Shuttering for enclosed site - concrete raft / slab

[helvellyn950m]

Hi all,

I'm documenting my garage build over on this build thread, but I'm after a second opinion on how best to set up shuttering for my concrete pour that's coming next week.

I've built concrete slabs and poured driveways before. They've always stood proud of the ground, so the shuttering went on top, with stakes driven behind the planks / roadform.

This one is a little different, as two sides of the slab go up against the concrete fence, and the concrete raft is mostly below ground.

These pics will help explain (the camera makes things look much shallower!):

IMG_20200515_085411

• helvellyn950m
• 15 May 2020

IMG_20200515_085405

• helvellyn950m
• 15 May 2020

IMG_20200515_085417

• helvellyn950m
• 15 May 2020

IMG_20200514_222138

• helvellyn950m
• 15 May 2020

IMG_20200514_221613

• helvellyn950m
• 15 May 2020

IMG_20200514_221546

• helvellyn950m
• 15 May 2020

As I see it, my options for the sides with the fence are:

Option 1) To build tall "sides" to the shuttering out of ply or similar. These run from the bottom of the raft side at the deepest point, to the top edge. I stake them vertical, probably needing to knock in some sacrificial stakes on the inside that will end up under the concrete. I could backfill behind the ply with earth to keep it secure.

Option 2) Let the trenches and DPM contain the concrete at the bottom, no shuttering. I run a perimeter of planks along the upper edge, to give me a straight level top to level against.

Am I along the right lines, or are there better options?

Thanks in advance!

 

[kingandy2nd]

Are they your fences? I'd be inclined to remove them as I imagine they'll be redundant once the garage is built.

Also I'd not want the fence post concrete attached to the new slab as you're leaving yourself a future problem there.

 

[helvellyn950m]

Are they your fences? I'd be inclined to remove them as I imagine they'll be redundant once the garage is built.

Shared with neighbours on both sides, one house is going through probate at the moment. It had definitely crossed my mind, but there's a bit of hassle there and a £250 skip, but I only gain a few inches. The ground on the other side of each is concrete too.

Also I'd not want the fence post concrete attached to the new slab as you're leaving yourself a future problem there.

That's a good shout, noted. Thank you!

 

[kingandy2nd]

Shared with neighbours on both sides, one house is going through probate at the moment. It had definitely crossed my mind, but there's a bit of hassle there and a £250 skip, but I only gain a few inches. The ground on the other side of each is concrete too.



That's a good shout, noted. Thank you!

It’s not about gaining the land, more the easy (or not) of access to do anything to the walls of your garage once built.

Likewise, concrete posts don’t last forever and they don’t look all that new/nice now. Just think how tricky it would be to maintain or replace the fence and posts once your garage is built.

As for the cost of the skip, there’s value in those gravel boards, or at the very least someone will take them on free cycle. Same with the posts, cut them near ground level and someone will have them for a 3/4ft fence

The rest can go to the tip in the boot of your car for the cost of your time.

 

[helvellyn950m]

Thanks Andy, that's some good thinking. Of course it's not all my decision, there are two neighbors to consult with too. I'll see what I can negotiate!

In the meantime, I'll need to make a decision on the shuttering!