₦airaland Forum

oyb:
my questions would be on M&E -

have you done a hydrological survey to determine the best point for a borehole? a few years ago we ran into serious trouble [in one of our isheri sites] when the newly done borehole in one of our newly renovated facilities dried up. thats when we found that that part of isheri has serious water table issues. we must have drilled three boreholes before we eventually got lucky.

where is the closest 11kv HT line. if you have money, it is always better to get a dedicated transformer [30-50kVA] and connect to HT. if you connect to the utility LT lines you will be subjecting yourself to 'low current' , power surges etc [often generated by inconsiderate neighbours connected to the same transformer feeding the LT line]

do you have your m&e drawings which would detail things like electrical manholes , pipe ducts etc. this is so that you run pipes /conduits that would have to be in your foundation now, not as an afterthought that would involve breaking and recasting/patching.

do you have all your approvals [in my experience lasg regulatory bodies eye dey chook well well]

just my questions.

I think the site is on the ogun side of opic, nevertheless, we will do as you advice. Thanks sir

Marilo:
What is the total are of the land in square metre and what is the total built up area?

Total built up area is 12m x 20m (240sqm)
Site size is 29m x 18m. ( 522sqm)
Set backs of 3m by the sides, 2.5m at the back and 6.5m on the front.

Percentage built up area = 46%

EgunMogaji:
Thank you, Sir. We owe it to you guys that show us how it should be done and properly.

Will you be doing precast parapet on this build? I need to see latest information.

Good luck guys.

From some of my last experience, precast seems to be a bit expensive these days. We are going to do in-situ cast parapet /concrete fascia because the fascia is a going to flat with about 600mm projection as it is in the 3 D

Pictures of some of the iron work

EgunMogaji:
I was beside myself when I saw the topic actually. A new build - wow

Yes sir... And welldone on your building in ibadan, it is not really easy building in this present economic conditions

kopell:
Congratulation Abdul it's been a while we saw new stars up project. I thoughts most of the builders want on strike because of our public screwing.

Thank you sir, prices are so high that you don't want to take new job but we are very grateful to have a very understanding client. For this particular project, we move stage by stage because '' I no want enter wahala''
We review our expenses after every stage to cater for increase or decrease in materials.

diordaves:
So what determines the height of the raft? Is the height of the raft arbitrarily determined to the whimp and caprice of the builder or this is in relation and directly proportional to the level of the highest point of the surrounding area?

Would you normally need a land surveyor with theodolite (?) to take the level of the area to determine the height of the raft?

The hight of the raft from a structural point of view depends on load transfer from the raft slab and the shear stress from the column supported by the beams but from topography point of view since we build raft foundation in such a way that the raft slab also serve as the building ground floor level (popularly called dpc level) we tends to raise raft slab level above the natural ground level up to a level where the building will not be affected by flooding.

For this particular project a raft beam of 900mm was deemed structurally safe to carry the raft slab but due to the fact that the site is about 1m lower than the road level we had to raise the foundation height above the road level by about 700 to 800mm in other to cater for future increase in road level, which resulted in a total height of 1.8m.

Since the area is already built up we just took the highest point and set our build a little higher, you may need a dumpy level for this operation but in this case we use water level. Infact, our building dpc level is the highest in the street.

Iron reinforcement work: for the iron work we use the following materials

1. 16mm
2. 12mm
3. 10mm

Fir this particular project we use tiger brand of iron for his high tensile strength and overall quality. We make arrangements for an initial supply of 6tonnes of which we later bought 1/2 a tonne of 10mm to complete the job.

The top and bottom main bars were 3Y 16 ( in accordance to the structural design.

There were four nominal reinforcement at the center due to the height ( 4 Y12 both side)

And the ring spacing was put at 300mm c/c and we use 10mm bar for this operation

Materials for the formwork includes the following
1. 1 x 12 plank of about 600 pieces
2. 2 x 4 soft wood of about 200pieces
3. Binding wires of about 4 roles
4. 3'' Nail of 2 bags
5. 4'' nail of 1bag

Formwork : the raft beam is a 6 board raft (1.8m heigh),
For this particular project we budget about 500 planks initially

KolaShangOne:
Oga ABdul.. nice work.

Me and you don become neighbours. If you're still in Opic, we should see..

My oga thank you o.

I'm still around. Drop your address on whatapps so I can come see my oga

preparation of raft beam: raft beam ring height

Foundation blinding

Foundation work

1. excavation of foundation trenches : excavation work was carried out to have a uniform base point before applying a blinding of about 150mm to 200mm

For this project the depth dimension of the raft beam is 250 x 1800mm
while the depth of the slab is between 175mm to 200mm

FastShipping:
Did you come across snakes while working on this water-logged land? This is type of area where pythons hide.

We didn't come across any snake, the site is already built up

Stage three foundation work: The foundation type is near surface raft foundation
Raft foundation was employed based on the recommendation of the Geo technical soil report, prevailing site condition and foundation type of all the surrounding similar structures. An extensive investigation was carried out to know the foundation type of surrounding structure and it was observed that all the building in the estate were built on a near surface raft foundation.

