Concrete formwork - half grass half paving

[Dazzy50]

Hi all,

Planning a concrete base for a 10ft x 14ft shed. Two main questions:

1) The area takes up part of my lawn and goes up to my garden path. The formwork that I will create for the lawn side will be held in the ground with stakes. I obviously can't do that on the side that is next to the pavement. Is it OK to just butt up the formwork against the pavement using the sub-base that I will be laying in the formwork frame? 3 inches or so of compacted sub-base should be enough to hold it against the pavement side shouldn't it? I can't see how I would secure that side without ramming a hole through my garden path...

2) Does the top of the formwork necessarily need to sit completely flush with the top of the concrete? Does it affect the tamping down process and the final level of the concrete?

Thanks!

Daz

 

[theprinceofdarkness]

That is how you get it flat. The most importent thing I cannot fathom, the edge of your base will be against the path, so is it lower, higher, the same or do you have to take a slope off the path, so the new base is horizontal (almost!).
One point thinking about is that if you are barrowing along the path, put down some Viscerene, or hardboard/cardboard to stop cement getting on the path.
If your level will be higher then the path, :- Cut the board to the right profile (slope on path?) with an extra 1" in height, then bracket a bit of floor board/chipboard every 3' or so along it so when the main board is laid on its edge the other boards hold it vertical and the extra 1" hangs over the path edge and aligns the board with the path edge. Load the supporting boards with some weight to stop the main board leaning back. When the job is done fill in the 1" deep groove between the path and base.
Frank

 

[Dazzy50]

Thanks for your help Frank. The path gently slopes down the garden so the top of base will sit above the level of the path to stop any rainwater falling off the path into the base (and then into the shed). I'll try what you suggested when I create the formwork this weekend.

 

[Grant McKenzie]

In the past when I couldn't pin down a form I've put braces and just stuck weight on it. Your slab won't be too thick so it should be fine to do something similar. Good luck!