Foundation Depth - How DEEP is deep enough?

I always wonder "What does a client need to know about foundations?" I think it is a subject that should be left for the structural engineers alone. But should we really do that? No, we need to understand the basics.

Foundation Design/Engineering is the most boring subject I've ever heard from engineers. It defies logic. I used to assume that the higher the structure, the deeper the foundation.

However, I've found out that foundation depth does not depend upon height. More height means more loads coming on the soil which means greater strength required at the width of the base rather than depth

Foundation depth depends upon various factors like:

1. Bearing capacity of the soil, which explains the reason why pile foundation is recommended in areas with insufficient bearing soil.
2. Function of the building (public carparks, auditorium, private residence, MTUs etc)
3. Wind loads
4. Depth of water table.

Pro: I totally disagree with you, the higher a building goes, the deeper the foundation should go. You rightly stated Wind load as a factor to be considered. Wind loads and building heights have a direct proportionality (i.e the higher a building goes, the higher the Wind load). Pressure increases with depth, therefore the active earth pressure coupled with other factors such as Column strength, shear walls and bracing (if provided) needed to sufficiently resist such horizontal loads as wind load can only be achieved with an increase in depth. That's the width strength you were referring to.

The Burj Dubai Tower (at 818m or 2,684-ft height or almost exactly 1/2 a mile) has a 3.7m thick raft foundation sitting on 50m deep bored piles. I would expect the founding depth of such structure to be more deep

EgunMogaji:


And this is why I brought the subject here specifically to hear from you Pros in the house. There are other threads on here but this is the critical one because of that vey fact. We haven't hear from the Chairman himself, the Alarararuru or Arururara 1 Spyder880, I think he put up a 5 or maybe 4 story flat at least once before.

But as it is in real life you'll have rabid Dogs barking here and there, whatyougonnado

Following the discussion with rapt attention, the bold got me laughing

abdulwastecx:


An experienced architect should not do all the drawings ( structural drawings) should be left to people who understand it, people who has been certify to carried them out.
Electrical design for bigger building should be done by an electrical engineer.

Structural failure is a combination of so many factors that people who are not conversant with soil behavior and structural behavior may not understand.
Stability of structures depend on sound knowledge of soil engineering properties which can only be gotten through extensive and detail soil text. It also depends on good structural design done according to codes.

EgunMogaji:

Au Con·traire por favor El Maestro
What if the Architect is also a Structural Engineer or part of a cooperative of professionals.

skimanski:
Oga Brabus I can see you know a lot about Structural Calcs. Your professionalism na top. but lets come down to the level of laymen like us. forget those story of Following Structural Calculation to confirm the Live/Dead Load Analysis, Steel Analysis, Shear Force and Movement Information. Thats not what I feel is the problem, those na many grammar.

This is a Clear case of Lekki Garden Bring Small Money put am for contractor hand, and expect contractor to make the figure work no matter what, and Contractor collects what he feels is his gain inside and use the remainder to work, before you know the money becomes too micro for the project. The major blame should go to the buyers who like Cheap things, you want to buy a house with money you know wont build you Carcass. didnt you think of how is it possible for the Sellers to make gain like. Oh! the sellers are not there to make gain right? only you the buyer is expected to gain from the process right? Thats a case of when people deceive their selves. you want to buy things with money you know isn't realistic and expect to get what you want. O.Y.O is their case anyway. Lekki Gardens Build Cheap Houses because they know people like their Buyers are everywhere. They want to eat their cakes and still have it.

skimanski:

This is a Clear case of Lekki Garden Bring Small Money put am for contractor hand, and expect contractor to make the figure work no matter what, and Contractor collects what he feels is his gain inside and use the remainder to work, before you know the money becomes too micro for the project.

skimanski:


This is a Clear case of Lekki Garden Bring Small Money put am for contractor hand, and expect contractor to make the figure work no matter what, and Contractor collects what he feels is his gain inside and use the remainder to work, before you know the money becomes too micro for the project. The major blame should go to the buyers who like Cheap things, you want to buy a house with money you know wont build you Carcass. didnt you think of how is it possible for the Sellers to make gain like. Oh! the sellers are not there to make gain right? only you the buyer is expected to gain from the process right? Thats a case of when people deceive their selves. you want to buy things with money you know isn't realistic and expect to get what you want. O.Y.O is their case anyway. Lekki Gardens Build Cheap Houses because they know people like their Buyers are everywhere. They want to eat their cakes and still have it.

texazzpete:

Sure, lekki gardens houses are relatively cheaper than most other developers, but they aren't really CHEAP. You'd be paying N25+ million for a carcass terrace duplex...and that's not dirt cheap. Even taking out costs for the land itself (which is drastically reduced due to the density of LG buildings + terrace/apartment development), there are many here that build their houses with money in the same ballpark.

