casiraghi:
Thanks for the post

What could cause caving of the floor even when there is a proper German floor and the DPC was properly compressed.

what has happened to you is as a result of no damp proof b4 the concrete was poured on the floor. After the compacting of the filling sand there should be rolls of plastic sheets on top the sand b4 concrete .Hope this helps.

Gifted4all:
Must we use hard core on a pile foundation

yes, if the area is damp a little..

If the area is water-log use reinforcement

jejeman:
Pls does a room size of 3.35m by 4.23m needs a beam across it centre apart from the beam on the surrounding wall?

not really, beams are required in spans of 4.5m and above

manwonder:


Yes, I thought of that too, but working during the rainy season has now confirmed my initial fears that I might really need to reinforce the foundation. Initially, what I was told was that I would only have to do normal foundation, and that at the worst, it would need a german floor (many people, including my bricklayer, were saying this). But from the look of things now, I might need to do much more than that. I have a feeling I might need to make the blinding as thick as 150mm, and also do a raft, but I need professional advice on this since I don't know much about these things.

whether you build in dry season or rainy season, it doesn't change the fact that the area is waterlogged,u r even lucky u discovered the area is water logged before casting the foundation.

I will advice you use reinforcement or hardcore for your foundation, whether in dry or rainy season because that area is water logged.

You can also do some sand filing and compacting.

opalu:
I have been involved in the structural corrections of more than 1,250 buildings that were wrongly built in the past 10 years.
In all, I have discovered the major reasons why buildings fail structurally are
1. Lack of professionals on the project. The some sub reasons that owners give are that they don't have money to pay them since their charges are avoidable. And also that they themselves have ideas about buildings etc. When there are no professionals on the project, such project will not have the necessary CORRECT designs/drawings. Such projects won't have the right professionals Supervising the Construction Process.
2. Another major reason for Structural failure and foundation issues is the use of substandard materials. These include reinforcements, Sharp sands, Granites, Cement even Water etc. So many Rebars being used can easily cut or rust. Water that contains impurities is not safe for concrete a since those impurities attack the concrete. (Chemistry 101). A Man wanted quote one day and I gave him. But he went for one desperate Contractor who used filling sand to cast concrete! After 6 months, the suspended slab (decking) started vibrating like water bed. I was also called upon and i corrected it at a cost 3 times the cost to build a solid slab. In addition, using the same size of granite (coarse aggregate ) can weaken the concrete.
3. Another reason for failure in buildings is the use of wrong methodology in construction. For instance there is a method whereby wet concrete is vibrated in order to expel voids and holes inside. If you are using pole vibrator, it has to be poked into it left in there for brief interval and removed and poked somewhere else. Some quack roadside casters just use stick to shook here and there or hit here and there. Even if the vibrating machine is used wrongly, it will trap voids. Every construction work has best practice that if not followed, the result will be bad. Another example is that when a carpenter lays the 1x12 for first floor slab, every hole between the planks must be covered with well sliced cement bags nailed with tiny nails. This should be done before laying of reinforcement. Reason being that when casting is done, the wet concrete usually slip through those holes thereby weakening the lower part of the slab which is subjected to tensile stress. But due to the leakage of the concrete at that bottom, what plasterers usually do is to fill it with mortar before plastering suffix of slab. But don't forget that the reinforcement were exposed before. So structurally, the bottom reinforcement is nonexistent. So when there are tensile forces, the slab cannot withstand them and what do you get? CRACKS!!! Then your fine POP starts cracking, blocks starts detaching at first floor and even crack etc.

Let me stop and await your questions.

nice thread opalu .Although im an architect and a contractor this tread is also useful to me too nice job keep up the good job we are following.

kloser:
Please should one be worried if the compound i.e the play area and car park of a building gradually sinks and detaches from the main building but the building itself isnt sinking at all,note-the foundation of the building is piling

differential settlement. Op pls explain better to him. As for me, I still dey find work.

talk sence wen u talk of employin ppl! rubbishness!

austin2all:
Good job bros, pls my question is this: how much will it cost to build a block (2 storey) of 4 flats of 2 rooms and parlor, kitchen, on a dry land. Putting into consideration the current prices of building materials in the Nigerian markets.
Thanks for your anticipated reply.

If you have the architectural drawing, I will give you a near perfect quote

erico2k2:

what has happened to you is as a result of no damp proof b4 the concrete was poured on the floor. After the compacting of the filling sand there sold be rolls of plastic sheets on top the sand b4 concrete .Hope this helps.

Thanks bro. That is the answer.
DPM is Damp Proof Membrane which is locally called Nylon. It has to be laid on the floor area before blinding before reinforcement work. Some persons prefer to lay the nylon on top of the blinding while some lay it directly on the hardcore.
The main essence is to lap the nylon rolls so that moist doesn't rise to the floor and spoil your tiles and wardrobe

Tjhamman:
Opalu
I have a bungalow in the the village which I intend to convert to Duplex. My question is, is it cheaper to demolish the Bungalow and erect a Duplex or erect 15 -20 concrete pillars and build the first floor on top of the Bangalow. I really like the design of the Bungalow and will not mind to have top floor to accommodate my family. The second question is will it better solid enough and not to pose a danger.
Tj

You can convert any building into any building of your choice. Simply use the right professionals who know their onions.l
All that a Structural Engr will need is the architectural of the existing structure and that of the proposed structure. Infact if a good architect does the architectural, the new upper floor will not be too complex in the circumstance.

adonismuller:
not really, beams are required in spans of 4.5m and above

Many thanks

by semitunde:10:52am



You didn't state your own design depth and the no of storeys of the building or type of building. This would have helped more in forming a discussion.

