Engr. Osaz' Enobakhare (Lagos, Nigeria)

As construction cost rises due to attendant rise in prices of building materials, the trend of building houses directly on sand has been observed to be on the increase especially by unscrupulous developers and contractors. Having carried out an independent monitoring of construction activities in some areas in the Ajah axis of Lagos lately, it became obvious that in order to save cost people have resorted to constructing buildings directly on sand.

The awkward idea been adopted in most of the cases under study is to sand-fill the land, level and compact it with the use of machines and the construct a reinforced concrete strip foundation directly over it without recourse to minimum construction/engineering standards. They do so very quickly so that before any of the regulatory bodies saddled with the responsibility of building control gets wind of their ill act, they are already on super-structure level at which point it is burdensome to ascertain how the foundation was actually built.

On a particular site, using this vague method the entire foundation including the ground floor slab was put up in one week and by the next week, they were already building up the walls and frame. Dishonest developers thrive in such indecent acts and sell or lease these buildings to unsuspecting prospective buyers who in-turn occupy them or cause others to do so by way of lease/rent too. There is no consideration for lives and properties put at risk of an imminent collapse even as some of the buildings observed are already exhibiting symptoms of instability and sick building syndrome pre-occupancy.

Five years post-occupancy, the building over-settles (or sink) and then tilt in a particular direction. When asked, some of these developers claim that before there will be any major issue with the building they would have recouped the returns on their investment and its left to the new owner to do a repair by way of underpinning as the need arises. To know that some greedy professionals have joined the bandwagon of quacks in delivering such poor structures is condemnable. This act should not be encouraged in any form.

Here are some structural considerations; normally after leveling and compacting operation has been carried out on a sand-filled land it still remains a made-up ground. Although the land becomes stiff at sub-surface levels, this doesn’t in anyway erase the fact that the underlying bad soil (or peat) remains intact and retains its poor attributes. Peats are highly compressible soils and will naturally compress upon the impact of load. As this happen, the building will settle indifferentially, especially during seasonal changes and mass movement of the earth; which occurs at various times of the year. Such structural anomaly often leads to poor stability of the building and eventually a collapse if unable to bear the load, especially for single or multi-storied structures.

Rising cost of building materials should not be a yardstick to adopt poor construction methods in the construction of buildings and estate infrastructure anywhere. The authorities should not turn a blind eye to such activities that jeopardizes or threatens the lives of people as well as the overall health of the built environment. Project owners and developers should not connive with contractors or builders to manipulate well established engineering prinicples. It is important to select a good contractor for your projects. Yes, there is room for adopting cost-saving methodologies like the use of dry construction methods, cold brick construction, etc but bad construction methods is never the way to go.


Source: http://engineerosaz..com/2017/03/why-it-is-structurally-wrong-to-build.html

Good information.

Sure

.

No wonder there's a huge surge of building collapse these days unlike previous years

It's really people that are killing themselves or others these days and not some accused village witches and what nots

Those involved should please desist

This is also a lesson to all of us that we should try starting things from the foundational level.. If the foundation of a thing is not solid the sophisticated structure will lead to a sophisticated collapse

Start building your dreams from the foundation and do everything you need to do from the foundation because cutting corners most times lead to cutting short that sophisticated life you planned on living

Long live Nigeria
Long live Nigerians
Long live Nairalanders

Good morning

It's even biblically wrong and unacceptable.

Oga try biuld on sand and see .

ok

Although I haven't seen such before but aside the fact that the idea is technically wrong, from the attached picture , you mean the foundation will be sitting on just sand ?? That's kind of funny though. Most definitely the floor level will be extremely high..


People really needs to stop cutting corners unnecessarily

Ok

Even the parable of wise and foolish builders as reflected in the Gospel of Mathew captures the consequences...."Everyone who hears these words of mine, and doesn't do them will be like a foolish man, who built his house on the sand. The rain came down, the floods came, and the winds blew, and beat on that house; and it fell—and great was its fall".

