₦airaland Forum

Before we could start the roof work, due to the complex nature of the roof, we have to do a simple roof design sketch showing all the "roof tie beams .

here is the roof tie beam sketch

here is what we are looking to achieve

Here is the house before we start renovation

I'm here again to present to you my ideas on how to design and construct an economical and aesthetically pleasing roof in Nigeria.
for this topic, i will be using one of Harney projects ( podosci and abdulwastecx) ongoing project as a case study.
this thread will try to shed lights and educate prospective home owner on how to choose floor plan design that will be pleasing in the eye, economical and will be durable over a long period of time.

case study one: construction of timber roof truss for a confidential nairalander
contractor : harney projects
Duration of roof work : nine days (including two Sundays)
Location : confidential

twinskenny:
lol i think i know what u are taking about sir...

My oga sir.... Contact me, I have a job to discuss with you sir

Dieumerci:
Culled from one of the great Aventures' classes.

Pix 1. Damp roof admixture (sycallyte) being added to the capping concrete mix.
Pix 2. Capping concrete in place to prevent dampness, used to perfect our floor level yet to come and to be used as reference point for measuring out our lintel level and other measuremnts
Pix 3. View of the capped area.
Pix 4. More view of the capped Area.

Let's discuss this with regards to it's advantages over German floor and how effective it is to prevent dampness.

Nice iniative.... The performances could be improved by adding light reinforcement of say 2Y 8mm across the wall.

Pictures ceiling work of the bungalow

Onuokwu:
That wood resting on the parapet reinforcement, is it not going to cause problems in the future?

The roof is still under construction, when the roof is completed that wood will be braced and will not rest on the polystyrene fascia

[quote author=lastpage post=39457853]type of wood Boss! My other questions too, please


Lastpage!

[/quote

Some hard wood from onto state, it is a combination of mahogany, Ebelebe, iroko, etc

lastpage:
Nice!

Well done Bro!

More power to your elbow.


Abdul, what is the name of the wood l highligted?
That circled part is used to tie down the wooden beam (I think?)
Is it Rubber, wire rope or 10mm iron? What is it please.
Another question: How do you generally tie down a roof in a multi-storey dwell? What is your prefered method?

It cant be oja'agba, right?



Lastpage!

Roof connector vary and depend on the type of roof.
For steel roof such connector will have to be design by a structural engineer but for a timber truss the method will be different.

My definition of high rise building may be different from yours sir. High rise building are building with more than ten floors and we don't actually build that high.

For a building of 3 to 6 floors, wind load will be more and a parapet or concrete fascia is needed to reduce wind speed and uplifting of the roof. The same connector can also be used.

The connected is made from mild steel and can be of 6mm. The rod is tied to the top reinforcement of the head beam reinforcement. I think that will do the job sir

lastpage:
Nice!

Well done Bro!

More power to your elbow.


Abdul, what is the name of the wood l highligted?
That circled part is used to tie down the wooden beam (I think?)
Is it Rubber, wire rope or 10mm iron? What is it please.
Another question: How do you generally tie down a roof in a multi-storey dwell? What is your prefered method?

It cant be oja'agba, right?



Lastpage!

Tie beam.
My method of connecting head course/head beam to the tie beam is using a connector made from flessible cable of say 6mm diameter.
This rod is embedded in the concrete and allowed to project out to tie the building to the roof.

This tie rode is spaced at 1.2m center to center but due to unsymmetrical arrangement of tie beams and rafter some may fall of line

More pics

lastpage:
Nice!

Well done Bro!

More power to your elbow.


Lastpage!

Thanks boss

I have done a simple cost comparison between this polystyrene fascia and in situ concrete fascia for building of this magnitude.
Here is my cost breakdown for a very good concrete fascia (summary)
Formwork:
Workmanship = N150k
Wood (2x4, 1x12, pattern wood, 1x6, 1x3) = N150k
Plywood (1/4 plywood) = N54k
Bamboo(@N200/pole) = N30k
Nail and other miscellaneous =N20ki

Total = 404k ( very optimal estimate e)

Reinforcement : Workmanship = N150k
Reinforcing bars (y12, y10, binding wires) =N150k
Total =N300k ( tidy estimate)

Concrete work :
Cement (using mix ratio of 1:2:4) = 50bags (75k)
Sand = N30k
Gravel = N45k
Workmanship for concrete work = N50k
Total = N200k

Allowance of N150k for plastering and striking of Formwork.
Total = 1.054m.

