₦airaland Forum

EgunMogaji:
Azuh, this is like putting lipstick on a pig.

Of course you know I'm joking. Carry go, nothing do you.

the two structures doesn't really look alike... i am waiting to see the magic that was done to that house

mavverick:
Very nice piece of work here, great to see that not all the contractors/Engineers/Middlemen on NL are scammers. Some do take pride in what they actually do, and its very good to see that.

just one question Abdulwastec, I only just saw the thread today after a long while, there is a pic with some 4inch waste and 2inch pipe on the surface wall, could this have been hidden ? I just find that sometimes pipes can be a eyesore, and divert the eyes away from outstanding work.

thank you for your complement sir... with respect to your question, we had a limitation of what can be conduit because of the age of the house, construction type and size of block that was used for the upper floor.
The building is built with load bearing walls without beams, chiseling the ground floor 9'' blocks to insert our plumbing 4'' and 2'' pipes may be detrimental to the building structural integrity.
The building is almost 30 years old (from a reliable source) this limit the rate at which we can chisel the building to put large conduit pipes
The upper floor is completely built with 6'' solid block, it will be impossible to chisel such block and insert a 4'' plumbing pipes.
All these aforementioned reason necessitate for the use of surface plumbing pipe. These pipes will be covered with some fancifully made aluminum panel .

lastpage:
I suspect what you have in mind is not what we are referring to?

Conduit purposes? YES!
Weight Reduction? NO!


As Abdulwastecx has shown, the thing involves a lot for Engineering calculations to avoid 'failure' of the Concrete involved.

I am just imagining, if l could eliminate about 40% total weight from a building, that building could / will float on a soil it is assumed not to be capable of floating on, without expensive Foundations like inverted raft, Piles, e.t.c.

That could be like #7Million+ saved, for a two storey building

Thanks for those pictures,l gbadun them.



Lastpage!

you are right sir... i am also on the same page with you on the amount of money that can be saved if we use some modern method of building construction.

one major weight contributor to residential reinforced concrete structure is the "suspended slab and beam ", if this slab concrete section can be reduce, the weight will significantly reduce and dependent members like column, foundation footing will be reduced drastically.

I will highlight some of these construction method that can be changed a little bit to reduce cost.

1. isolated footings, combing footings or continuous footing and strip footings can be changed to on isolated/combine and continuous footings with grade beam, this will eliminates the need for sub structural work in most cases. the foundation wall for bungalow or one storey building only provide lateral brazing to the foundation columns and sometime help to carry ground floor wall. instead of building 1.8 meters (six couches of blocks in most cases) that will run into millions, the foundation column can be design as unbrazed column with fixed joint at the pad surface and DPC level. A grade beam can then be introduced on the ground surface with sufficient depth to links the foundation column, provide top restrain, carries the foundation wall and carries the DPC.

lastpage:
Thanks to you and Brabus, for shedding light on this practice.

In my own opinion, l believe "Construction" ...is a SCIENCE.
Thus, l know that Engineers just dont decide 'randomly', on how many pipes to put, where to put it, size/thickness of pipes to put, e.t.c.

What is the Equation/Formula or "Scientific guiding principle" in this sort of practice?
Does anyone have a handle on such scientific formula?


I am thinking that we can save a lot of cost, even use less costly foundation and build on not so solid soils, if we can limit the weight of out Slabs, columns and beams..... while not sacrificing structural integrity.





Lastpage!

The scientific quid is our BS codes and Euro code couple with basic understanding of structural analysis and design.

lastpage:
Thanks to you and Brabus, for shedding light on this practice.

In my own opinion, l believe "Construction" ...is a SCIENCE.
Thus, l know that Engineers just dont decide 'randomly', on how many pipes to put, where to put it, size/thickness of pipes to put, e.t.c.

What is the Equation/Formula or "Scientific guiding principle" in this sort of practice?
Does anyone have a handle on such scientific formula?