I will start by defining what is a raft in a simple language: A raft foundation is a type of shallow foundation also known as mat foundation which is use when the bearing capacity is low in respect to the anticipated dead and the life load that the building is expected to carry, it covers the entire area of the foundation and help to distribute load uniformly thereby help to counter the effect of differential settlement in expansive clay.

We have the following type of raft foundation
1. flat slab raft
2. slab-beam raft

lab beam raft is further divided into
1. Up stand beam raft
2. Down stand beam raft
3. Cellular raft.

Analysis can be done rigid method or flexible method. The analysis is carried out using this simplified method.
1. estimation of floor loading intensity: floor loading intensity is the total load of the super structures coming to the foundation. In the case of a frame building it is equals to load coming through all the columns divided by the area of the foundation. for this particular project, the floor loading intensity was estimated to be 16kN/m2

2. Compare the loading intensity to the safe bearing capacity of the soil. safe bearing capacity= ultimate bearing capacity/ Factor of safety. If the loading intensity is lower than the safe bearing bearing capacity the raft foundation design can be carried out, otherwise the foundation area is increase

3. Estimation of the center of of area of foundation and center of gravity of load. If center of gravity of load doesn't correspond to that area, the corresponding eccentricity along x and y-axis are estimated.

4. application of the soil bearing pressure to the slab and designing of the slab like a suspended slab using coefficient in BS 8110 for two way slab or using manual analysis like a continuous beam for a one way slab. Note, unlike normal suspended slab load on raft foundation slab act upward not downward and the resorting bending moments are opposite to that of a suspended solid slab.

5. Design of slab like normal suspended slab

6. load from the slab are transferred to the beams and the beams are design like normal suspended beams.

7. checks are carried out for immediate settlement, secondary settlement and consolidation settlement using a soil profile (bore hole test is important here).

Some misconception about raft foundation.
1. So many people don't pay too much attentions to the raft slab by wrongly assuming that the beam is the foundation. The beam is a component of a raft slab but the slab is the main load distributor to the supporting soil, the beam help to reduce excessive shear stress along the critical perimeter of columns because of the magnitude of point load carried by the columns

2. the depth of the beam of a raft foundation is not governed by the safe bearing capacity but by the magnitude of load transfer from the slab it support and magnitude of shear force at column point

Stage 2: setting out
This involves transferring of information on the designs (structural and architectural design) onto the ground so that construction work can be carried out.

Here, we are going to be using profile board for our setting out.
Materials includes the following.
1.pegs
2. 2 x 2 as profile board.
3. nail.
4. Builder's rope.
5. Builder's square.
6. Claw hammer.
7. Meter rule
8 water level.

More

Stage one: Removal of all organic materials and soft soil strata up to a depth of 500mm

This involved the removal of all organic decay materials (vegetation) on the surface and all the soft clay up a considerable depth below where hard soil strata can be found.

The operation was carried out as follows
1. we mark out the external perimeter of the site with an allowance of 2m by all the four side.
2. We divided the work into 4 part and employed manual removal using ten labor
3. After removal we carted away loose soil to nearest by site
4. Finally, dewatering operation of the site was carried out

To the main building: here is what we have in mind

On the ground floor we have the following
Duplex side
1. Living room
2. Dining
3. Kitchen
4. Visitor's bedroom
5. Store
4. Visitor's toilet
5.General toilet

Two bedroom flat side
1. Living room
2. Dining area
3. Kitchen
4. two bedrooms with one en suit toilet and one open toilet

Fence block work

More fence bean work

More pictures

Fence beam brief description : before embarking on the fence beam construction we had to do some due diligence by going round the estate to investigate other similar fence built in addition to the result of our soil test report.

Here is what we have

topsy23:
Congrats boss

Thanks boss

Construction of perimeter fence :
Q perimeter fence measuring 30m, 30m and 18m is to be constructed around the site to finally isolate the ground water for easier site dewatering.

The grade beam/raft beam is 1.2m

The access road was filled, site demarcated and excess water pumped out in other to carry out the soil test by a geotechnical nominated by the client. At this point we were waiting for the result of the soil test to conclude the foundation design

The level of surface water was so high that we had to recommend immediate filling of the access road and the use of sand to demarcate the site perimeter so that we can pump out the excess water before a soil test can be carried out .This prompted our visit to the nearest sand fill to check a suitable and cost effective soil to use for the filling of the access. In this case, soil with considerable sharp sand locally called "yoyyo"

Site visitation: We visited the site December, 2016 to have a first hand information about the nature of the site before work can commence

Scope include the design and construction of this building. The design was carried out by Harney projects and the construction will also be done by Harney project. The client hired an independent firm to carry out the soil test based on the recommendation of our team on ground after site visitation

We will start off by thanking God almighty and Nairalanders ( Mr Qc1 for his referral and the client for his trust in our ability and integrity) for making this project possible. I thank you sirs.