Wednesday, 24 January 2018

How To Construct A Slab Culvert Over a Drainage - Engr. Osaz' Enobakhare

How To Construct A Slab Culvert Over a Drainage
Engr. Osaz' Enobakhare
Lagos, Nigeria.

Controlling flood is taking new dimensions. Canal-like ‘V’ drainages are taking root in many cities across the country. The advantage of utilizing less quantities of concrete and reinforcement than the regular drainage makes it cost less to construct and relatively flexible. This type of deigns allows the drain to be supported largely by the earth on its sides and bottom than its own weight. Most constructors of this type of drainage use BRC Wire Mesh as the reinforcement material in the concrete mass hence it is relatively light and not safe enough to support drain covers. Although this types of drainage using wire mesh, if not constructed properly are known to fail quickly under intense water pressure-forces. For this reason building a culvert ‘bridge’ over them to allow passage of vehicles become imperative so that the slab do not by any means bear on the drainage to avoid collapse. But the design of slab-culverts is quite different from the usual drain cover supported fully by the drainage because they would have to stand alone. To get it right, you should engage a structural engineer in designing the culvert which takes into account the expected load (or weight) the culvert will bear par functionality. Culverts designed to largely support heavy vehicles, trucks and trailers like those constructed to serve fuel/filling stations, warehouses, heavy duty parking lots and major streets are quite different from those constructed to support cars and light moving loads for small residential apartments hence the special consideration given to them.  Generally in constructing culverts, you have to;

1      Get a structural design. Set-out the area to construct it by its sides on both faces.


1     Excavate the foundation trench to the recommended depth, usually beyond the depth of the drainage.  Ensure that trench excavation is properly done so that the formwork can fit in properly. Let the trench be wide enough up to 500mm to allow for clearance (or extra space) between the earth and the formwork as well as the face of the drainage and the formwork.

     Install the formwork using timber (wood) or steel with adequate bracing. The formwork should neither lean wholly on the drainage nor the earth so that it can be removed once the concrete sets. Build the slab formwork together at once. Brace the soffit (bottom) of the slab properly so it doesn’t collapse during construction.
    Look up the structural design and fix reinforcement accordingly. Usually the foundation is constructed as a solid raft (with main reinforcement and distribution reinforcement spanning from bottom of the trench to the top in all directions) and the slab is constructed like a beam (with top and bottom reinforcement, up and down bound by stirrups) and fixed together, not like typical floor slab ‘mat’ in buildings.
    
   Prepare and place concrete of good mix into the formwork (depending on the strength requirement a mix of 1:1.5:2 is normally recommended). With the aid of a poker vibrator, vibrate the concrete in the formwork properly to avoid pores and void. Then leave to set properly before detaching the formwork. Then you are good to go



Tuesday, 23 January 2018

Latest Cost Estimates of Building Projects in Nigeria 2018 (Osaz'Index)

Based on popular request, your first choice contractor and construction partner, Engr. Osaz' finally brings you the latest building design and construction cost index valid for towns and cities across Nigeria, sourced from priced bills of quantities/quotes of quite a number of completed and on-going private projects, and based on wide consultations with relevant industry stakeholders especially Contractors, Quantity Surveyors, Builders, Engineers and Architects.

It is important to note that no two projects are exactly the same in scope and extent of work to be done and we hope you also know that we do not reserve the right to determine what fees or bill any contractor or professional handling any project should charge a Client or Project Owner at any time, hence the figures displayed here only serve to guide you so as to make informed decisions. 

This therefore doesn't give any contractor or project handler any particular advantage over the other as sources of estimates for this research remain confidential.  





The cost parameters has been divided into three main categories - Design, Structures & Services and Finishes.

Design - Architectural Drawings, Structural Design, Electrical Services, Mechanical Services Designs and other relevant working drawings.

Structures & Services - Foundation/Substructure works, Columns, beams, stanchions, floors, staircases, Lintel, arch, block/brick wall, steel panel wall systems (where applicable), roof carcass, roof covering, windows, doors, ironmongery, Plumbing and Electrical Installations etc. 

(The rough estimates for Structures & Services is based on the assumption that the parent wall material is made of reinforced concrete, block, brick or steel or a combination of any of them. It is also assumed that a soil test must have being carried out to determine the depth of suitable subsoil for foundation. Plumbing and Electrical installations doesn't include expensive gadgets like AC, Jacuzzi and Bath Cubicles.      



Finishes -Wall Finishes, Floor Finishes, Ceiling Finishes, Fitting, Fixtures and related items of work.

Generally, costs of finishes are largely subjective and differ with individual tastes and preferences, therefore for the purpose of this Index the cost of finishes only represent the cost of regular finishes (i.e. cement-sand rendering, plastering, normal painting, fair quality wall and floor tiles, PVC ceiling or its equivalent etc).  


The rough estimates for External works (e.gPerimeter fencing, soak-away pit/septic tank. borehole, Interlocks or pavers, beautification, external security furniture, landscaping, etc) are not included anywhere in the list. 


Because of the level of discrepancies observed in construction bills from location to location, handlers to handlers and with differences in designs and site conditions, it was only reasonable to present Osaz'Index in a range value format as seen below.