I am thinking that we can save a lot of cost, even use less costly foundation and build on not so solid soils, if we can limit the weight of out Slabs, columns and beams..... while not sacrificing structural integrity.





Lastpage!

Very good question, there are design guide that one can follow to design ribbed slab.

For a lighter rib one can use polystyrene pod instead of the sancrete block or clay block.

Check out this ribbed design calculations done by me some years ago.

DerrickM:
Thanks for your observation but you are totally incorrect. If that's the only way to make yourself feel relevant in your field that's your headache so do your thing. I did structures it was based on mathematics,further mathematics & physics. You unfortunately couldn't break it down to the correct components of what makes it up. What an irony.

I don't really have your time Mr architect but I am very sure you can't even do a simple continuous beam analysis using stiffness matrix method

markemordi:
Note: Most civil engineers don't face their own line of construction you will see a civil engineer doing a builders work...... Let civil engineers focus on highway designs and
construction, geotechnical and water resources which is their specialization....
Architect is meant to design and not to build..... Nigerians believe they have degree relating to construction they can do everything ie be an architect, builder, structural engineer at the same time......

you are not making any sense oga.... civil engineering is sub divided into structures, highway, water resources, geo, foundation etc. most if us do building work because that is what is common

hardywaltz:
I believe I had answered this question.
UniBen offers Structural Engineering as a course on Jamb form (From Yr 1) not an option under Civil Engineering like most other schools.

No university offers engineering course from year one.
for a five year degree program you have the following
year one : advance o level courses like maths, physics, chemistry, statistics gst etc
year two: general engineering foundation courses like Eng maths, material science, fluid mechanics, applied mechanics, basic electrical engineering etc.
year three: general civil engineering courses like strength of materials, advance mechanics, eng maths etc

DerrickM:
Part of why I decided to learn structural drawings from a fellow architect not an engineer. Even the guy I assigned to my uncle's building site messed things up with his drawings after that design I stopped using him. He's been bugging me for new jobs but in his dreams forever for real...#okbye

From the way you talk, you no so little about structural design. structural work is more complex than what most of you guy see on paper. you just don't learn structural drawings without basic and advanced knowledge of mathematics. structure is 100% mathematics, you cant just learn it without an engineering degree

twinskenny:
Thank you everyone God bless

Congrats Boss

EgunMogaji:
Strictly from a Nigeria building scheme of which I am not an indepth expert.

The side support is of extreme importance, can't be of the weak shyte blocks that is common, so has to be reenforced poured concrete. Added cost.

The good thing is that once that is done, and limited to span, then the slab can be completed in a few hours and immediately ready for loading.

I've watched many episodes of Grand Designs where this type slab has been used.

Here's a variation being used in Ghana
https://www.youtube.com/watch?v=Bmu2QrkVSxk

I'm not a builder and I yield to the "real" builders.

This is a rib slab with precast rib beam. The hollow block are made to have some minimum strength.

It is very cost effective because you eliminate lots of formwork and concrete section

More updates

ahf:
Can u estimate how much surface area is saved with this slant roof over the pitched roof in Sqm?

Yea.. . Almost 30% reduction in Sqm

More updates from anambra mansion

Tboyq:
Why the black water proof before the slab casting?

you mean the damp proof membrane (DPM) before the casting of the foundation oversite concrete or DPC? it help to prevent moisture from rising through the foundation.

mebad:
Your numbers are off . can i have a consistent line i can reach you on ?

08169492682 or 08022930715

Built2last:
The north sees southwest muslims as second class muslims.

come to Abuja and see how many Yoruba mosques exists.

I leave close to one in Wuse 2.

got talking with Abdul a core muslim from Kano one afternoon on Friday, he said he was going to mosque and wanted me to shift my car.

I said shift my car when the mosque is just down the road.

He said he cant go to a Yoruba mosque....I said whats the ish with it. He said he just cant go there.

that thing puzzles me till today.

