Can the foundation be poured as 3 separate pieces?

[Tommy2000GT]

I need to replace the crumbling foundation for my detached garage.

The contractor wants to replace the foundation by doing one side at a time. So essentially the foundation will be 3 separate pieces because there are 3 sides. He wants to do one side at a time so he can support 1 wall at a time.

Aren't foundations usually poured was one single continuous piece at the same time? I'm concerned that 3 separate pieces will not be as strong.

 

[Humpy]

Yes, it can be 3 separate pieces. Think of bridge foundations that are separated by hundreds of feet. Yours can/will still be tied together very well with rebar.

The alternative is for you to pay to support the entire structure off the ground at once to pour one continuous footing. It's unnecessary.

They are usually poured in one continuous pour because it's quicker/easier. What's important is that the ground underneath is undisturbed or properly compacted so there won't be any settling.

 

[Red Squirrel]

I would make sure that the end has rebar sticking out so that the next piece can then have that rebar as part of it. Use various angles too. Use cement adhesive as well on the edge of the old pour. (it usually comes in a jug and it's white like milk)

 

[lxskllr]

Yes, it can be 3 separate pieces. Think of bridge foundations that are separated by hundreds of feet. Yours can/will still be tied together very well with rebar.

The alternative is for you to pay to support the entire structure off the ground at once to pour one continuous footing. It's unnecessary.

They are usually poured in one continuous pour because it's quicker/easier. What's important is that the ground underneath is undisturbed or properly compacted so there won't be any settling.

Further more, bridge abutments are usually poured in stages when traffic has to be maintained. There's zero issue with doing concrete in phases.

 

[Red Squirrel]

For bridges typically sections are all a single pour though, each section is independently supported by various beams, supports etc. You would not pour half then rely on the concrete or rebar for the other half. There would be a support at the point where the pour ended. Typically they are actually kept separate to allow for some movement. Sometimes they're even precast. A house foundation is a bit different though as while it is supporting the house, it's not really supporting itself so it's mostly the compression strength that matters more than anything. You could technically build a house on blocks that arn't cemented in and it would hold it fine. But it would move over time from frost heave, so you would not want to do that.

 

[Humpy]

For bridges typically sections are all a single pour though, each section is independently supported by various beams, supports etc. You would not pour half then rely on the concrete or rebar for the other half. There would be a support at the point where the pour ended. Typically they are actually kept separate to allow for some movement. Sometimes they're even precast. A house foundation is a bit different though as while it is supporting the house, it's not really supporting itself so it's mostly the compression strength that matters more than anything. You could technically build a house on blocks that arn't cemented in and it would hold it fine. But it would move over time from frost heave, so you would not want to do that.

It depends on the design, and concrete has a huge variation in design potential. The Hoover Dam bypass was mostly cast in place in hundreds of pours using rebar, post tensioning, cantilevers, arches, etc. There are precast beams that can be bolted together mid-span, or post tensioned. Concrete is really only good in compression, there are any number of ways to provide the tension to hold a structure together.

Also, you Canadians may not believe it, haha, but there are places on Earth that do not ever freeze. Warm places with birds chirping and fruit hanging from trees where you can plop a building down on the ground and it will sit there just fine for centuries.

 

[lxskllr]

For bridges typically sections are all a single pour though, each section is independently supported by various beams, supports etc. You would not pour half then rely on the concrete or rebar for the other half. There would be a support at the point where the pour ended. Typically they are actually kept separate to allow for some movement. Sometimes they're even precast. A house foundation is a bit different though as while it is supporting the house, it's not really supporting itself so it's mostly the compression strength that matters more than anything. You could technically build a house on blocks that arn't cemented in and it would hold it fine. But it would move over time from frost heave, so you would not want to do that.

90% of the bridges I've done have been poured in phases. Pretty much the only time it isn't is on brand new roads or major realignments where traffic doesn't have to be maintained. Additionally, they can be built up(vertically) in phases, especially on tall piers. Typically, the columns are poured first, then the cap is poured on top.

 

[Humpy]

90% of the bridges I've done have been poured in phases. Pretty much the only time it isn't is on brand new roads or major realignments where traffic doesn't have to be maintained. Additionally, they can be built up(vertically) in phases, especially on tall piers. Typically, the columns are poured first, then the cap is poured on top.