Comparing that 6840k
That is like 35% cheaper than in situ cast concrete fascia
The installation time is much faster
The weight is much lighter and design much more flexible

Here is the pipework for electrical fittings
Type : full conduit
Number of distribution board : one per flat

More pics

More picture of the dressed polystyrene fascia

Here is my finished polystyrene fascia for now

lastpage:
Right on the button Hajj!

I suspect what we are being given is an "adulterated mixture of Aluminium and cheap metal".

For the records. Aluminium cannot rust... except if adulterated.



Lastpage!

Rusting is corrosion in iron and steel product while corrosion in aluminum is called aluminum oxide.

The statement could have been aluminum also corrode but it's corrosion is called aluminum oxide

KolaShangOne:
You just talked about my concern in the second paragraph.. "Other dead loads".
Oyibo people design for worst possible scenarios. There was a high rise building which was bombed but the structure didn't collapse though a part of it was wiped off from top down.

You demonstrated that it would work for a residential but sometimes these buildings are converted to commercial property which it wasn't defined for. You understand my point Mr Wasiu?

I understand your point Mr Kola.
Rib slab is for floors with small imposed load, both high rise and low rise building.

KolaShangOne:
Alot of things have gone down here o.. Just yesterday that I missed the thread.. I was still hoping to come here and continue my discussion with Abdulwastecx about not agreeing with his calculations because it was for slab and not for beams etc..

Guess me and Abdul will continue on WhatsApp..

The calculation is for slab design load but this load will automatically be distributed to the adjoining beams using yield line or any other convenient method.

Other dead load that may also be on the beam are wall load (which can also be reduce using lighter material for partitions ) and beam self weight ( since it depends on the beam section, a smaller section means lower Beam self weight)

brabus:
Can you do cost analysis of using polystyrene for a 312 m² pent slab? I can forward you the design and calculation sheet.

My initial plan was to do I-section to reduce the load coming on the first floor slab.

yes sir.....i will do that, but you will pay me o lol

johnson232:
God bless u... I'm really enjoying this lecture. This is nice, In that case, what will the polystyrene (p) be resting on as illustrated in the diagram? Or Will it be able to support itself after the curing of the whole slab?

The section of the poly strip is design with inward depression that allows concrete to flow into it casting. i will try to get a sketch to give better explaination

KolaShangOne:
Same way it will reduce beam section weight is the same way it will reduce the ability of the beam to carry the imposed load especially on a multi rise structure

it doesn't reduce the ability of beams to carry imposed load.

for example, a simple slab with the following loading condition
1. live load (Qk) = 1.5kN/m2
slab thickness = 150mm
weight of floor finishes = 1.2kN/m( assumed value)
2.dead load on such slab( Gk):
self weight of slab = 0.15x24 = 3.6kN/m2
Gk = 3.6+ 1.2 = 4.8kN/m2
design load (w) = 1.6Gk + 1.4Qk
w = 6.72+ 2.1kN/m2 = 8.82kN/m2

summary: for a typical dwelling unit of a design load 8.82kN/m2, out of which dead loads account for 76.2% ( 6.72kN/m2).

Conclusion: dead load can be reduce by introducing a lighter materials at some section of the floor slab ( provided live load not heavy).

KolaShangOne:
It can't be used for beams.. Just the rib slab.

@abdulwastecx In terms of cost and availability of materials, which would be better to use between Polystyrene and the clay pots for reduced load on the structure? I have a feeling clay will be cheaper. What do you think?

availability of materials= clay block
cost = polystyrene
reduced load/ weight = polystyrene
speed of construction = polystyrene

johnson232:
Thanks for the lecture sir. But can polystyrene also be use for beams and slabs?

polystyrene can be use in slab ( ribbed or waffle slab), this will reduce load on beams, thereby reducing beam section (weight) and reinforcement

johnson232:
This is interesting, will the polystyrene be use as support for the concrete slab? Will it be able to withstand the load of the slab because of its light weight? Or it's gonna be use as both the beam and the slab?