Why didn't you reduce to 750mm as the client wanted? Is it because the building cannot be designed with such depth? Or because you need the building to be above the flood level as you say?

What parameters did you use to design the foundation to take care of the flood? Can you take us through the process?

Thanks

I used 225x900mm deep raft
The reason why I didn't use 225x750mm raft was because the Geotechnical report I worked with for that site showed me the subsoil strata. Besides 75mm depth was inadequate based on my structural analysis

In terms of the flooding, water flows to the compound that has the lowest level. It gets worse if a compound is lower than the connecting road.
So what I did was simply to raise my site level above the road level to a point that cost won't be outrageous.

pls can u teach me how to estimate building material for building construction,am a civil engineering student

how much will it cost to build a 30 room self contain in a 3 storey building setting?

manwonder:
OP, God bless you for creating this thread. I had just created a thread on foundation and structural issues 3 days ago, wherein I was seeking professional advice on my building project as I didn't just want to rely on my bricklayer's information.

I'm about constructing a 3-bedroom flat en-suite on a half-plot of land located in an area where plaster sand (called Dagbolu) had been excavated. However, my concern is how to go about the foundation, as I noticed that the the area that my bricklayer had dug became water-logged and almost got washed off as soon as it rained, which gives me the impression that the foundation would need more reinforcement than normal.

Therefore, I need to know the following:

a.) How to go about laying the foundation

b.) What materials would be needed in laying the foundation

c.) How much it would cost to lay the foundation according the method(s) suggested in (a) above and considering the materials suggested in (b) above

d.) How much the whole construction from foundation to roofing would cost considering the nature of the land and the building plan

Please find below pictures of the little work done on the land, as well as the building plan. The land is located in Oluodo area in Ikorodu, Lagos.

A. The foundation for bungalow is not as critical as that for a storey building. In as much as I don't know the sub soil situation, I will also be interested in determining the suitable compound level for the site. There was this Joint Venture our company wanted to embark upon at Osapa. The owner had developed two luxury blocks of flats with good foundations but without caring to find the good datum level. Therefore when Lagos state constructed the road, the road level was at the ground floor widow level of the 2 multistory buildings. Therefore just a single rainfall fills the compound like a swimming pool. It doesn't get dry before the next rainfall.
So back to your question, you can use Reinforced Wide strip foundation of short raft. The reason is to tie the entire foundation so that they act as a single unit.
I have used smaller pad foundation for bungalow due to the nature of the soil. There are things an Engineer can see by site visitation that pictures may not cover.

b. The materials are granite, Sharp sand, Cement and Water. You are add some reinforcement depending on what your Structural Engineer on Site advises.

C. & D. Send me your email

Pls sir,do you have idea on pile foundation?

Eragablessen:
Bless you op for a demanding thread like this. I've bought a land but plans to start my building by Feb. 2016.
The structures i hope should include 3 bedrooms, 2bathrooms and toilet each, 1 living room/kitchen, 1 dining room, small utility room and a gym room. I also want a "p.o.p" bent on the living room. Please do you have any idea on how i should go with the plans so as not to avoid architectural errors Thanks.
Modified, its going to be a flat pls...

Give it to an experienced architect. If you don't have I can give it to someone reliable to do it for you.
But why wait till 2016 when you can finish the building before 2016? Best of luck any ways

Adewunmismith:
Pls sir,do you have idea on pile foundation?

Yes I have done thousands of piles for different buildings.
What aspect of piling do you wish to know about?

joshua112:


nice thread opalu .Although im an architect and a contractor this tread is also useful to me too nice job keep up the good job we are following.

Thanks sir

Myself2:


Are you guys mad? They're discussing something as critical and important as the above and you lousy lot are busy rambling about first to comment.Jeez, so irritating

sorry sir... i meant no harm

algorithmz:
Op what is the most cost effective means of correcting cracks in buildings also how is the flow of moisture in buildings corrected.

When there is a crack problem, the Structural Engineer is like a doctor that will diagnose the remote cause of the crack.
If it is a Structural crack it will be treated structurally by adding concrete element in the appropriate place (s). The treatment it will be given is consequent on the findings of the professional involved. So I cannot sit and give a gbogbonishe solution to all structural cracks.

