₦airaland Forum

tiper of sand...3.5m

Raft with a combination of ground beams will serve the purpose.

1. It better to get a competent engineer to work this out
2. Do a soil test
3. If its just a bungalow or storey building, raft foundation is ok and less expensive dan piling

But please consult a good engineer to avoid building defects and colapse

All those claiming HND distinction, B.Eng...and PHD Civil Engineering will not make concrete contribution snow .. Still yet they are looking for lucrative jobs with forged CV. This is applied Engineering. Oya say something. Recruiters please come in and know who is good in practical and who only read books without application. Am following this thread back to back. Seasoned Engineers over to you. I am a Mechanical Engineer there is little I can contribute.

Do a soil test... I can connect you with a builder because I'm not in Lagos. And next time, before you acquire a land, get an expert's opinion.

Contact professionals for every details, designs, servicing and structural help. 07057666658

You can contact Concrete Logistics Limited for your concrete waterproofing -casting, joint and wall plastering waterproof. Call 08052219602.

Pile is most advisable but i'll recommend you do a soil test... that will show you the exact bearing capacity of the soil.

Pile fdn is quite costly...raft is vry ok ad ensure to introduce dam proof course during constr for future purpose.

Hello poster,

The best foundation to adopt is pile foundation. Raft is not adviseable because even if there is even settlement of the foundation that means you will loose the ground floor because the house will sink. I am into pile foundation and I understand your fears. If you don't mind you can contact me on 09029145004. Then I can explain better to you or you chat me up whatsapp so I can exchange pictures with you. Whatsapp Nos. 07060602143

that foundation sure gonna gulp so much

talk2riel:
Raft with a combination of ground beams will serve the purpose.

Seconded

Do you need a soil text again in swampy area?no is the answer.Just get a sound structural engineer to design the number of iron rod and the type to use for you and to save cost,you can go for Raft..for granite and sharp sand,u can get in touch with me

I hope u will get the info u need

bigi4u:
Pls my dear engeneers in the house, i salute you all.

I have read some of your advices on building on waterlogged areas and i appreciate your comments, but mine is a little different and i'll need your candid advises.

Please i bought a plot of land of 60 * 120 in iyana iba area, Lagos. its a waterlogged land (for sake of cost). with a layman experience i used a long narrow stick to see if i can determine how deep to the (Bedrock) solid ground beneath, it took between about 3ft (close to shore dept) to 6ft (centre dept) to pass the softtop(debris, decaying grasses, no mud, the soil is sandy, looks like sharpsand) to get to strong ground. i've filled it to some extent with filling sand, meanwhile some building are being erected in there but some didn't get their foundation well done, which is part of what i'm trying to avoid.
Now, i'm ready to build, (atleast the FOUNDATION for now), pls like how much will it cost to lay a good durable but cost effective foundation of 2 storey building of single 4 bedroom flat, (1 flat at ground flour, 1 flat at 1st flour) (BQ sort of.) and which type of foundation will be best option, considering its various depts and the costs (cos I don't have much, just trying to escape from high lagos rents and planning for retirement.). What will it require?

Also can the foundations be done in bits, (ie, casting now and german floor much later if raft or also in piles) or must everything be done at once? Please your help is highly needed for me to know what next to do.
Many thanks from bigi.

My candid professional advice is PILE FOUNDATION.

Structural stability is first to be considered when it comes to building.
Pile foundation is best for this scenario.
Only when both has satisfied the stability criteria, then cost effectiveness can be considered.

Be warned!!!
Make sure you construct through the DUE process.

Thanks

opalu:
@Topic
Every Site has its own peculiarities. And as a Structural Engineer, I would need to examine yours before diagnose what type of foundation is best suited. Just as doctors can't use a single symptom to judge the type of drug, likewise it's wrong for any Professional in this field to use the word Swampy to judge the foundation type.
Therefore you will need a competent Structural Specialist to check it out and give you expert opinion. He may likely advise a soil test if he deems necessary.

@ALL

I usually advise my clients especially those about to purchase land for building project to go with an expert. You don't just carry a lawyer to look at the land and look at the neighbouring houses and the title documents and conclude it is a good deal. All those are proper but you need an Expert eye that can see many things you can't see.

Due to the recurrent issues of foundation that I receive year in year out, I categorised lands for building into 4 groups. I can only explain 2 and you will understand the rest
1.

I Second this. Not only are the soil of different areas unique, the factors that affect them ( e.g. rain, water table or broken water mains for a water logged area) can also make profferred solutions unique to the area. Also the type of building you want to have now and in future on it will be taken into consideration.

Giving you solutions online for it will trial by error.

Get a civil or structural ENGR. If you don't have one now, make one your friend or hire. Take him to the site for assessment. If he needs to get a soil test for it he'll tell you ( some can actually assess and tell what kind of foundation that would be applicable without a test based on intelligence and experience). But avoiding both the ENGR and the soil test is inadvisable for your site.

People need to start having engrs as friends. Even if he's a Mechanical or Electrical ENGR ( who actually studied these courses) he'll know the right person to contact for you cos many work together and have links among themselves.

If u r planning to build a single or multi-storey building, you should employ the service of a professional to conduct an accurate soil test. Then afterwards consult a Structural Engineer (not just any engineer, pls take note) to prepare accurate and approvable Structural designs. You can't rely on your architectural drawings alone.

But generally for bungalows, you can use a suitable raft with the ground floor elevated well above water table and properly built. The raft must be constructed at a depth of suitable sub-soil. You may use short bored piles depending on which is considered cheaper or even a combination of both.