If you need clarification about any item listed here, askEngineerOsaz'


Rough Estimate of 1-Bedroom Apartment (Detached Bungalow)
Spaces: 1 Bedroom, 1 Living room, 1 Toilet/Bath, 1 Terrace, 1 kitchen
Max Building Area: 50sqM
Max Height: 4m
Soil Condition: Dry Land, Suitable subsoil within 5-metres depth



Rough Estimate of 1-Bedroom Apartment (Detached Bungalow)
Spaces: 1 Bedroom, 1 Living room, 1 Toilet/Bath, 1 Terrace, 1 kitchen
Max Building Area: 50sqM
Max Height: 4m (Detached Bungalow)
Soil Condition: Water-Logged Land, Suitable subsoil within 5-metres depth

Rough Estimate of 1-Bedroom Apartment (Semi-Detached Twin Bungalow)
Spaces: 1 Bedroom, 1 Living room, 1 Toilet/Bath, 1 Terrace, 1 kitchen (Per Unit)
Max Building Area: 120sqM
Max Height: 4m (Detached Bungalow)
Soil Condition: Dry Land, Suitable subsoil within 5-metres depth




Rough Estimate of 1-Bedroom Apartment (Semi-Detached Twin Bungalow)
Spaces: 1 Bedroom, 1 Living room, 1 Toilet/Bath, 1 Terrace, 1 kitchen (Per Unit)
Max Building Area: 120sqM
Max Height: 4m (Detached Bungalow)
Soil Condition: Water-logged Land, Suitable subsoil within 5-metres depth
        

Rough Estimate of 2-Bedroom Apartment (Detached Bungalow)
Spaces: 2 Bedrooms, 1 Living room, 1 Ante-room,2 Toilet/Bath, 1 Visitor's Toilet, 1 Terrace, 1 kitchen
Max Building Area: 180sqM
Max Height: 4m (Detached Bungalow)
Soil Condition: Dry Land, Suitable subsoil within 5-metres depth


        


Rough Estimate of 2-Bedroom Apartment (Detached Bungalow)

Spaces: 2 Bedrooms, 1 Living room, 1 Ante-room, 2 Toilet/Bath, 1 Visitor's Toilet, 1 Terrace, 1 kitchen
Max Building Area: 180sqM
Max Height: 4m (Bungalow)
Soil Condition: Water-Logged Land, Suitable subsoil within 5-metres depth

   


Rough Estimate of 2-Bedroom Apartment (Semi-Detached Twin Bungalow)

Spaces: 2 Bedrooms, 2 Living rooms, 2 Ante-rooms,2 Toilet/Baths, 2 Visitor's Toilets,2 Terraces, 2 kitchens (Per unit)
Max Building Area: 250sqM
Max Height: 4m (Detached Bungalow)
Soil Condition: Dry Land, Suitable subsoil within 5-metres depth




Rough Estimate of 2-Bedroom Apartment (Semi-Detached Twin Bungalow)


Spaces: 2 Bedrooms, 2 Living rooms, 2 Ante-rooms,2 Toilet/Baths, 2 Visitor's Toilets,2 Terraces, 2 kitchens (Per unit)
Max Building Area: 250sqM
Max Height: 4m (Bungalow)
Soil Condition: Water-Logged Land, Suitable subsoil within 5-metres depth



Rough Estimate of 3-bedroom Apartment (Detached Bungalow)
Spaces: 3 Bedrooms, 1 Living room, 1 Ante-room, 3 Toilet/Bath, 1 Visitor's Toilet, 1 Terrace, 1 kitchen
Max Building Area: 150sqM
Max Height: 4m
Soil Condition: Dry Land, Suitable subsoil within 5-metres depth
        




>>>>>>>Don't keep this information to yourself. Always mention to your friends that these prices, costs or values are Osaz'Index or that you got this tip exclusively from  EngineerOsaz's blog. Thank you and Success on your project!<<<<<<<<

Rough Estimate of 3-bedroom Apartment 
Spaces: 3 Bedrooms, 1 Living room, 1 Ante-room, 3 Toilet/Bath, 1 Visitor's Toilet, 1 Terrace, 1 kitchen
Max Building Area: 150sqM
Max Height: 4m (Bungalow)
Soil Condition: Water-Logged Land, Suitable subsoil within 5-metres depth

         











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Current Construction Workers' Labour Rates in Nigeria 2018 (Osaz'Index)


Engr. Osaz', your contractor of first choice keeps you up-to-date with the current labour rates for the construction industry across Nigeria. 

These rates are based largely on independent (in-house) research from on-the-field observations together with figures from wide consultations with other construction professionals across Nigeria. 


We hope you know that it is not within our powers to determine what any worker earns or how companies pay their construction workers. Therefore these rates only serve as a guide. We are determined to update it from time to time. 

However if you find any rate that is a foul cry from what obtains in your area, kindly indicate in the comment box. We will verify and update quickly. 

Reliably Yours! 


HSL - Highly-Skilled Labour, SL - Skilled Labour,
SSL - Semi-Skilled Labour, USL - Unskilled Labour

Generally, 1 day = 8 hours of work and 2 hours of break



















Don't keep this information to yourself. Always mention to your friends that these prices, costs or values are Osaz'Index or that you got this tip exclusively from  EngineerOsaz's blog. Thank you and Success on your project!








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