help - Can i pour 10" of conc on top of foundations

[gismo]

I recently poured the concrete into my 1m footings for a 2storey extension. i only put in about 500mm as i was limited by my foul drain pipe (cannot be moved unfortunately).

there is a slight fall in the level of the concrete, about 1.5inches over the the 5m length. the correct/high the drain end. i've layed 1 block either side of the drain and have a conc lintel to go over.

my question is, can i now pour 9-10inches of concrete over the rest of the footings (level this time) and begin blocking up from there?

if so do i need to reinforce, or can i simply lay on top of, i worry whether it may crack or something?

any help will be greatly appreciated - stressing out about what to do

 

[Deluks]

If you 12mm drill holes every 600mm and hammer some 12mm rebar into these holes, you are unlikely to have a problem.

 

[themiddleagedun]

There's no need to lay more concrete on top, 1.5'' out of level is no problem.
You'll need a couple of course of brick, under the blockwork, to get it level and away you go...

 

[RedHerring2]

Even one course of 215mm deep trench blocks instead of the 9 - 10" concrete.

http://www.hhcelcon.co.uk/c/document_library/get_file?folderId=54610&name=DLFE-2804.pdf

 

[noseall]

there is a slight fall in the level of the concrete, about 1.5inches over the the 5m length.

Why is there a half course of pig in the concrete levels?

1.5" is not slight, it is awful.

 

[gismo]

thanks for the replies

i already had all the blocks delivered so making up the differnce sounds good, can i cut a few slithers of concrete block to kind of pack out, bout 40mm ish? they're dense blocks, will they take the weight?

 

[Deluks]

As long as there's a mortar bed above and below then cutting bits of block is fine. Could also use paving slabs or roof tiles.

What was the intended depth when you started? Did you pour short or were you just proposing more concrete to level up.

 

[gismo]

i intended for 500mm concrete, block/brick to damp.
i calculated the amount of concreted, added a little extra but it wasn't quite enough which was a pain in the ring, (only bout 2 inches too low)

so we had to spread what concrete i had about, l obviously got it wrong when trying to level it off.

thanks for the help.

p.s Noseall - if you say its awful, yourself being a pro/experienced imagine how stressed i am being as an amateur

 

[Deluks]

imagine how stressed i am being as an amateur

Should've got the pro's in then shouldn't ya

Nah, well done for having a go, hope it goes well, if not you know where to come.

 

[themiddleagedun]

If you want to "level up" using blocks. Probably easier to: find the lowest point of the concrete, lay a full block. At highest end cut enough off a block so when it's laid its level with the original one. (you've got a laser level?) put a line from each one. Cut each block slighly bigger lay 'em to the line. Sorted.

 

[gismo]

[/quote]Should've got the pro's in then shouldn't ya

thats what i thought afterwards - good ol' hindsigh heytlol

Middleagedun -
thats a good idea, i have't got a laser level but do you think i could level up with long piece of wood and spirit level to begin with and then set a line i guess.

thanks guys

 

[RedHerring2]

You might struggle to span 5 metres with one piece of wood but there's nowt wrong with levelling to a midpoint first, then levelling from that.

 

[noseall]

For future reference:

The simplest way of preparing a trench for concrete is to use wooden pegs, every 1.5m or so.

Set the first peg as a datum then, using a straight edge and a 1.2m level, work your way along the trench. If you have more sophisticated tools like a laser then so be it.

But still use pegs as these are a physical indicator of where you want the poured concrete to finish.

For the sake of a couple of hours work, pegs can save a lot of pain and misery. Concreting is heavy and laborious work at the best of times so get it right first time.

 

[gismo]

i should have used that method to begin with, i have got plan permission to extend my garage too so i'll make sure i use your method then thanks noseall,

i'm really greatful for the advice you all gave, thanks