Levelling area for greenhouse, fill with clay and scraws?

boardtc

Our garden area has a bit of a slope and we are looking at shuttering a 2x3m area and filling with clay to make even and then installing https://www.ksbgarden.com/products/greenhouse-optima-6m-3m-x-2m-9-8ft-x-6-5ft?variant=40716697993423

We are digging out an adjacent area for a sun deck and my question can we fill the shuttered area for the greenhouse with the scraws or just clay?

The Continental Op

If you can put the extra effort into pouring a concrete strip foundation you'll eventually realise it was well worth it.

Just down at my mothers this weekend and the greenhouse I put on a concrete strip foundation about 40 years ago is still up and looking well.

I'm not talking anything too special just a 6 inch wide strip as deep as you can reasonably sink it. Then fill with whatever suits. It is nice to be able to grow stuff in the soil inside the greenhouse so some good soil might be good. Growing in the soil may mean you want a flag or poured concrete path down the middle.

blackbox

The scraws will be fine for growing stuff in when they break down, but they are not suitable for supporting a structure.

boardtc

https://www.boards.ie/discussion/comment/119199723#Comment_119199723

Superb. thanks for the story. So thanks @blackbox's tip I won't use the scraws but will need to get 2 tons of clay to build up the 2x3m shuttered area and make flat, you are probably talking about 25-30cm difference.

@The Continental Op I'm unsure how the strip foundation would work when leveling the area?

magicbastarder

i had never heard the term 'scraw' before, had to look it up!

The Continental Op

Just shutter off a 6-8inch wide strip and fill with concrete, on the low side go as deep as you need to to get the level up all around.

So you may end up with a foot deep at the high end and 2 or more feet at the low end.

The Continental Op

https://www.boards.ie/discussion/comment/119200266#Comment_119200266

There are loads of weird and wonderful gardening terms we should make a list of them sometime.

looksee

I checked it up and google insisted i meant 'screws', I persisted and found it was a scottish/irish term for a piece of turf. So presumably the OP was taking about throwing in grass sods?

It took me years to get round the idea that ditches were convex in Ireland, rather than concave, now it is a natural idea!

monseiur

What is the approx gradient of the slope ? Could you perhaps build it up with 4'' blocks on flat to the floor level of greenhouse ? You could start with the first rows of blocks wider and gradually step every row in as you raise up. It's best not to put a concrete floor in greenhouse, just a narrow strip foundation to carry weight of frame. Fill with loose black type subsoil, the type that does not cake or harden like concrete ! and top off with minimium of 20'' of top quality top soil.

Regarding the word 'scraw' - it's the top 7 to 9'' layer on a bog, where the plant roots are, this is removed before cutting the turf. When cutting turf by hand years ago it was common practice to place this scraw down neatly where the previous years bank was cut, the scraw would grow back, as the plants & roots were intact, and over a number of years the cut bog would return to normal and regenerate.

boardtc

https://www.boards.ie/discussion/comment/119200268#Comment_119200268

Interesting. I had been thinking of leveling with a couple of tons of soil rather than digging out. It's very rocky ground so removing the soil leads to breaking up rocks. A couple of feet at the back would mean stacking 4 sleepers (100mx400m) for retention!

Girl Geraldine

For a greenhouse you need to have it on a proper reinforced concrete footing with the base of it at least 45cm below ground level.

I can tell you, building it as you suggest will just end with panes of glass randomly shattering all over the place as the thing settles.

boardtc

https://www.boards.ie/discussion/comment/119200520#Comment_119200520

Interesting, that's deeper than I would have thought, thanks for that. We are looking at polycarbonate https://www.ksbgarden.com/products/greenhouse-optima-6m-3m-x-2m-9-8ft-x-6-5ft?variant=40716697993423

The Continental Op

https://www.boards.ie/discussion/comment/119200520#Comment_119200520

But the link in the OP's OP isn't to a glass greenhouse ;-) It just needs something as an anchor to stop it blowing away.

The Continental Op

https://www.boards.ie/discussion/comment/119200502#Comment_119200502

You can use proper sleepers as a base they won't blow away. Just level then up and infill.

boardtc

https://www.boards.ie/discussion/comment/119200949#Comment_119200949

I'm intrigued but have questions? What is considered proper sleepers? I was looking at using them for back wall retention how do you mean for the base?

looksee

Proper sleepers are those ones that have actually been used on railways, thoroughly soaked in tar and will last forever. Nowadays its 'more or less the right size treated timber'. The real ones are not considered suitable for places where they will be in contact with food plants.

The Continental Op

Yep thats what I meant the old creosote soaked ones not the modern clean looking ones that only last a couple of years.

Last time I bought a real sleeper it was €40 eeeeek

Lumen

It sounds like the project is more like:

- build low retaining wall with cut and fill to create two level areas

- place greenhouse on upper terrace

- lay patio on lower terrace

Is that it?

Consider a mini digger. Every time I dig by hand I regret it.

boardtc

https://www.boards.ie/discussion/comment/119204822#Comment_119204822

Access at the back of our house is awkward for a mini digger but might have been manageable for this point in the garden. We have a few projects, the main patio is at the back of the house outside the back door (wrong aspect) but we are building a sun deck and adjacent greenhouse at the back of the garden in conjunction. I have someone working on it actually and he has put 2 days manually clearing the sun deck area, very rocky area so yesterday was working with a breaker. He mentioned the retaining wall idea at the end of the day yesterday too. I wish I had posted earlier, it would have been a better solution. Still have to do the section for greenhouse.

boardtc

https://www.boards.ie/discussion/comment/119202586#Comment_119202586

I found these ones I'm going to got for €45 https://landmarkarchitectural.ie/railway-sleepers/543/Azobe-Hardwood-Reclaimed-Sleepers

boardtc

https://www.boards.ie/discussion/comment/119200472#Comment_119200472

Interesting, i'd like to find out more abut this loose black type subsoil!

SOPHIE THE DOG

https://www.boards.ie/discussion/comment/119205410#Comment_119205410

Good choice on those sleepers (the tar/creosote treated ones will stink to high heaven inside a hot greenhouse).

A concrete base strip around the perimeter that the greenhouse can be firmly bolted down to is really the best way to go.

This is how mine was done and it has worked out well (I know you have a level challenge to face up to that i didn't).

monseiur

https://www.boards.ie/discussion/comment/119205520#Comment_119205520

You normally find this type of sub soil where there is black laomy top soil, it's the layer just under the top soil. It has loads of organic matter in it, loose stones etc. It is found mostly in peaty type land, near bogs etc. after all that's where peat moss comes from, it's loved by gardeners for a reason. Even when dried out it does not go rock solid like brown soil - (the one that's sticky, plasticy when wet). The advantage of the black stuff is that it allows the top soil above it to drain and breath something that's very important especially in a greenhouse senario.

looksee

How is it not also, or a continuation of, topsoil?