What was your role in bridge construction?

I always wished that, before I bailed completely from everything construction related, that I could be involved in a big bridge or infrastructure project. I'd been involved with $50 million light commercial projects, but missed out on the $100 million or $1 billion heavy stuff.

 

[lxskllr]

What was your role in bridge construction?

Surveyor. It is kind of fun. I particularly like bridges, but roads can be tedious. It's still work. If I won a million dollars, I'd quit and never look back, but there's worse ways of making money.

 

[Tommy2000GT]

Ok the foundation has been done, poured in 3 separate pieces. The old foundation was a mess. Whoever poured the foundation before did not use any rebar. The soil around the garage is sloped so the left side of the top of the old foundation and the wood framing was 3 inches below the soil and the wood framing was rotted away. The new concrete foundation is 6 inches above the soil and 18 inches below the soil.

But I have a few concerns but the contractor assured me these things will not be an issue.

1) Instead of using ready-mix concrete, they used Quikrete #1101 high strength 80lb bags and mixed themselves using a portable mixer. Would it have been better to use ready-mix from a concrete truck? The contractor said he can't ask the concrete truck to come 3 times because there is a minimum load.

2) The foundation and footers were poured as one single piece. Any concerns here?

3) No vapor barrier was used. I found out today researching online there should be a vapor barrier between the soil and foundation. Should I be concerned here?

4) They stripped the forms and did framing the next day after the concrete was poured. The sill plates were tightened down to the foundation tie downs also. Isn't this too early?

It seems like they are rushing to finish the job quickly. They used a lot of tie downs (1/2" diameter tie downs every 24" apart) and Simpson HDU5 holdowns at each corner. I hope this enough to keep it all together.

 

[Humpy]

Ok the foundation has been done, poured in 3 separate pieces. The old foundation was a mess. Whoever poured the foundation before did not use any rebar. The soil around the garage is sloped so the left side of the top of the old foundation and the wood framing was 3 inches below the soil and the wood framing was rotted away. The new concrete foundation is 6 inches above the soil and 18 inches below the soil.

But I have a few concerns but the contractor assured me these things will not be an issue.

1) Instead of using ready-mix concrete, they used Quikrete #1101 high strength 80lb bags and mixed themselves using a portable mixer. Would it have been better to use ready-mix from a concrete truck? The contractor said he can't ask the concrete truck to come 3 times because there is a minimum load.

2) The foundation and footers were poured as one single piece. Any concerns here?

3) No vapor barrier was used. I found out today researching online there should be a vapor barrier between the soil and foundation. Should I be concerned here?

4) They stripped the forms and did framing the next day after the concrete was poured. The sill plates were tightened down to the foundation tie downs also. Isn't this too early?

It seems like they are rushing to finish the job quickly. They used a lot of tie downs (1/2" diameter tie downs every 24" apart) and Simpson HDU5 holdowns at each corner. I hope this enough to keep it all together.

1. In general there is no difference between bagged concrete and concrete delivered by truck. Both have to be mixed with the correct amount of water to reach full strength, etc.

2. No concerns here as long as there form work, rebar, and placement of concrete was done competently.

3. In general this is not an issue. Concrete itself does not have to be protected from water vapor. Was a slab poured at the same time? Plastic under the slab is useful for a variety of reasons. Mainly because it helps the concrete cure. It also can help prevent ground water entering the building but that is much more important for a finished space.

4. These small jobs have to be done quickly and efficiently or the contractor does not make a living. There are dangers with working over uncured concrete but they aren't insurmountable. For example, they shouldn't have torqued down the anchor bolts more than finger tight plus a quarter turn or so. You check them at the end of the job.

Nothing here raises any red flags for me.

 

[Tommy2000GT]

Thanks. The new foundation seems very robust. I just hope they got the correct of water/concrete mix. It doesn't seem like they were really measuring how much water. They were just spraying water into the mixer until they felt the consistency was right.

 

[Greenman]

You can actually tell when the mix is right by the sound it makes as it rolls off the top of the mixer. Obviously that's not as good as actually measuring the water content, but it's surprisingly close.