It may be wrong to assume that Pile foundations are more expensive than Rafts. Several cases have proven otherwise.


From a professional point of view, It is the discretion of the Structural Engineer to choose which foundation type is the most suitable based on technical grounds alongside cost effectiveness. We are trained to do so and very recently we issue legal warranties of up to 50 years of structural strength and stability, within which we would be held responsible for defects or failures arising from poor designs/works.

It's penny wise pounds foolish not to consult the right professional for your project.

Engr. Osaz
±2348167394799

Strip, with ground beam will do fine

Isn't the the 2nd time that this question is asked?

Brother look for geotechnical engineers to carry out soil analysis to enable you know the suitable type of foundation to use

Look for a competent Registered Civil Engineer to do the design and recommend foundation type for not on Nairaland.

Contact a registered civil/structural engineer[b][/b].
However, from experience, you will be needing a raft of between 1.2m -1.5m depth. I don't think a pile foundation will be necessary for just two storey building in any part of lagos. Except you are building on water.
But like I said earlier, look for a good registered engineer. The cost of employing the service of an engineer will be nothing compared to the loss if your building should collapse.
Regards.

what a hell, who told you that

please do a soil test before anything. i strongly advise.

udmbat:
Raft is preferable because of cost. Pile is too expensive.

I will suggest you carry out geotechnical investigation @ d site.

Both raft and pile are two good options but as for me, i would imploy you to go for raft, its owk if you can endure the cost... Pile foundations are mostly used for bigger project.. I can give 99.99% trust on it... Make sure its a german floor with dpc (damp proof course) BEST OF LUCK

[b]Op; I'll respond to your question as a construction cost professional.
Many engineers here have given you very good advice about getting a a professional engineer to assess your site & proffer the best solution for your problem.
However, from your description of your site, my professional experience & from a cost perspective, I must say that any solution that the engineers would proffer will be costly for you when compared to you buying a dry land. Like someone said above, why buy a waterlogged land & spend so much to make it good when you can get a better dry land & spend less on the foundation?
I would have advised you to sell off that land, cut your losses & go and buy a dry land at a cheap price elsewhere, there are so many adverts on that on Nairaland.
But if you still wish to go ahead with this land, then go with the engineer's professional advice, though it will cost you a lot in filling & foundation works.
My Candid Advice as a Quantity Surveyor!
Funny enough, I am about to start a new topic on my thread by tonight or tomorrow tagged "BEWARE! THESE LANDS CAN INCREASE YOUR CONSTRUCTION COSTS ASTRONOMICALLY! What a coincidence!
If interested, You can follow my thread "TALK TO QUANTITY SURVEYORS ABOUT CONSTRUCTION COSTS & PROJECT MANAGEMENT" from tonight or tomorrow. You can ask make cost-related enquiries there.[/b]

https://www.nairaland.com/2836058/talk-quantity-surveyors-construction-costs

Considering the two factors you have mentioned which are the nature of the soil and the size of the proposed building. Raft foundation with depth between 1.2meters -1.5meters would be suitable for you. You can reach me on 08085034654 for further help.

To start with, Kudos to the construction related experts that have contributed.

Moreover, there is something some of us are missing. In a scenario like this, you can just advice for either Raft or Pile.

Both are use for ground with low soil cohesion resulting to a low or very low bearing capacity.

Best thing is to go for SOIL TEST and SITE INVESTIGATION.

But note, DCPT might not work here except SPT or BORE-HOLE test which requires laboratory analysis.

This test might cost you between 180,000 to 250,000 but you are rest assure of the safety of your structure.


I am a construction professional, kindly PM if you need professional advice.

www.abkadconstruction.com

clients@abkadconstruction.com
acwl4u@gmail.com

Regards.

The soil conditions described are too vague toarrive at a precise recommendation but if the choice is strictly between rafts and piles I would score it 3:1 in favour of 'short bored piles'.

Goal No 1 for piles: Rafts act the way boats do on water. Vertical stability is achieved by a balance between the surface exposed to the soil and the mass being displaced. The problem arises like a boat when the centre of gravity moves, is in-equidistant or far from the point of contact (as in a tall building). Rafts donot offer much horizontal or rotational resistance. You are building 2 storeys, most residential buildings are notorious for eccentric loads. Piles offer better all round resistance in everything but a bungalow.

Goal No. 2 for piles: Volume of materials and works required for rafts: concrete, rebar, shuttering/shoring, dewatering is far in excess of those required for piles for the same loads and soil condition simply because the efficiency of the raft is proportional to its 'spread' (size). Not absolutely true for piles.

Goal No. 3 for piles: Due to financial limitations you wish to place your foundations in stages. Well, without expensive dewatering regimes you may not be able to do it with a raft, You will have structural and water proofing issues as well since the integrity of a raft requires monolithic assembly. Piles on the other hand can be instaled piecemeal.

Goal No. 1 for rafts: In practice, piles are much more technical. They require proper and detailed soil analysis and engineering design. Their construction requires machinery and tolerances are small. In other words it is either done properly or avoided. When they fail the results are catastrophic. They are less forgiving than rafts.

Guyman02:
It is then advisable to leave the newly laid foundation for some time of about three to six months for an area that is seasonally water logged and six to 12 months for an area that is averagely water logged before the final work plan of building is set up. This is because the compressed stones and the disintegrated soil must be given room to fully attach itself together to attain a firm and strong foundation.

Consolidation right?

udmbat:
Raft is preferable because of cost. Pile is too expensive.

Not true. For everything but the lightest loads and the safest soils, piles are cheaper.