Tvegas:


Anyhow we wanna cut this ,buyers are also partly responsible. Some buyers never visit the site before paying. A brief visit to some of those sites will reveal poor constructions going on.

brabus:


And I never looked at it from your perspective to blame it on the client.

texazzpete:


That's because you're a smart fellow and inherently you know it's ridiculous to blame the client for this mishap

texazzpete:


I see this extremely stupid point of view, and it baffles me all the time.

Sure, lekki gardens houses are relatively cheaper than most other developers, but they aren't really CHEAP. You'd be paying N25+ million for a carcass terrace duplex...and that's not dirt cheap. Even taking out costs for the land itself (which is drastically reduced due to the density of LG buildings + terrace/apartment development), there are many here that build their houses with money in the same ballpark.

Also, LG makes extra money from the service charges and running fees from homeowners.

Some of you talk like the houses cost N5million each, That's far from the truth.

the prices for these buildings were set by Lekki Gardens. Customers just pay. To try to shuffle the blame for poor construction standards and rampant disregard for building rules on the customer is just plain daft.

Uberness:




True My Prof. @ Abdulwastecx, The Structural drawing was of course produced by the Structural Engr. in question and all other protocols were equally duelly observed.
You can trust me on this.

@ Oga EgunMogaji you hit it on the sweet spot.
Merci.

skimanski:




Ahhh!!!! comeon you dont insult people nah! is that how you talk? If you like Cheap things, you buy nah. If you disagree with my comments,you just disagree and dont Insult.

China makes Phones that do not last the 5th Charging Circle, or that might burn your other appliances, so are you telling me the biggest problem to that is the Government control or the Subcribers? You buy a house for 25m. Thats not even up to the price of land in that area. but you want to use that money to own a complete house, whose Daft now? You can see the Writing on the wall yet you still push the botton and open the door. So whose Daft?

Please Carefully comment next time and dont insult people. I beg you. Lets be matured.

skimanski:

Ahhh!!!! comeon you dont insult people nah! is that how you talk? If you like Cheap things, you buy nah. If you disagree with my comments,you just disagree and dont Insult.

skimanski:

China makes Phones that do not last the 5th Charging Circle, or that might burn your other appliances, so are you telling me the biggest problem to that is the Government control or the Subcribers? You buy a house for 25m. Thats not even up to the price of land in that area. but you want to use that money to own a complete house, whose Daft now? You can see the Writing on the wall yet you still push the botton and open the door. So whose Daft?

twinskenny:
they are claiming that the workers suppose not to be sleeping on site... so they want to tell us that they are not aware of that from the beginning>?

it is well... i know the contractor is in deep trouble

texazzpete:


I didn't 'insult' you. It was a silly comment you made, and i stated that accordingly.



Nobody is buying a standalone house for N25m. Did the part i mentioned about 'land density' fly out through your ear? The land for these type of estates are acquired as a bulk purchase, and because of the terrace or apartment design, several housing units are fitted on one plot of land, drastically driving down the unit cost of land per house. When the economics are run, there's perfectly enough cash to build a safe, secure house. It all depends on the business model. If the developer's plan is to minimize profit on the house to maximize returns from estate management, service charge fees etc, where's your analysis to say this is not a viable business model?

Your problem is that you speak out of ignorance. There are MANY business areas where these models are used, and they work pretty well. Sony sells the Playstation 4 at cost (or even a small loss) at $299, but they make billions in profit from sales of games, licencing fees and yearly subscription for online play.

Using your 'China' example, take a look at Xiaomi. They sell a phone with pretty much the exact same specs as the $700 Galaxy S7 for $400. While Samsung makes profit from the hardware sales, Xiaomi's business model is to sell their phones at razor thin margins yet make hundreds of millions in profits from sales in the preloaded Xiaomi appstore. This has paid off since they are now one of the top 7 phone manufacturers in the world.

Your darling estate developers that sell houses at a premium are using the 'Samsung' approach. They sell FEWER units with a higher per unit profit. Lekki Gardens should nominally be on the 'Xiaomi' approach. Selling a crazy boatload of houses at small profit margins, but much higher returns from service charges.

Then you - with your limited understanding - pop up to claim that the MAJOR culprits in an apartment block collapse that killed 25 people are the folks who paid money for these flats. And you consider it an insult when you're rightfully challenged over the inanity of this claim.