For the rising damp issue, someone has answered that very well

opalu:
There is a vital aspect of using inadequate foundation. The determination of the type of foundation a building requires is done by the Structural designs matched with the Soil Investigation/tests. The Structural Engineer through his Analysis estimates the entire loads that is coming on the foundation at various points. Where the foundation required is raft, he determines the depth that will be both SAFE and COST EFFECTIVE. But in a conflict between safety and Cost, the safety takes precedence or else the architect is called in to redesign the building to make it smaller/lighter.
Last year, I did an entire structural designs for an estate at Elegushi in lekki. And the Owner insisted I reduce the raft to 750mm depth. But based on my designs, 750 depth will fail. So I didn't. By the time they the foundations were done to my standard, as soon as the ground floor slabs were completed, heavy rain fell and the ground floor of many estates around the site were submerged, all the ground floor of all his own estate were not flooded.
That was when he knew I did a good job for him.
Apart from flooding, the ability of the foundation to carry the dead and imposed loads for at least 100 years is what is critical.

Nice one OP. That's a superb service you delivered. Pls, I'd like you to 'briefly' explain to me how you go about your raft foundation analysis. Which principle do you use? Which software(s) do you use in your analysis and design? I'm so sorry if I'm deviating from the main thing, but it's all about getting a good job done down there... Nice section... Thumbs up.

opalu:


Yes I have done thousands of piles for different buildings.
What aspect of piling do you wish to know about?

thanks for the response,i want to know the best pile foundation that can be used for structures in waterlogged areas like lekki,ajah.

Eragablessen:
Bless you op for a demanding thread like this. I've bought a land but plans to start my building by Feb. 2016.
The structures i hope should include 3 bedrooms, 2bathrooms and toilet each, 1 living room/kitchen, 1 dining room, small utility room and a gym room. I also want a "p.o.p" bent on the living room. Please do you have any idea on how i should go with the plans so as not to avoid architectural errors Thanks.
Modified, its going to be a flat pls...

worry not.....ur worries should be getting a good architect who understands ur design functions.....call 08068030834

Adewunmismith:
thanks for the response,i want to know the best pile foundation that can be used for structures in waterlogged areas like lekki,ajah.

The major characteristics of piles are the pile diameters, the pile depths and the pile groups. And we have two types of piles commonly used here. Driven piles and In situ piles.
The characteristics and the types are determined based on the kind of structure coming on the foundation and the nature of the soil.
I once did some piles at a riverside near Agbowa after Ikorodu. The piles were average depth of 30m. For a load that is like a single storey. But a Kilometre from this site has good soil that won't require piles for such a superstructure.
In a place like lekki, there are areas that a 6 storey will require 30m depth pile. Some sites will require far less depth. Some will require far more. So piles are not 1+1=2. You run the necessary tests and analysis.

Great information op. Thanks for this helpful thread.

alchemist:
I just prepared a BOQ for a client and i noticed they used 1500mm for the dept of grd beam (raft foundation). The structural eng in my office said its too much that 900-1000 would hold the one storey building. The building is located along ajah expressway.

What is your take on this as have been trying to convince the client to actually save cost.

Bros I won't be able to condemn or advise against what my fellow Engr has done except I have all the details he worked with.
But I have built a single storey in Awoyaya and I used 1800mm depth.

ADAMUdaCOWBOY:
Impressive thread. OP I want to build a bungalow on a rock, how do I go about it?

To build a house on a rock is a nice one.
I would have loved to see the picture of the site to advise properly. For now I can give you a skeletal advice.
However the type of foundation normally used is solid raft. That means you have virtually horizontal plains where will form the ground floor. Sure there will be some cuts and fills here and there (if possible).
Then you panel the ground floor using reinforced solid raft over rock. I will look for a picture of how this is achieved.

Nice thread to follow.. Thanks Op.

opalu:


The major characteristics of piles are the pile diameters, the pile depths and the pile groups. And we have two types of piles commonly used here. Driven piles and In situ piles.
The characteristics and the types are determined based on the kind of structure coming on the foundation and the nature of the soil.
I once did some piles at a riverside near Agbowa after Ikorodu. The piles were average depth of 30m. For a load that is like a single storey. But a Kilometre from this site has good soil that won't require piles for such a superstructure.
In a place like lekki, there are areas that a 6 storey will require 30m depth pile. Some sites will require far less depth. Some will require far more. So piles are not 1+1=2. You run the necessary tests and analysis.

,thanx for the enlightenment sir, I am a fresh civil engineering graduate ,thou I have not witness any structural construction using piles as the foundation.

opalu:


A. The foundation for bungalow is not as critical as that for a storey building. In as much as I don't know the sub soil situation, I will also be interested in determining the suitable compound level for the site. There was this Joint Venture our company wanted to embark upon at Osapa. The owner had developed two luxury blocks of flats with good foundations but without caring to find the good datum level. Therefore when Lagos state constructed the road, the road level was at the ground floor widow level of the 2 multistory buildings. Therefore just a single rainfall fills the compound like a swimming pool. It doesn't get dry before the next rainfall.
So back to your question, you can use Reinforced Wide strip foundation of short raft. The reason is to tie the entire foundation so that they act as a single unit.
I have used smaller pad foundation for bungalow due to the nature of the soil. There are things an Engineer can see by site visitation that pictures may not cover.

b. The materials are granite, Sharp sand, Cement and Water. You are add some reinforcement depending on what your Structural Engineer on Site advises.

C. & D. Send me your email

I just sent you an email; please check your mailbox. Thanks.