In fact I keep wondering why we have Yoruba mosque in the first place.

that is segregation

can any core muslim educate me please. why are Yoruba and Edo muslims very civil

The problem is religion become dangerous when it is mixed with politics...
Religion become toxic when practitioners are ignorant, uneducated, poor and sentimental..
I am a South western Muslim born and brought up among northerners, I can relate to your post very well.

Some of those guy you mentioned see themselves to have better culture and faith than other Muslim because simply they are hausas/fulani while some are has open minded as any southwestern or Edo Muslim.

The problem is too many jobless, arrogant and illiterates people live in that region

olapluto:
Talking juju when you are fasting....Takulah!
Talking about fasting, do people notice drop in productivity with workmen who are fasting? Or is it the opposite?

Fasting a game killer for construction workers o.. Even for supervisor like us na so so sleep we dey do.

This is a bad time to do digging, casting or any high intensive labor work

skelefish:
dont digress sir... SCOAN building collapse got nothing to do with this.
6" blocks are used from foundation to head level for bungalows.
solid 6" can also be used for storey building, but it must not be hollow. any renowned engr can attest to this. so the way u say using 6" block for foundation is wrong is specious...
u should be specific.

6'' solid or hollow may not be ideal for a duplex or storey building because of our method of construction.. .. We safe ourselves the stress of eventual problem by spending N20 more on block

lastpage:
Thank you Hajj M and Abdulwastecx!

I am referring to Head Courses!

From the post of AbdulWastecx, l guess they are important and serve a very important purpose of EVENLY DISTRIBUTING WEIGHT of the Roof, on the sandcrete block Walls. That answers my first question.

Now to the next stage, which is where the post of Hajj M, (up there) comes into play!
I always like to learn and like even more, to REFINE METHODS that are already established.
I believe that we can always improve on what we already know, by trying newer methods.

Such improvements will be guided b[/b]y
1.) Achieving the "set objective"
2.) Doing it in a way such that it costs less, it is safe (or even safer), faster or less-effort consuming.

My own suggestions were to "save on Materials used .. and thus, overall WEIGHT" (Just like Hajj M), [b]but by ensuring that the mortar or concrete mix, is PREVENTED from falling into the Holes.

Hajj M has come up with a brilliant suggestion involves not actually putting the "Head Course" on the whole SandCrete Block layout.
Hajj has proposed we just do it at intervals.....while putting tie-rods into such intervals (l hope l comprehended you properly Hajj? ) to hold the roof beams.
This will definitely save on materials and weight (as we completely avoid most of the Blocks).

But Abdulwastecx has pointed out that we would be putting excessive weight of the Roof on such Blocks that were filled with mortar mix since they would form POINTS where the weight of the roof will be acting downwards upon.
he reminded us that our Blocks are not that strong.
I agree 100% with this observation.

Now, l am thinking there is a way we can do what Hajj M suggested, while achieving What AbdulWastecx has in mind, and at the same time, achieving our objective:

What if we do what Hajj M suggested, not on the blocks but on the Column points such that the weight of the roof does not actually lie on the SandCrete Blocks, but on the reinforced Columns which are designed to carry such weights, from the onset.
Excess iron (allowed deliberately during iron-size cutting for the columns) is then used to tie-down the Roof beams
Wherever the Columns do not fall at locations where Beams overlap or meet, we can then use Hajj method on the Block at that point but just in a "supporting capacity" to the ones done at the Columns!
Further-on, we can further reduce loads by ensuring that the filling of the blocks in Hajj's suggestion, doesn't go beyond the last two blocks levels, by blocking those holes, at that level, with the Cement Bags!

I kind-of think it is a good practice to block those Holes (prevent Rodents like Lizards, Cockroaches, rats, e.t.c) from finding a place to live or hide in the Block crevasses.

