Good Day my NL followers,

A few days back, one of my active followers here, sent me pictures of his site work which had gotten to filling level, it was obvious (from an experienced view) that his workers/supervisors were doing something wrong, it was obvious the building would collapse if continued - I would be discussing what was done wrong and why the structure eventually gave way - Let's all learn to avoid waste of fund and human life.

1. Foundation: In Pics 1 & 2, it is obvious the foundation was shallow; There are 5 courses of blocks in the foundation, and all 5 are easily seen in both pics, this is a proof that the foundation was shallowly dug - the standard on a good/firm soil is 900mm and where the ground is so firm that you can't get to 900mm (3 feet), then make sure you dig 600mm. This allows some of the block to be rooted in the ground and reduce surface area to be supported by filling.

2. Sub-Structure: If you've been reading my thread on foundation - I've always advised that you have nothing less than 4 courses, so shouldn't 5 courses be an advantage? the answer is NO...... because that would mean having more forces pushing in one direction and no force to counter it on the opposing side ESPECIALLY WHERE THE FOUNDATION IS SHALLOW hence a collapse. Note that, should there be need to go above 4 courses (most times because of sloping land, then short columns or top beam or both should be considered and introduced.

3. Why Did This Foundation Collapse?: Immediately I saw the pictures sent to me, I told him the structure would likely collapse, so I advised him to fill the foundation before doing any other work (as most people because of limited fund, continue building without filling) - The proper construction method is to fill, wet and compact properly, then do your German floor before the Super-Structure.

After filling the foundation, the 1st rain and what I got was picture 3 and 4; so what went wrong?

3a. The foundation was shallow - we have discussed this in 1 above.

3b. The foundation was too high - In my discussion with the client, he noted that the front of the building didn't have 5 courses but only 3. This means the builder was trying to have a level foundation, NOPE - The appropriate thing to do would have been to have stepped down back to 3 courses as he approaches the lower part of the building, this reduces the volume of filling required and also reduces the earth force acting on the walls.

3c. The filling was not done in layers - From the pictures shared (pics 4), you would notice some of the internal walls also collapsed; THIS SHOULD NEVER HAVE HAPPENED EVEN IF THE JOB WAS DONE THE WAY, IT WAS - ONLY THE EXTERNAL WALLS SHOULD HAVE COLLAPSED. So, why did the internal walls collapse? we would deal with this in No 4 below.

4. Filling: Ensure that filling is done in layers, and where two sides of a wall are to be filled, both should be done concurrently, what the supervisor/builder should have done is fill 300mm on one side, then fill 300mm on the other side, then compact. He then returns to fill another 300mm on one side and then 300mm on the opposite side, then compact - what we're doing is making sure that if forces on one side try to push the block to collapse, the force on the other side resist that happening by equally pushing back. If this was done, even thou the construction method in the shared pics was wrong, ONLY THE EXTERNAL WALLS WOULD COLLAPSE, because there is definitely no force to help sustain it.

5. Get the right guy on site: The fact he has been building for 20, 30 years or before we were born isn't a guaranty he would build right, you need a trusted/experienced person making sure (even if it's once every 2 weeks) making sure the right thing is done.


Thanks and remember it might cost you more to get a supervisor, but it would cost the most to rebuild if something goes wrong....

Special Appreciate to the Nairalander for allowing me to use his site as a Case Study. Let's go build this now.


GOODLUCK.

I think the foundation can only be done like this if it is raft foundation. also I only tell people to try do floor slab ( german floor) before continuation of block wall as it helps make the building a unit.

Obviously the foundation wasn't done right. Apart from being too high, the filling wasn't done well. Too much force against the external wall made it to collapse.

You can add a new foundation wall internally around the foundation at th back to give the external some support . Note that this wall will not go above the current 5 courses of blockwall.

A beam has to be done and columns introduced.

Could still be salbavegd.

edimalo:
Obviously the foundation wasn't done right. Apart from being too high, the filling wasn't done well. Too much force against the external wall made it to collapse.

You can add a new foundation wall internally around the foundation at th back to give the external some support . Note that this wall will not go above the current 5 courses of blockwall.

A beam has to be done and columns introduced.

Could still be salbavegd.

Thanks for your submission.. I also think at this stage, the columns and beam is inevitable to help reinforce the weak structure... Unfortunately one man's mistake would mean more being spent..

Thanks

Good narration and suggestions. Builders from hell.
Where are the columns (pillars) for such a high foundation.
What happened to raft... and Yes, shallow holes for first blocks.
Why the foundation no go collapse? God save us o

Hajji M.

Though I am a noob when it comes to construction, it is glaring there are no columns in this build. I couldn't even locate a single one. Who does such. The owner of the building is also blameworthy albeit a little. It is imperative we read to know the basics of home construction and ask questions about our building projects. He who asks is guided aright. We should Learn to be very inquisitive in such matters.

I pray the owner bounces back and gets it right next time. Its better the foundation collapsed now than after completion of the building (if it hasn't yet been completed)

Wagasigiungu:
Though I am a noob when it comes to construction, it is glaring there are no columns in this build. I couldn't even locate a single one. Who does such. The owner of the building is also blameworthy albeit a little. It is imperative we read to know the basics of home construction and ask questions about our building projects. He who asks is guided aright. We should Learn to be very inquisitive in such matters.

I pray the owner bounces back and gets it right next time. Its better the foundation collapsed now than after completion of the building (if it hasn't yet been completed)

Thanks for the prayers and show of concern..... I'm sure he wld bounce back, it hasn't been completed - the owner is also reading.... thanks

Gbese !
Subuhanallah

I took my Free Consultation to a high...

I visited the site discussed in this thread (In Ikorodu).

I have given the Nairaland owner my honest opinion, its really bad of the contractor to work that way....... I would be visiting again to give methodologies for correcting...

Thanks

Part of the modification I suggested is pulling down some of the standing walls; they're showing signs of weakness and / or collapse...

It's a terrible situation.

The owner contacted us some days ago to see how we can reconstruct the foundation with friendly cost.
Thanks God we agreed on a reasonable fee.

Here are some pics I took when I visited the site
I will open a tread for the project

Work stated at site few days ago

rotecch77:
It's a terrible situation.

The owner contacted us some days ago to see how we can reconstruct the foundation with friendly cost.
Thanks God we agreed on a reasonable fee.

Here are some pics I took when I visited the site
I will open a tread for the project

Work stated at site few days ago

great - you can tag me when you start and open the thread........ lets remedy this.... congrats also on the contract...

saydfact:


great - you can tag me when you start and open the thread........ lets remedy this.... congrats also on the contract...

Yea, thanks

This is why I am so scared to buy all these ready built houses. You guys are too economical with cement

4ckTOTO:
This is why I am so scared to buy all these ready built houses. You guys are too economical with cement

Welcome - you can search and read up my post here; thank me later .. lol

saydfact:


great - you can tag me when you start and open the thread........ lets remedy this.... congrats also on the contract...

Here is the link

https://www.nairaland.com/5025706/reconstruction-faulty-foundation-nairalander#75764681

Coooool.. I'm seeing some synergy here by our building gurus collaborating on this defective structure.

I must say well-done and thanks to all the team.

At least let's have the before and after pictures so this can always be a learning point for all.