And to clarify, the N25m for a terrace duplex is only in places like Ajah where land prices are MUCH cheaper than in the area where the building collapsed.

"If you buy land for 25m, you're not expected to build with nothing less than 50m even if it's a glorified block of flat like The Horizon" - author unknown

abdulwastecx:


That is a very important question sir. Heavy structural work should always a registered structural engineer (civil engineer) coming to site from milestone to milestone to check progress of work and making sure what was designed is followed properly.

texazzpete:


I didn't 'insult' you. It was a silly comment you made, and i stated that accordingly.



Nobody is buying a standalone house for N25m. Did the part i mentioned about 'land density' fly out through your ear? The land for these type of estates are acquired as a bulk purchase, and because of the terrace or apartment design, several housing units are fitted on one plot of land, drastically driving down the unit cost of land per house. When the economics are run, there's perfectly enough cash to build a safe, secure house. It all depends on the business model. If the developer's plan is to minimize profit on the house to maximize returns from estate management, service charge fees etc, where's your analysis to say this is not a viable business model?

Your problem is that you speak out of ignorance. There are MANY business areas where these models are used, and they work pretty well. Sony sells the Playstation 4 at cost (or even a small loss) at $299, but they make billions in profit from sales of games, licencing fees and yearly subscription for online play.

Using your 'China' example, take a look at Xiaomi. They sell a phone with pretty much the exact same specs as the $700 Galaxy S7 for $400. While Samsung makes profit from the hardware sales, Xiaomi's business model is to sell their phones at razor thin margins yet make hundreds of millions in profits from sales in the preloaded Xiaomi appstore. This has paid off since they are now one of the top 7 phone manufacturers in the world.

Your darling estate developers that sell houses at a premium are using the 'Samsung' approach. They sell FEWER units with a higher per unit profit. Lekki Gardens should nominally be on the 'Xiaomi' approach. Selling a crazy boatload of houses at small profit margins, but much higher returns from service charges.

Then you - with your limited understanding - pop up to claim that the MAJOR culprits in an apartment block collapse that killed 25 people are the folks who paid money for these flats. And you consider it an insult when you're rightfully challenged over the inanity of this claim.


And to clarify, the N25m for a terrace duplex is only in places like Ajah where land prices are MUCH cheaper than in the area where the building collapsed.

skimanski:

Anyhow incase you missed it, I said the major blame goes to the buyers. Never said Lekki gardens nor government were not to blame. So go next time read through things before your look for opportunity to insult people. But if you feel u can't comment without insulting me, then don't bother commenting, I will understand it's the way you are and can't change. But if you comment and do not insult me, then kudos, it means you've grown and I've improved impacted on your life today. However if you feel you want to comment and continue insulting then my brother Na God go hand that one dey ooo.

skimanski:

Anyway my understanding of this what you are saying is that, If Hyundai tells you they can make Gwagon for Hyundai price and with Hyundai parts you will believe ? Who does that?

skimanski:

If you tell me it's right to go with Lekki gardens despite all the poor ratings, then you are entitled to your own opinion.

texazzpete:


I didn't 'insult' you. It was a silly comment you made, and i stated that accordingly.



Nobody is buying a standalone house for N25m. Did the part i mentioned about 'land density' fly out through your ear? The land for these type of estates are acquired as a bulk purchase, and because of the terrace or apartment design, several housing units are fitted on one plot of land, drastically driving down the unit cost of land per house. When the economics are run, there's perfectly enough cash to build a safe, secure house. It all depends on the business model. If the developer's plan is to minimize profit on the house to maximize returns from estate management, service charge fees etc, where's your analysis to say this is not a viable business model?

Your problem is that you speak out of ignorance. There are MANY business areas where these models are used, and they work pretty well. Sony sells the Playstation 4 at cost (or even a small loss) at $299, but they make billions in profit from sales of games, licencing fees and yearly subscription for online play.

Using your 'China' example, take a look at Xiaomi. They sell a phone with pretty much the exact same specs as the $700 Galaxy S7 for $400. While Samsung makes profit from the hardware sales, Xiaomi's business model is to sell their phones at razor thin margins yet make hundreds of millions in profits from sales in the preloaded Xiaomi appstore. This has paid off since they are now one of the top 7 phone manufacturers in the world.

Your darling estate developers that sell houses at a premium are using the 'Samsung' approach. They sell FEWER units with a higher per unit profit. Lekki Gardens should nominally be on the 'Xiaomi' approach. Selling a crazy boatload of houses at small profit margins, but much higher returns from service charges.