In summary (harmonising the different suggestions),
1) use Column-points ONLY to serve as "head course" anchor points for the Roof Beams (They can hold the weight conveniently)

2.) Add additional Head Course points, if necessary, using Sandcrete Block Holes filled to a limited depth (using Cement Bags to limit the depth) with Mortar and protruding 8mm iron or tie- rods.

3.) Block all "unused" Sandcrete Block holes with empty Cement Bags.

What do you guys think?
I have learnt something new from the two of you today. I will definitely implement these "options" in a few weeks time when a project l am doing (but abandoned due to time-factor), will get to that stage!

Thanks for your response.



Lastpage!

Very good analysis and taught provoking one at that... The column option is not practicable because in most residential houses columns are spaced at minimum of 3m center to center accros the exterior walls where this roof rest and having it in mind that roof truss are generally spaced at 1.2m center to center, this will leave so many roof truss out of line (unless we are using iron truss).

We can also provide a very thick wall plate to span between these column but this wall plate will be under considerable bending and shear at point where the roof loads act on them, thereby necessitate for need of a very thick wall plate which may be expensive and contribute lots of weight to the building.

Ways to reduce cost is to reduce the section of the concrete of the head course to 4'' instead of the normal 9'' and to use nominal reinforcement like 4 y8 instead of 4y12, the mix ratio can also be reduce

mufutau55:
@Lastpage
How about just blocking every other or three blocks holes with concrete mortar and embedding two pieces of short 10mm iron rod inside and when the concrete is ready the rods could be used to tie down the roofing wall plate. Filling every other three blocks will surely save money and weight. Hope you understand my explanations.
Something like that was done on my project with parapet and roofing preparations. I will see if I can find a picture and attach later.

Hajji M.

This method will expose some of the sancrete block to direct point load from the roof truss, knowing that these sancrete blocks we use here have very low strength (less than 1N/mm2) such point load may causes cracking of the wall in the long run.

lastpage:
Its just a suggestion l made, many other people like Madam gabby also made valid contributions to the idea.
And l am delighted that YOU have taken the "bold step" to make it a "reality".

I hope the owner grants permission to allow us follow it as you go along, ...even if it is just showing ONLY the Roof-part of the building (while cutting-off all the lower parts to prevent identification.... l respect people's privacy a lot )

Being "harder' to do .....will diminish with time, as you gain "experience" in doing it, over and over again, refining your technique and generally "advancing" your methods.

We learned something.



Lastpage!

I was wondering on something else!
One of those "money-saver" ideas you get before dozing-off!

There is this capping granite/mortar mix that is put on the last Block-level in a building.... on which you place the roof "Wood Beams".
Questions:
1.) Is it necessary and compulsory? What are the advantages if used, ...and disadvantages, if not used?

2.) Hollow Blocks tend to swallow a lot of Mortar/Concrete mix as you try to lay the mix on it (bricklayers usually use "broken blocks" to fill such holes, to prevent the Mortar from falling into the holes of the hollow-blocks.

In my own opinion, doing this adds to the weight of the building .... but does not really contribute any structural strength to it.

So, l am thinking: What if l can use the Cement paper BAGS to block this holes.... and then lay my Mortar or Concrete Mix on it (Just the topmost holes, while avoiding it crossing over to where you have the Block-body itself)?

That way, l am thinking one would have:
a) Saved on the cost of the broken Blocks used to fill the holes
b) Reduced the overall weight of the building
c) Achieved your aim of preventing the mortar from slipping down into the Block holes
d) Put the Empty Cement Bags to good use instead of waiting for Mallam to come and pack them off!

Does this make sense or am l just being silly again?




Lastpage!

You are talking about head course I guess... Every building should have that '' concrete layer with light iron embedded in them at interval of 1.2m to tied the roof truss to the building and also to help distribute load evenly to the blocks below.