Well it depends on type of foundation you are using
If u are doing a raft foundation ,u don't need to dig down ,just make ur form work, reinforced it ,you are good to go, since d surrounding Is still going to be fill with sharp sand.

But in situations of hollow block.. ..dont try it

Rampant

Barselonia:
Well it depends on type of foundation you are using
If u are doing a raft foundation ,u don't need to dig down ,just make ur form work, reinforced it ,you are good to go, since d surrounding Is still going to be fill with sharp sand.

But in situations of hollow block.. ..dont try it

Sir, even when you're doing raft you still have to dig to depth that would contain it before any construction.

so we should build on water

Nice one.

---

Wonde....
House on the Rock abi.

Tekecoms1:
It's even biblically wrong and unacceptable.

jeftalene:
Engr. Osaz' Enobakhare (Lagos, Nigeria)

As construction cost rises due to attendant rise in prices of building materials, the trend of building houses directly on sand has been observed to be on the increase especially by unscrupulous developers and contractors. Having carried out an independent monitoring of construction activities in some areas in the Ajah axis of Lagos lately, it became obvious that in order to save cost people have resorted to constructing buildings directly on sand.

The awkward idea been adopted in most of the cases under study is to sand-fill the land, level and compact it with the use of machines and the construct a reinforced concrete strip foundation directly over it without recourse to minimum construction/engineering standards. They do so very quickly so that before any of the regulatory bodies saddled with the responsibility of building control gets wind of their ill act, they are already on super-structure level at which point it is burdensome to ascertain how the foundation was actually built.

On a particular site, using this vague method the entire foundation including the ground floor slab was put up in one week and by the next week, they were already building up the walls and frame. Dishonest developers thrive in such indecent acts and sell or lease these buildings to unsuspecting prospective buyers who in-turn occupy them or cause others to do so by way of lease/rent too. There is no consideration for lives and properties put at risk of an imminent collapse even as some of the buildings observed are already exhibiting symptoms of instability and sick building syndrome pre-occupancy.

Five years post-occupancy, the building over-settles (or sink) and then tilt in a particular direction. When asked, some of these developers claim that before there will be any major issue with the building they would have recouped the returns on their investment and its left to the new owner to do a repair by way of underpinning as the need arises. To know that some greedy professionals have joined the bandwagon of quacks in delivering such poor structures is condemnable. This act should not be encouraged in any form.

Here are some structural considerations; normally after leveling and compacting operation has been carried out on a sand-filled land it still remains a made-up ground. Although the land becomes stiff at sub-surface levels, this doesn’t in anyway erase the fact that the underlying bad soil (or peat) remains intact and retains its poor attributes. Peats are highly compressible soils and will naturally compress upon the impact of load. As this happen, the building will settle indifferentially, especially during seasonal changes and mass movement of the earth; which occurs at various times of the year. Such structural anomaly often leads to poor stability of the building and eventually a collapse if unable to bear the load, especially for single or multi-storied structures.

Rising cost of building materials should not be a yardstick to adopt poor construction methods in the construction of buildings and estate infrastructure anywhere. The authorities should not turn a blind eye to such activities that jeopardizes or threatens the lives of people as well as the overall health of the built environment. Project owners and developers should not connive with contractors or builders to manipulate well established engineering prinicples. It is important to select a good contractor for your projects. Yes, there is room for adopting cost-saving methodologies like the use of dry construction methods, cold brick construction, etc but bad construction methods is never the way to go.


Source: http://engineerosaz..com/2017/03/why-it-is-structurally-wrong-to-build.html

I enjoyed reading your post. CFA piling is a potential solution to overcoming a weak soil with poor subgrade reaction and bearing pressure. The problem with construction in Nigeria is there are no strong Building Controls,Health and Safety Executive and Construction regulations that punishes poor construction. People are more concerned with getting the building up irrespective of the ground conditions and the construction methodology adopted.

