[Closed] Greenhouse bases ?

https://www.growfruitandveg.co.uk/grapevine/forum/on-the-plot/undercover-operations

I leveled the area as best I could. Laid a weed barrier, and put down plastic shed base sections which were slightly larger than the green house, filled with gravel. Then cut four bits of  cured timber for the frame of the green house to sit on and put them on top.

Got the timber frame sections as level as I could before building the green house on top and screwed all the timber together with galvanised 90° brackets and the base to the green house last of all after about 24 hrs after putting the glass in. I used the plastic base sections gives It a nice level surface inside and I put down a few concrete slabs we had.lying around down the middle.

Shed base drains well and should keep standing water off the timber, but they are also easy to replace if they rot out. Took a weekend to so to do - a day for the base and a day to (re)build the green house which was relocated from another house.

But if you want long lasting concrete is the way to go - but you should still mount the greenhouse on timber.

Our greenhouse is about 2m x 4m and aluminium, and a quality one.

I put in concrete footings and then mortared in a single (dwarf) row of driveway bricks (no holes). All very plumb.

I then bolted the greenhouse down as we built it.

The inside was dug out, 'sealed' with thick black plastic and then graded with sand/cement. 600x600 pavers were then laid on top.

I only intended to do it once 🙂

But if you want long lasting concrete is the way to go – but you should still mount the greenhouse on timber.

Why would you put down something that will rot?

For ours I laid a perimeter concrete foundation about 6-8 inches thick. We're in an exposed location and on a slope so i wanted something solid to bolt the frame too. Inside I levelled the dirt, laid some weed membrane, put a strip of old slabs down the middle as a pathway and filled each side of that with pea shingle. It works well!

Our ground slopes in both directions.  I dug and concreted some footings for a single course block wall and bolted the frame to the top of it.  Because of the slope, at the the front, the top of the block wall is just above ground level.  At the rear, the whole course are is above ground.  I levelled the earth in the middle, laid a bed for a paving stone path up the middle.  Either side of the path was covered with a weed barrier then ornamental gravel.  Done during the first lock down.  I might have over engineered the foundations, but I had fun and learned some stuff! I even roped the Mrs in as a builders labourer. It looks great, a pleasing project.

Thanks guys
@blokeuptheroad that is an excellent job, may shamelessly copy that approach.

I’m curious why mount the greenhouse on timber ? Surely that will rot over time. I hadn’t planned on using any wood for this.

I’m not the gardener who will be using this - so this may be obvious to a gardener type, but why is nothing planted in the ground in a greenhouse?

I was about to pitch in with a long explanation of how I did the bases for two sheds. It’s pretty much how @blokeuptheroad did it.

Except he’s done a far better job. I didn’t pour proper footings. I dug trenches, then a 4” layer of scalpings, stamped down, then the concrete blocks on a concrete mix using just sharp sand. Normal laying mix between the blocks, then when set a mix of whatever was left either side of the blocks to encase them a bit, but still under the soil level.

Actually that ended up as a long winded explanation. Just do it like up there. ^^^^^^^^^^
🙂

I’m not the gardener who will be using this – so this may be obvious to a gardener type, but why is nothing planted in the ground in a greenhouse?

I'm not the gardener either, just groundsman/dogsbody so the following guess at an answer could be nonsense. I suppose you could plant in the ground, but unless your are growing lots of the same thing it's more convenient to have stuff in pots. We are (well, the Mrs is ) experimenting with lots of different varieties of chillies, peppers, tomatoes etc. these work well in pots so you can move them round or change over what you're growing if stuff doesn't do well. It's also really handy to have the smaller pots on the staging (shelves) so you have to do less bending over for watering etc.  In ours, the base is free draining under the gravel and weed mat so there is no issue watering everything with a hose.

I’m curious why mount the greenhouse on timber ? Surely that will rot over time. I hadn’t planned on using any wood for this.

Not sure either.  The instructions for ours (Rhino brand) said to erect it straight on level earth, slabs or on a dwarf wall as we've done.  I've got a few treated timber structures in the garden and they all rot at ground level after a few years.  Like you I wanted a construction method which will last and require minimum maintenance.

Concrete is responsible for 8% of greenhouse gases, and 70% of greenhouse bases.

I’m not the gardener who will be using this – so this may be obvious to a gardener type, but why is nothing planted in the ground in a greenhouse?

Also not a gardener, but I'd suggest that most things grown in greenhouses are either relatively short-lived or get moved outside once established - either way, growing in pots keeps the roots contained.

I suspect whilst greenhouses tend to see higher air temperatures than outside, the ground temperature is fairly consistent with outside. If trying to germinate seeds or whatever, the high air temperature (and direct sunlight) will more easily warm the volume of soil air in a pot than it will the entire base of the greenhouse (which will then tend to leech out into the rest of the garden).

Don't know about greenhouse bases but generally you don't plant in the ground in a greenhouse as you'd then have to be fairly strict with crop rotation and often you want to plant similar crops in the greenhouse every year (mainly tomatoes and cucumbers for us once the seedlings of other stuff move outside). There isn't much point growing beans or most greens inside unless you are trying to get early or late season crops.
With larger poly tunnels people sometimes use raised beds and rotate crops but the greater space allows that luxury.
Greenhouse can also be bad for pests and mould infections so it's useful to just clear out and scrub it down every spring.
That's my understanding and may be wrong but works for an amateur like me.
And that greenhouse up there ^^^ looks fantastic. Far better organised that mine ever is. Hope you all get lots of good crops and flowers.

I was told that the floor had to be level and with zero ability for weeds etc to come through, which is why I did my usual Isambard approach.

Why use a 2x2 when a 4x4 will do the same job.
Why use a 6" footing when a 12" footing could be used.

As for timber - we rent so the green house and base will be removed at some point. I guess I was just thinking about our situation.