The weight of this head course is not that signifantly high and the amount of money saved is not that great when one consider the structural implications of this head course beam

Chinom:
All these Yoruba people are always looking for who will help them. Always begging for help. That's because they lack proper network and the wicked nature of their people. An Igbo guy with a first class degree from the UK will get a job, even if it's with one importer at Alaba-Lagos ,Aba, Enugu or Abuja. This is because the trader will like to brag about having a first class degree holder working for him. He may not earn much, but it will be a good start. It's still better than doing 'Agbero' at the motor park.

Networking is the key and Igbos can network very well within themselves.

Must everything be about ethnicity? I agree with you that igbos have more network because of their entrepreneurship culture, I was in the east and was baffled by the high level of development in the informal economy. State like anambra have so many traders and small scale business holder than the whole of North central and one can see how much less dependant they are to federal government or white collar job.

Lack of adequate skill is one of the major problem and reasons for massive unemployment in Nigeria. Modern day educational system train people that can work but not those that can create job

desertboom:
Create Job, create job and create job. How is he going to create the job? A hungry man that can't afford just N2,000 to pay transport back to his base.

No be person wey don eat dey remember to give hungry person.

He can create job... Out mentality of searching for white color job has blinded is to opportunities around and people fail to see that these jobs are not enough to go round.

I was a first class civil engineering graduate and I created a small job with a friend through the help of nairaland immediately after my NYSC, now we have more than 10 people working with us directly or indirectly.

Bigger degree should mean bigger brain processing power and ability to see opportunities that average people can't see. First class graduate from a British school should have what it takes to compete and create opportunities for less fortunate Nigerians

segcymoor:
Sir,
Like I said earlier the foundation for this particular structure is being designed as raft (although soil test does not conducted but based on normal approach in Lekki environ.However, I personally observed need to raised the level and with the observation of soil textures within the vicinity hence consider a footing for the raft.

Here is the method:
Having allows the filling to settled naturally, we did concrete blinding to received the raft footing (In form of pile cap)the dimension is 900x900 with 16mm on all the required columns has indicated in the structural details. The columns is being married with the raft footing .This process required attention because all the columns need to be carefully align.We filled up after casting of the individual raft footing.

Having compact the filling with machine, we then blind all the trench for proper raft. Our intention is to filled up after casting the ground beam with necessary normal raft foundation approach.




______________
I will send more pictures later!

A detailed soil test would have given you a better idea of the engineering properties of the soil, and such test may cost less than 2% of actual construction cost.

This approach is not advanced form of raft, it is still a simple grade foundation (which people like to call raft here on nairaland). The truth is any foundation built on the grade in a Sandy terrain like lekky will always settled no matter what

KingEbukasBlog:
This is not the answer to my question . Is Mao a good or evil man

Mao is a good man that want to developed his country and he was successful in building a prosperous nation

segcymoor:
Not pilling though...

Very nice job sir, how deep are those columns (pillars)? what are the center to center spacing of the foundation columns(pillars)? Are the foundation pillars founded on an isolated pad footings? How deep is the perimeter beams? Are you planning to you planning to filled the void spaces between these beams with sand before constructing the damp proof course (over site concrete)? Cost comparison if the dpc of oversite concrete is completely raised an decked as a suspended floor to filling the foundation before constructing the dpc/oversite concrete.

This is not a raft foundation but beam and slab on grade foundation because of the method of design and construction.

Method of design.
1. A short pile is design as either end bearing piles or skin friction piles depending on the location of strong soil strata. If the position if the strata is economically closer to the surface, an end bearing pile is used otherwise skin friction is employed.
Alternatively, an isolated pad can be founded on a good soil strata below the natural ground level ( not greater than 3m (10ft). The foundation columns are then designed as a N unbraced column with slenderness ratio of not greater than 10. Both ends of the column (point of contact with pad footings and point of contact with perimeter beams) are considered to be fixed in connection. The analysis is then carried out to determine the amount of steel and section required to transmit load adequately.

The grade beams are designed like every suspended beam independent of the grade soil on which it span. They are designed with loads from the ground floor DPC or oversite concrete, self weight of the partition walls on the beams and self weight of the beam. The beam then transmit the load to the foundation columns.