Barselonia:
Well it depends on type of foundation you are using
If u are doing a raft foundation ,u don't need to dig down ,just make ur form work, reinforced it ,you are good to go, since d surrounding Is still going to be fill with sharp sand.

But in situations of hollow block.. ..dont try it

The main purpose of adopting a raft foundation is to prevent differential settlement.

Even if you are adopting a raft foundation, the technicality and logics shouldn't be compromised. You still need to carry out soil test/investigation to ascertain the suitability. Otherwise piling will be best here.

COOLDK:


The main purpose of adopting a raft foundation is to prevent differential settlement.

Even if you are adopting a raft foundation, the technicality and logics shouldn't be compromised. You still need to carry out soil test/investigation to ascertain the suitability. Otherwise piling will be best here.

If the weak soil is excavated to quite stronger soil at about -1.5m with better bearing pressure and then a reinforced raft can be adopted.But in very loose sand with high water table, piling might be the only option.

Very informative and well written...thanks for sharing

If from your soil investigation, raft foundation is recommended for your building (mostly when it's not more than a storey building) and if the soil type is a sandy soil like that of Lekki axis, you can go ahead to construct your foundation beams after proper remover of vegetative cover, sand filling with sharp sandand proper compaction.

But in a situation where we have loamy or clayey soil, it is recommended to dig to a point where the soil is compact enough as required by the structural engineer before the foundation work, either raft or strip foundation.

What I know quite well is that settlement is very minimal in a well compacted sandy soil especially when raft foundation is adopted.

Oga abdulwastecx and
Aventures can shed more light on this

kingphilip:
No wonder there's a huge surge of building collapse these days unlike previous years

It's really people that are killing themselves or others these days and not some accused village witches and what nots

Those involved should please desist

This is also a lesson to all of us that we should try starting things from the foundational level.. If the foundation of a thing is not solid the sophisticated structure will lead to a sophisticated collapse

Start building your dreams from the foundation and do everything you need to do from the foundation because cutting corners most times lead to cutting short that sophisticated life you planned on living

Long live Nigeria
Long live Nigerians
Long live Nairalanders

Good morning

Soil investigation is the primary solution to this building collapsing

lol Engr. indeed the land is filled and is almost like digging down.. this buildings are structurally fit. the funny thing with Nigerians is anything other than the norm is bad... with out proper research u conclude.. this houses are not built with stripped concrete it continuous beams foundation but are most times chained with rafts for even settlements and this buildings are not high rises with much dead load but just duplexes.. so as an engr op, u should do d maths well and know if it is possible not saying because of what u believe dat is wrong some Nigerian structural engineer have analyzed this and deemed it fit and economically suitable.. its usually used in water logged areas like lekki ajah phases.. please don't spread wrong messages that breed fear

swazpedro:
lol Engr. indeed the land is filled and is almost like digging down.. this buildings are structurally fit. the funny thing with Nigerians is anything other than the norm is bad... with out proper research u conclude.. this houses are not built with stripped concrete it continuous beams foundation but are most times chained with rafts for even settlements and this buildings are not high rises with much dead load but just duplexes.. so as an engr op, u should do d maths well and know if it is possible not saying because of what u believe dat is wrong some Nigerian structural engineer have analyzed this and deemed it fit and economically suitable.. its usually used in water logged areas like lekki ajah phases.. please don't spread wrong messages that breed fear

I really don't understand your epistle.

To start with, how many of clients carry out comprehensive soil tests?

What is the average soil bearing capacity for areas like Lekki n Ajah?

What is the preferred foundation type for such areas?

What we have these days area bunch of professional quacks... They only know how to use structural design software with the basics of structural analysis n design.

I concur with the op because most people just but houses without knowing what the developers have done as per the foundation.

