What to use for shuttering.

[DIYalot]

There is a wall at the end of my garden. Put up by the Council years ago. It's length is 7.2m. The concrete foundation is quite shallow, about 150mm. It's clear that no shuttering was used, because the edge of the concrete is rather ragged and it does not have a flat bottom to it.

Okay, so, what I want to do, is "tidy up" the foundation on my garden side (other side is public pavement), by making a straight edge and trying to make a flat bottom to the foundation on the garden side at least. I'll probably slightly increase the height of the foundation until it is level with the garden topsoil. Then I'll have a concrete band, about 150mm wide, from the wall surface to the start of the grass.

Now, my idea was to do the work in two stages, that is put shuttering in from one end to over half way. Then, pour in the concrete up to half way the length of the wall, but putting in a strong metal bar at the end near the middle. Then, when set, putting the shuttering in from the other end and pouring in concrete. The metal bar "interlocking" the two halves. This way, the idea is that I don't need to buy shuttering to go from one end of the wall to the other.

Now, as to the shuttering itself. I was going to try to buy cheap scaffold boards, but I've not yet managed to source some locally. So, I'm thinking of buying timber gravel board 19mm x 150mm x 2400mm from Wickes at £5.05.

So far that Wickes gravel board appears to be my best option for shuttering. I hope it is alright to use. I've no better idea.

 

[tomfe]

Just some 18mm ply will do it, make sure you put plenty of stakes in and bracing.

 

[Bilabong007]

I don't get what you mean about a "flat bottom" of a foundation. Surely that's the bit in the ground?

 

[DIYalot]

It looks like the original trench is a V shape rather than a U shape. Making the foundation thinner at the edges. I'll be trying to make the foundation a constant thickness on my side, the garden side.

18mm plywood is okay - okay. But, I'm trying to cut my costs by using these Wickes timber gravel boards. I imagine they would be ok, but seeking some input on that. Rich

 

[tomfe]

A sheet of ply is £25 you'd get 8 lengths of 2.4m x 150mm. That would cost £40 in gravel boards, ply will leave a nicer finish and is stronger.
I am not completely sure what you are trying to achieve with recreating a foundation, sounds like you are just shuttering off a bit of concrete to make it flat. You should not have dug under the existing foundation as you have now weakened it.
But I think you've already made your mind up with what you are doing.

 

[DIYalot]

Here are two pictures. A general view of the wall (which is 70cm high). And a picture detailing the foundation. I've just messed with a small section, as an exploratory investigation. Really, I'm just wanting to tidy up the foundation on my side. Of course, I don't want to end up weakening the foundation so it begins to slowly keel over into my garden.

 

[rssteve]

It appears you have removed soil since the foundation was poured. Simply add some soil against the wall.

 

[Ian H]

I'd knock the overhangs off with a bolster and trowel some concrete up against what's left. Then bury it.

 

[Nozzle]

Take a 9" angle grinder to it.

Nozzle

 

[DIYalot]

What I'm minded to do, is remove the "over-hang" for half the distance of the length of the wall, that would be 3.6m. If the foundation is 6" thick just below the wall, then I would see the wall sitting on that 6" of foundation. In that 3.6m section, I'm minded to remove dirt to a depth of the current foundation out to a distance of 6" from the wall surface. Of course I'd put shuttering parallel to the wall and 6" from the wall. Then I'd fill in the 6" x 6" x 3.6m trench with concrete. Of course, that section has wall either side of it. It won't be a situation where any section terminates in and end of wall. So, there will be support on either end of the section. Now, safety is an issue of course. On that score I would think that this rather small wall would not budge at all during the time the trench is unfilled. And won't move after the concrete sets. Precisely because the wall is presenting no significant forces. It may be wise, to support the wall from halfway along the section, however, as I say, I'd not think the wall is going to move for the time the trench is unfilled, which could be say an hour or so. I welcome any comment on the safety issue and the long term stability of the wall after the proposed intervention. Thanks. Wall is over 50 years old. Rich

 

[Doggit]

I suspect if you dug down a bit further, you'd find the foundation under the wall to be oaky, so shouldn't need supporting whilst you work. All you're doing is tidying up the footings, so as you say, you just need to go down about 6". On that basis, you just need strips of shuttering 8" wide, and for what you're doing, even 9mm thick and backfilled behind it would be fine, but if you want to do this on the cheap, maybe look for a couple of 15mm melamine faced boards like these, and do it in 2.4m sections instead.

 

[Adam182]

The gravel boards would be fine to use, just make sure to back up the shutter with soil and wooden stakes to stop it flexing from the weight of the concrete. At the depth were talking though the amount of weight behind isn't going to be much.

 

[DIYalot]

If I used 2.44 m lengths of shuttering, then I'd need to pour concrete on 3 separate occasions. I think in principle that is okay. Would I need to lay in a metal bar at each of the section interfaces (of which there would be 2) to "lock" one section to another? Rich

 

[Ian H]

I'm struggling to see why you want to tidy up a 50 year old foundation that's buried.

By leaving it as it is your budget would be £0.00

 

[DIYalot]

I'm struggling to see why you want to tidy up a 50 year old foundation that's buried.

By leaving it as it is your budget would be £0.00

Well, I have a certain mindset. For instance, I've just dug up 1/3 of the garden for the purpose of removing all the crud left behind by the builders. There were tiles, concrete aggregates, bricks and a cement layer no doubt where the cement mixing had taken place. I just had to cleanse the garden. It bugs me that all that crud is just under the surface of my garden. Similarly with this wall, it bugs me that the foundation is not straight. And besides, my plan was to bring up the foundation to the level of the garden, to produce a 6" wide band adjacent to the wall. Such people as me exist.