The dpc or oversite concrete is designed independent of the grade soil or filling soil, they are designed as a suspended slab carrying service load of occupancy, furniture and it's self weight. This slab is designed as a normal suspended slab with gravity load action game downward making the middle portion of each panels to be in sagging (positive moments ) and the support to in in hogging (negative moments). This slab loads are transferred to the beams.

Here is a simple mode of load transfer
Floor slab to grade beam to foundation column to isolated pad footings to soil strata below.

But for a raft foundation, mode of load transfer is
Raft slab to soil strata or
Raft slab to soil strata and beams to reduce punching in areas with high concentrated load (places of columns/pillar position)

I am currently working on some job... Luckily, I will be doing both the structural designs and actual construction. There are some cost saving structural layout method I want to use for this particular duplex, this method involve the use of over hanged beam to have a lower bending moment on the beam.

A complete isolated foundation system where the foundation for the completely framed building will be pad footings without strip to carry foundation walls. The pad will be located at a depth with adequate bearing capacity to carry the building. Foundation columns design as unbrazed columns are then raised up to the grade, which is then linked with grade beam of 300mm wide and 300mm deep. Walls are then raised on these grade beams to have the desire dpc or ground level of 600mm.

This method of pad foundation is more cost effective than the conventional pad and strip footing foundation, it is more structurally sound and also faster.

EgunMogaji:
It's an extremely good place to learn.

Welcome to your Sister.

Tell her I'm eating "ebure" already so she misses out on any more Egun theatrics

We are learning much from you sir.. . Keep them coming baba

Completely framed structure in Nigeria have problem of lack of proper binding between the adjoining partition walls and the structural columns because these columns may be too smooth to properly bond with the wall. Thus problem can be rectify by attaching an iron binder to the column before laying the blocks.

lastpage:
If l may suggest, what about just doing the "inner partitions only" as 6" Blocks (as against all walls), while using 9" for the Perimeter Blocks?

I have done this in the past and it allowed my build to conform to the specified codes of Column/Beam size in majority of the places where they are required... even as the 6" 'inner partitions' are not load bearing as you observed.



Lastpage!

That is one area where we need serious research. Cost of building carcass can be reduce greatly by building with lighter weight partition walls. Light partitions walls polystyrene, rice husk arsh blocks, light weight concrete wall, stud and plywood walls can help reduce dead load on slab, this will significantly reduce the load on slab, beam and columns. With lower load, a smaller section of structural components can be employed, thereby, reducing cost of cements.

I like the idea of working with architects on project to reduce cost of carcass construction. Things like grid system can play a big roles on cost of construction

Barryton:
to engineers and everyone in the house. of what advantage it is doing a framed structure, i.e using only pillars and beams before placing blocks and doing the normal pillars and block setting. i really want to know if can use 6 inches block in place of 9inches for a duplex adopting the frame method. thanks all..

Frame structures in Nigeria can be constructed in two ways, namely; building the block first by allowing spaces for the columns or pillars before casting the columns (pillars), beams and slab. This method of construction is more cost effective than the second method. This method is only suitable for a small residential building of bungalow of storey to two storey building, it is not advisable for higher floor building.

The second method involves the construction of all the frame formwork (for columns, beams, slab) , casting of all these members, curing, allowing for setti and full gain of strength for a minimum period of 21days or 28days as the case may be and finally striking (removal all formwork before building the partition walls which are completely non load bearer.
This method is more expensive than the previous method but gives better strength and neat method of structural work. This method should be employed for building bigger than one story building and above (note: it can also be used for a bungalow or one storey building if the client can afford it).

6 inch blocks can be used, only that it will create recesses on both side of the wall because according to bs codes, a minimum column cross section for a building with suspended floor is 225mm (9''). The design can be done with these recesses in mind to allow for the use of 6'' blocks