Rib slab are done on floors with relatively medium to low live load ( load of occupant, furniture and other variable loads), in most cases for residential ( live load for residential 1.5kN/m2), schools, hotels (2.5kN/m2) all these details can be gotten from BScodes.

The ribs are design as small beam running perpendicular to the longer side of the slab (ly), and parallel to the shorter part of the slab (lx).
the rib are spaced at design distance ( from BS 8110), the space between the beam is occupy by this non structural polystyrene.

A concrete topping of not less than 75mm is placed on top of this polystyrene to protect the polystyrene and provide a moving surface for occupant above the suspended floor. a wire mesh is provided inside the toping to control cracking of the concrete.

i will do a sketch to buttress my point.

brabus:
You dey do Lagos? You fit do collabo? I have projects where I have freehand to sing the lead.

I've done Aluminium Parapet system, Precast parapet, and in-situ. I've also done Aluminium cladding for fascia boards. So there can always be a project to showcase what's possible to those that believes.

You've demo the product so let's work something out.

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Oga Adeekiti, don't mind the Oga up there o? I'm sure he just like playing rough play. We chatted for over 30 minutes last week discussing various things about his project and I was even giving him some advices based on my experience in the field. 99% of those who accused me on Nairaland still chat me in the background seeking advice/information. Oga mavverick, abi na lie?

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What won't happen is loosing the moniker "Brabus" or loosing the brand name "NextHome". No matter what anyone says!

I will be open to such sir....I have seen your works and i love your works and packaging. I have never handled any job in lag but will be open to the possibility of coming over for job when i am through with what i am working in now.

Thanks for the offer sir

johnson232:
Thanks for the lecture sir. But can polystyrene also be use for beams and slabs?

yes sir....it will definitely save you alot of unnecessary dead load which in turn save you iron and cement (cost).

I am still looking forward to a job i will be allowed to do the design and construction of rib slab, where polystyrene is used for the rib

johnson232:
Thanks for your response sir. I really appreciate...
Sure we gonna carry out soil tests. I just wanted to sample opinions, as someone opined that we might use those pile foundation we see on tv. Like those hotels and skyscrappers in dubai, I never thought 5 storey building would require much. I'm a novice when it comes to construction though....

that is the beauty of soil test sir. If properly done by a good soil technician and all the calculations are properly carried out by a foundation engineer (civil engineer), the specific soil bearing capacity, settlement rate, moisture contents, water level, angle of frictions, unit weight of individual soil etc up to a reasonable depth into the ground, then you will have an idea of what soil you are building on.

since building foundation depend on soil bearing capacity(and all other characteristics listed above ) and the loading intensity of the foundation ( all the gravity load on the building divide by the area of the building), reasonable calculations will have to be carried out and a reasonable foundation type ( either shallow, or deep foundation) will have to be proposed for your building.

There is also a miss conception about dry soil/ strong soil type, since these terms are subjects. A solid soil for building "A" may be too weak for "B" and soil property of good or bad cannot easily be assessed by eye investigation only since soil exhibit very complex characteristics. soil mechanics is a very complex thing to study because a strong soil in stata A: of say 2m, may be overlaying a cohesive soil of lower strength.

Also during the conceptual stage of design try to avoid too much load on the structure, if the building is to be an hotel, school, residential apartment where the live load is relatively lower. At this stage, using light weight materials to substitute conventional materials may help reduce load and cost on the building.
The largest contributor of dead load on a building is slab-beam members, if these members are made lighter using polystyrene, rib clay blocks and other forms, load will subsequently reduce on the structure

erico2k2:
What do you guys think of this hand poker

i like this small concrete vibrator

johnson232:
@bold, pls do. We are keenly waiting... That's by the way, as a SE what type of foundation would u suggest for a 5 storey building to be situated on a very dry land? To be located in edo.. Cc: abdulwastecx and to all other SE in the house...

Bro, Edo is like Ondo state, shares a lot in common with ondo on other southwestern states.
I will advice you to do a detailed soil investigation to get all your site soil characteristics, it will safe you a lot of money and risk of structural failure in future sir. thanks