Laying concrete and shuttering for greenhouse

[purpleroad]

A bit dark so not clear but basically need to lay trenches a shovels width around perimeter of green house and use shuttering to keep it level. Going to put greenhouse base (those silver things in photo) onto concrete so it's level. Never done it before. Is it easy or best to get landscaper friend to help me?

 

[Notch7]

I think your first problem is you need to work in the daytime

 

[purpleroad]

Haha.

Is it case of digging a spades width apart, using the shuttering pegs and a big level or piece of wood and level to check they're the same height. Then check the diagonals are the same distance so I know it's exactly rectangular? Then put in base of green house

 

[Notch7]

Haha.

Is it case of digging a spades width apart, using the shuttering pegs and a big level or piece of wood and level to check they're the same height. Then check the diagonals are the same distance so I know it's exactly rectangular? Then put in base of green house

If you wanting a level trench foundation, then yes I guess you need to shutter off the top to get an even flat perimeter to build on.

You really need to dig down a bit, at least below the top soil. The shuttering only needs to be at the top though.

I think greenhouses are often just laid on concrete blocks or kerbstones. I seem to remember years ago Alton greenhouses suppled shaped kerbstones.

Much drpends on the ground and if there are loads of trees around. If theres a lot of soil movement a thin perimeter foundation might crack and move.

 

[JohnD]

the shuttering doesn't have to line the entire trench, but the top few inches at, and just below, ground level will be enough for you to strike it off level, and not to look a horrible mess. Shutter it deep enough for any part that might later be exposed when gardening.

 

[purpleroad]

And are the pegs in the middle of the trench in the four corners and the tops of these all level with each other and the level which the concrete is poured?

I was just going to cut up some ply for the shuttering. Dig a four inch deep hole and bang in four pegs which are level with each other and perfectly square to each other.

Someone said about keeping the concrete tidy, does that mean keeping it contained in the holes and not having it spilling over?

 

[JohnD]

IMO if you're shuttering, the pegs are superfluous. you will be putting your spirit level along and across the boards to check the tops of your shuttering are all level. You presumably aren't using a laser or theodolite.

Keep checking as you pour, wet mix is heavy and they might shift.

Use ply if you have it handy. I've taken to using decking boards which are cheap and readily available (and mostly fairly straight)

 

[purpleroad]

IMO if you're shuttering, the pegs are superfluous. you will be putting your spirit level along and across the boards to check the tops of your shuttering are all level. You presumably aren't using a laser or theodolite.

Keep checking as you pour, wet mix is heavy and they might shift.

Use ply if you have it handy. I've taken to using decking boards which are cheap and readily available (and mostly fairly straight)

What mix would you use? Ballast and 4 to 1

 

[JohnD]

that sounds too rich to me. More like 1:6. try http://www.diydoctor.org.uk/projects/mixing_concrete.htm

Most important is to avoid frost for the first few days. Mix and pour at 10C or higher (you can mix using hot water in winter) and cover well, to protect from the cold and to prevent it drying out. If you can keep it damp for a month that will enable it to cure hard and strong (at this of the year, shouldn't be difficult). you can shovel sand or soil over it for protection, once it has passed initial set. Lay plastic first to keep it clean.