Monopour foundation

1674 Views 18 Replies 5 Participants Last post by ron45, May 29, 2020

Cambraupod

Discussion Starter · May 18, 2020

I have this sweet form ready to pour with an inner and outer plywood form. It’s going to be a mono pour. The walls are 24 x 12“ and the slab portion is 6 inches. My partner says pack it firm and pull out the inner plywood form and then lay in the rebar. Pour

I’m worried about those nice 90° dirt walls collapsing.

I feel like I’m doing something wrong?

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Nealtw

· #2 · May 18, 2020

You are talking about 2 different systems, is this what you want to do?

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Cambraupod

Discussion Starter · #3 · May 18, 2020

Yes but I placed the Ply inner foundation which is 6” shorter... Should I just leave that 18” tall ply inside the concrete ? Ply B in the illustration?

Nealtw

· #4 · May 18, 2020

Cambraupod said:
Yes but I placed the Ply inner foundation which is 6” shorter... Should I just leave that 18” tall ply inside the concrete ? Ply B in the illustration?

How have you tied inside to outside plywood?

Have you the plumbing done?
Have you compacted the fill?

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Cambraupod

Discussion Starter · #5 · May 18, 2020

Plumbing is in.... Inner and outer have lots of 1x1’s holding the walls apart . Haven’t packed it yet

Nealtw

· #6 · May 18, 2020

Cambraupod said:
Plumbing is in.... Inner and outer have lots of 1x1’s holding the walls apart . Haven’t packed it yet

This is your first foundation?

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Cambraupod

Discussion Starter · #7 · May 18, 2020 (Edited)

Looking at the link above....Ignore the 2X lumber.

The right panel is 24" and the left 18". Everything left of the panel is the slab which finishes out 6" thick. I still need to add some fill.

So to mono pour I am thinking I have to leave that left panel in, under the slab, to avoid caving.

The project is a 20'X12' foundation

Is this method going to give me problems?

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Cambraupod

Discussion Starter · #8 · May 19, 2020

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Msradell

· #9 · May 19, 2020

In answer to your last question, yes it's probably going to give you problems. You need to pull the inner panel out now and sloped the inside portion like Neal posted a diagram of earlier. That's the right way to do it and won't cause any problems. It will take a little more concrete than your method but will be much easier to execute and won't cause any problems.

The other option would be to do 2 pours. That option shouldn't cause any problems either as long as you have rebar extending thru the joint between the 2 of them.

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Cambraupod

Discussion Starter · #10 · May 19, 2020

If I left the inside board there it should be ok wouldn't it? Although I don't know how much I could pack that dirt and keep it in place.

The whole thing is dead on to the `1/16"

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MTN REMODEL LLC

· #11 · May 19, 2020

Cambi....First...You have done a terrific forming job in regard to sort of "technical perfection. "

But, for a mono, unless you have a absurd sloughing ground, that interior is not necessary unless it is somehow integral to supporting your exterior form.

You have not told us where you are and your ground and weather conditions.

But, in general, that interior to your footer can be as wide as you want, and shy of frost issues, more is better.

And in all mono's I know of.... you need rebar between 6the mono footer and slab.

I'd pull it and clean up any sloughing....but if you get the rebar in there, I think you'll be OK.

Good going

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MTN REMODEL LLC

· #12 · May 19, 2020

Cambraupod said:
If I left the inside board there it should be ok wouldn't it? Although I don't know how much I could pack that dirt and keep it in place.

The whole thing is dead on to the `1/16"

I LIKE THAT and it is very commendable... but realistically I think you will find that perfection becomes increasingly important as the job progresses.

Forming...framing...setting windows.... and finish trim/tile etc.

That's not to say do a krap job at forming....but framing is not a dovetail box joint.

I'm betting you end up with a terrific final product...:smile:

Cambraupod

Discussion Starter · #13 · May 19, 2020

Plenty of rebar is on its way...

Nealtw

· #14 · May 19, 2020

Cambraupod said:
View attachment 599351 Looking at the link above....Ignore the 2X lumber.

The right panel is 24" and the left 18". Everything left of the panel is the slab which finishes out 6" thick. I still need to add some fill.

So to mono pour I am thinking I have to leave that left panel in, under the slab, to avoid caving.

The project is a 20'X12' foundation

Is this method going to give me problems?

You are doing something I have never see before but others like what you have, so I will be watching instead of talking.

Cambraupod

Discussion Starter · #15 · May 29, 2020

3

Got it.... done, no issues

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Cambraupod

Discussion Starter · #16 · May 29, 2020

Now cutting out that short wall and it will become one large kitchen/living room..

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ron45

· #17 · May 29, 2020

Where are your J-Bolts.?

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Cambraupod

Discussion Starter · #18 · May 29, 2020

I’ll drill in my anchors when framing ....something wrong with that?

ron45

· #19 · May 29, 2020

Cambraupod said:
I’ll drill in my anchors when framing ....something wrong with that?

In my neck of the woods it is code.

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