Then you - with your limited understanding - pop up to claim that the MAJOR culprits in an apartment block collapse that killed 25 people are the folks who paid money for these flats. And you consider it an insult when you're rightfully challenged over the inanity of this claim.


And to clarify, the N25m for a terrace duplex is only in places like Ajah where land prices are MUCH cheaper than in the area where the building collapsed.

EgunMogaji:


And this is why I brought the subject here specifically to hear from you Pros in the house. There are other threads on here but this is the critical one because of that vey fact. We haven't hear from the Chairman himself, the Alarararuru or Arururara 1 Spyder880, I think he put up a 5 or maybe 4 story flat at least once before.

But as it is in real life you'll have rabid Dogs barking here and there, whatyougonnado

Rescue work ends at collapsed Lekki house

The final death toll at the collapsed Lekki five storey-building was 34, with another 13 people rescued.

Rescue operators have now called off the operation having reached ground zero.

Ibrahim Farinloye, PRO of the National Emergency Management Agency (NEMA) said in a statement today and that the attention of the various federal and state agencies has turned into investigating the cause of the building collapse.

The five storey building which was under construction, located at Chisco Bus Stop near Oando Filling Station, Lekki collapsed early in the morning on March 8.

“The operation to rescue those trapped in the collapsed structure, belonging to Lekki Gardens started at about 4 a.m. on March 8 and ended by 7.20 p. m. on March 9.

“Those rescued alive are receiving treatment in various hospitals in Lagos metropolis,’’ Farinloye said.

brabus:



Patiently awaiting the reports and recommendations of each agencies. That's what matters now.

I can only hope they'll also call the subscribers to come and take their fair share of the blame. Though they are not on my own menu.

But it seems someone in govt is reading up what we've been discussing here on nairaland. First, they didn't want to mention the name of the developer (a certain building in Ikate...) until we voiced it out. Second, they didn't want to issue a press release until we took to the street chanting "we no go gree." Thirdly, NIOB is condemning the brazen act of the developer after we call them out (This is like first time, i'll hear them talk on issue like this). Now, all relevant agencies (federal and states) have been called out just as we recommended 2 days ago. Don't be surprised this case will be the beginning of the change we've all been waiting for. Mark my (packaged) words.

Because we will school them on how it ought to be. Lets forget, how it has been.

Change is possible if rightly administered.

abdulwastecx:


Wholesome analysis sir. It is clear that the customer ( home owner) have zero blame, since they pay for a service that was rendered by a supposed competent film. The blame should be on the developer.

It make business sense as clearly illustrated by you, and to think of it this way, less than 10 % of Nigeria population can even come up with a 25% for a dwelling accommodation.

It is sad that people who invest their hard earned money lost their investment to a dubious organization

oyb:


everybody is liable

lasbca - who are meant to monitor building construction, but are only concerned with shutting down sites so they can collect settlement, after which work continues.

Lekki gardens who clearly do not have any quality control/quality assurance in their processes. it would seem their building plan is execute by cheapest vendor possible. they may also have deviated on the original approved design

the contractor[s] - who executed poor site safety management, and who have cut corners [possibly due to very low margins of greed, or plain incompetence].

the supervising consultants - who did not raise any alarm when QA was circumvented.

it will be interesting to see how much of the standard process was followed - this will be a guide to liability.

alot of people have entered one chance with this.

this is not TB joshua who can bamboozle people with touch not my anointed BS. people are going down.

brabus:



Patiently awaiting the reports and recommendations of each agencies. That's what matters now.

I can only hope they'll also call the subscribers to come and take their fair share of the blame. Though they are not on my own menu. But I definitely have something for them. They should kindly submit their Testimonies (in 2 paragraphs) to their Pastors and Alfas for saving them from untimely death.

However, it seems someone in govt is reading up what we've been discussing here on nairaland. First, they didn't want to mention the name of the developer (a certain building in Ikate...) until we voiced it out. Second, they didn't want to issue a press release until we took to the street chanting "we no go gree." Thirdly, NIOB is condemning the brazen act of the developer after we call them out (This is like first time, i'll hear them talk on issue like this). Now, all relevant agencies (federal and states) have been called out just as we recommended 2 days ago. Don't be surprised this case will be the beginning of the change we've all been waiting for. Mark my (packaged) words.

Because we will school them on how it ought to be. Lets forget, how it has been.

Change is possible if rightly administered.

texazzpete:


Well said.

To think they tried to hide the involvement of Lekki Gardens at first.

35 dead...such a tragic loss. This is probably top 5 in the deadliest building collapse incidents in Nigeria.

Ambode seems ready to crack down on LG, especially since it is a dragon that can be tamed easily, unlike TB Joshua