Foundation is very key n must be taken with utmost care

There seems to be some disagreement amongst us the Engineers here. I'll like to state that there's no One-method to build a house especially with regards to structural detailing. We must at all times be open to learn new things, no one is a monopoly of building. Same method, same result. Different method, different result. @ OP, I still don't believe that someone can build on sandy soil without excavating, but however I was forced to study the method you stated. Assuming the foundation is properly chained with a beam there might be no differential settlement especially if the building is a bungalow or simple duplex with a negligible dead load. But I sincerely doubt that any Engineer no matter how quack will apply this method for High-rise building. What ever you do never forget the CLIENT is FIRST.

Architecture|Property Development|Complex Renovation

Engr. Daniel(07037629947)
TerraStone Shelters

COOLDK:


The main purpose of adopting a raft foundation is to prevent differential settlement.

Even if you are adopting a raft foundation, the technicality and logics shouldn't be compromised. You still need to carry out soil test/investigation to ascertain the suitability. Otherwise piling will be best here.

Piling are required in a waterlog area that u don't know the hard surface, so would drive the pile till u hit a good ground or hard surface because u can't say u want to use a pile on solid ground when u not constructing bridge

COOLDK:


The main purpose of adopting a raft foundation is to prevent differential settlement.

Even if you are adopting a raft foundation, the technicality and logics shouldn't be compromised. You still need to carry out soil test/investigation to ascertain the suitability. Otherwise piling will be best here.

The argument here is not which is d best
But situation u cast a ground beam on Sand with digging is possible..

Dannyset:
Rampant


Sir, even when you're doing raft you still have to dig to depth that would contain it before any construction.

Not all situations...
Situation u bough a land in swampy area. U fill it and leave it for over a year to settle and need to a duplex on it.. .u don't need any digging, d ground is stable

sabama007:


I really don't understand your epistle.

To start with, how many of clients carry out comprehensive soil tests?

What is the average soil bearing capacity for areas like Lekki n Ajah?

What is the preferred foundation type for such areas?

What we have these days area bunch of professional quacks... They only know how to use structural design software with the basics of structural analysis n design.

I concur with the op because most people just but houses without knowing what the developers have done as per the foundation.

Foundation is very key n must be taken with utmost care

soil test... have u ever built before? did u study construction economics.. there are codes and assumptions made wen building.. foundation foundation foundation... I don't work with structural engineers dat don't visit the site... and the op is saying this method is bad, not knowing that this method with a surrounding retaining wall as d fence with a depth of 1m can stand as any other building, Nigeria is where it is because u don't know what u read and u don't experiment and test different construction methodology other than what ur lecturers of 1980 taught u.. every building, site is unique and need different method of construction. this method is not bad soil test or not. its is a method of construction.. I am not talking of the soil

This is common among developers who lease properties for some certain amount of years.u are talking about foundation alone, their greedy knows no bound.they will use materials sufficient to build just a storey building for two storeys.though I can't detect any type of foundation. I just make my observations and findings from the sorroundings

Comprehensive soil test is just the solution to all these, the bearing capacity, consolidation and settlement of the soil will help the structural Engineer design the foundation. And the house is good to go, there is division of labour in construction work, the geologist will study the soil, the structural Engineer will design with the load putting into consideration what the soil gave,and the builder will build.

shine12:


If the weak soil is excavated to quite stronger soil at about -1.5m with better bearing pressure and then a reinforced raft can be adopted.But in very loose sand with high water table, piling might be the only option.

It also depend on the type/amount of load the foundation is to support. That's why every atoms of structural details counts during implementation.

Barselonia:

Piling are required in a waterlog area that u don't know the hard surface, so would drive the pile till u hit a good ground or hard surface because u can't say u want to use a pile on solid ground when u not constructing bridge

Even on a land that seems stable and hard enough. You can't conclude until u carry out soil investigation. What is lying 500mm to 1000mm below NGL might surprise you during excavation.
Perhaps, short piles of about 4-5m have been introduced where considered fit economically