. This is to create a 6" thick concrete base.

Which seems like a lot!

[Hazel at the Hill]

Eek! I'll say!!!

What's wrong with leveling the ground, laying slabs, bolting g/h to slabs?

[kernowyon]

use slabs or bricks/blocks (breeze blocks in wickes 89p each) keep the floor of the greenhouse as earth at least you can plant into it.

[esrikandan]

Well...that's what I had wanted to do - but the guy suggested that laying slabs on the ground would become uneven over time.

Now I don't know what to do, cos if the slabs go wonky, then the greenhouse may go wonky too. I have to say, I'm not keen on concrete either. not very environmental, plus a bit too permanent for my liking.

[kernowyon]

perhaps the guy was trying to persuade you to part with £600!!!!

another suggestion use railway sleepers

[bridget mc laughlin]

For mine I just layed down some concrete slabs and bolted it to them

[bobleponge]

The man from Kernow stole my line. Buy 4 sleepers, not sure about UK but at home about 15Euro a go. Get them down and level on a bed of soil and sand. Keeps inside as soil for planting or flags if you wish, and sleepers wont warp. And save yourself around 550 quid. Job done.
P.S. That will be be a bill for 550 pounds consultancy fee. Ta

[terrier]

Another way is to dig out the top soil, buy in enough hardcore from a builders yard to fill hole( 1 ton roughly equals 1 square meter) and hire a vibrating plate from a tool hire firm. Shovel hardcore into hole, compact it with vibrating plate (good fun). Build green house on top. A helluva lot cheaper than your quote.

[esrikandan]

The problem I have is that getting any equipment into my back garden is a challenge (middle of three houses) as things have to go through the house. Any my car is tiny, so any large materials would involve hiring a van. My original plan was to level the ground and lob some slabs on, but I wonder if I dig a small trench (say 6" or 8"), fill it with gravel, then some sand on top, and then put the greenhouse base on that?

[workhorse]

I have just had a greenhouse put up, and all that was done by my builder was to level the ground, and lay large paving slabs straight on to off the levelled soil. It worked a treat. Only cost £300, and that was for the lot.

[Paul Wagland]

Hi Esrikandan, what is your soil like? Is it nice and stable, or prone to shifting or flooding?

If you have good stable ground you can get away with a very light base (greenhouses aren't exactly heavy) - something like 50mm of compacted sand with paving slabs (or how about nice red bricks?) laid directly on top. You wouldn't even need mortar, just bed the paving into the sand with a rubber mallet.

On less stable ground you might be better to go for a concrete base - or at least use mortar under your paving. And perhaps a deeper footing, maybe 75mm hardcore plus the depth of the mortar and slabs/bricks.

Six inches (about 150mm) is way too much for a job like this, and even if it wasn't £600 would be too much to pay. I laid a 150mm patio base a couple of weeks back - it took two days work and about £80 in materials.

[Paul Wagland]

Another way is to dig out the top soil, buy in enough hardcore from a builders yard to fill hole( 1 ton roughly equals 1 square meter) and hire a vibrating plate from a tool hire firm. Shovel hardcore into hole, compact it with vibrating plate (good fun). Build green house on top. A helluva lot cheaper than your quote.

You mean one tonne is roughly one cubic meter I think Terrier?

Plate vibrators are great fun indeed, but for a small job you can also use an up-ended sledge hammer to 'tamp' the hardcore down.

[jools]

Hi Esrikandan, I had a paved base laid for my greenhouse just over a year ago and I'm very very pleased with it. When you water, the excess runs through the cracks in the slabs rather than pooling on the floor, as it would with concrete. I had earth beds in my last greenhouse and prefer having a solid base.

I managed to get some heavy paving slabs second hand - didn't have to pay much for them but had to go and pick them up. I have a couple of Czec guys who do all sorts of heavy gardening stuff for me and they laid my base. They put down some hard core and a layer of sand and then the slabs on top. They are realy great guys and I'm pretty sure they would cover your area (I'm in Staines). Also, they have always been happy to pick up materials for me as I pay them by the hour. If you are interested, PM me and I'll let you have their details.
Jools

[esrikandan]

My soil is fairly clay-like. So I'm guessing a patio-type base would suffice. I'm not keen on using concrete unless I really *have* too. I think the hard-core plus a layer of sand would be ok.

Besides, the Greenhouse was £350 - £600 for foundations seems like madness. Better doing a cheaper job and risk replacing the greenhouse.

Joools - will PM you.

Thanks all,

Eric

[loosecanon]

Re the Greenhouse base

Hi everyone

I have recently undertaken the erecting of a greenhouse of 6' by 4' dimensions but I have a tendency to over do things as will become clear no doubt.

The base, you see, is going to be situated on clay which frequently becomes bogged when it rains.

So, I thought it ought have concrete foundations to give it stability, so I set about digging out the top 5 or 6 inches to accommodate a suitable base. I then knocked up some formers to ensure the base was exactly square and set them to ensure that all sides were level and there would be no twist in the frame once it was mounted on the base.

The long and short of it is that I spent much of Friday mixing concrete by hand, which whilst I could have done with ease some years ago, very near killed me this time and I gave up before creating the nice level ridge that I had planned to sit the base on, so I had to start again yesterday, this time with the aid of a cement mixer.

Anyway I am now at a stage where I can mount the base frame on top of the concrete for which I have left a hole in each corner, the idea being to cement the legs so as to anchor the frame securely and resist the wind.

My point here is that if I had thought it through before diving in and creating a lot of work for myself, I would have simply dug a hole in each corner for sufficient concrete into which I could sink the legs and stabilise the frame and ensure it sits square and level. Once set I could level the interior with gravel and achieve good drainage into the bargain.

My plan was to keep the steel frame out of the inevitable puddles that accumulate and thereby ensuring long life for the greenhouse but in reality by producing a concrete base maybe all I have done is create a lot of work for nothing and maybe even create a problem of poor drainage - we'll have to wait and see, I'll let you know.

What I can say is there is often an easier solution and the first idea is not always the best

I would say have a cup of tea and think it through!