Another question about BI and ply shuttering

[zappastix]

Hi

We are about to install ply shuttering for residential footings.

Is it normal practice NOT to back fill once the shuttering is in place.

We would like to remove the ply (10 8' x 4' sheets (cut of course))
after the concrete has cured.

Although the 18mm ply is braced - we were thinking of inserting
stakes from the
surrounding bank and wedged on to the shuttering.

Have you had this allowed before by BI's.

Or do you think the BI will want the ply trench to be back filled?

I ask because we do not want to dig it all out again to recover the ply!

Thanks in advance.

Stephen

 

[RedHerring2]

It doesn't matter whether the trench is backfilled behind the ply, or not. But, if it is backfilled prior, how will you prevent the ply from caving in to the footings with the pressure from the backfill.
If it's not backfilled prior you need to appreciate the power that concrete can exert sideways. So brace the shuttering against the existing trench walls with at least 50mmX50mm, at least every 1 meter, with bracing joined up along the ply. 75mmX 50mm is better.

This is assuming a normal strip footing, trench fill could be an entirely different matter.

Remember, it's almost impossible to recover a spillage of readymix. It will also throw your volumetric calculations way out, so you could be short.

Normally, any ply shuttering is left and forgotten.

 

[noseall]

Whenever we have shuttered a trench, we dig the ply into the trench bottom by a few inches.

Wedge 4"x 2" sprags across the ply walls internally at the same time lightly back filling on the other side every metre or so. These sprags can be pulled as the concrete goes in.

As stated do not underestimate the push of the concrete it will be immense.

Forget recovering the ply.

 

[r896neo]

There are few things more frightening than seeing your shuttering breaking open, i and many others i'm sure have seen pretty grim events in this vein. I watched in horror as a 15ft high engineered retaining wall with concrete filled cavity bust open during the fill, as nose says don't underestimate the push of wet concrete and don't underestimate how **** it will be trying to sort it out if it does go wrong.

 

[theoldun]

Hi

We are about to install ply shuttering for residential footings.

I ask because we do not want to dig it all out again to recover the ply!

Thanks in advance.

Stephen

Tell you what to do,
Drill 50mm hole in side and midddle of each sheet of ply.
When concrete is hard, stick hook and chain in hole.
Hire 3 ton digger, attach chain to jib and get your son to lift them out one at a time,
Don't worry if you get machine set, your local friendly farmer now knows where you live, and will soon pull you out.
oldun

 

[RedHerring2]

Tell you what to do,
Drill 50mm hole in side and midddle of each sheet of ply.
When concrete is hard, stick hook and chain in hole.
Hire 3 ton digger, attach chain to jib and get your son to lift them out one at a time,
Don't worry if you get machine set, your local friendly farmer now knows where you live, and will soon pull you out.
oldun

I never realised that sarcasm was contagious.

 

[zappastix]

Don't worry if you get machine set, your local friendly farmer now knows where you live, and will soon pull you out.

Don't worry RedHerring - we deserve it (well my son does).

 

[theoldun]

I never realised that sarcasm was contagious.

Was not meant to be sarcastic Mister. Just a normal site wind up, known as the craic.
Zipppy did not bite, at least he understands.
All joking aside Zippy, that is how we get shuttering and trench sheets out.
oldun