Extension dpc height

[23vc]

Thanks v much guys that's an eye opener and I'll discuss options with the bco. For now though regardless I think I'm good to pour concrete footings to 450mm below desired ffl?

 

[noseall]

For now though regardless I think I'm good to pour concrete footings to 450mm below desired ffl?

The concrete level needs to coincide with whatever masonry increments you are going to build with below DPC. You would typically work in 75mm/225mm increments.

You also need to consider external ground levels and external drain gully locations when deciding upon a suitable (maximum height) foundation concrete level. You are better off in terms of economy to pour as much concrete in as possible without effecting gully positions, drain runs or risk showing any concrete above ground.

In most cases we opt for two courses of block and one final topper of brick for the inner leaf and one block and four courses of brick for the outer leaf. This equates to 525mm below DPC to foundation concrete top.
Having that final course of bricks on the inner leaf means you can easily remove them when screeding into the external opening reveals.

 

[23vc]

Thanks noseall, yeah I know you do 7 courses as I've learned a lot from your posts on here. I'm unlikely to have a screed so will stick with 6 courses. Yeah I've got some drains to run across over the top of the pour, and some gullies, so I won't pour any higher. Thanks again I really appreciate the response.
John

 

[23vc]

All pegged out and ready to pour in the morning despite Doris's efforts! Thanks to all for the advice as ever
Last question if anyone's still reading this, I've put osb in places to stop the sides collapsing, braced with a bit of 4x2 etc, is this OK to leave in place and trim down at a later date?
Cheers
John

 

[noseall]

I've put osb in places to stop the sides collapsing, braced with a bit of 4x2 etc, is this OK to leave in place and trim down at a later date?

Absolutely. It normally gets trimmed with a sledge hammer on our sites.

 

[^woody^]

We trim ours with a tenon saw

 

[garyo]

I doubt that anyone on here has got away with advising an OP to have a FFL "at the same height as a DPC"?
Sometimes its unavoidable when dealing with existing circumstances but its not advisable to build it in.

May I ask why? I did this a few years ago, because of circumstances as you say: