What are the prices of Granito tiles?

I have been reading through this thread and I commend everyone for the useful information shared. It's priceless.

I am in the unenviable position of trying to undertake a construction project while living outside the country. I know it presents huge risks but I still wanted to get the project started as I plan to get back and manage the project.

Since pictures replace 1000 words, above is a picture of the foundation of standard residential apartments I am putting up; nothing fancy. The area of the land is approx. 230 sq m. The plan s to build 3 two bed-roomed apartments and 1 one bed-roomed apartment per floor. The ground floor will have shops + res. units.

The footers have been built and 4 layers of stone and about 30 foundation columns have been erected. Contractor plans to back-fill the interior space with the soily material your see on the right side as hardcore.

Up to this point, I felt my contractor was doing OK, until I saw what he plans to use for "Hardcore". My question is, is this material proper to use in place of real hardcore which should be larger gravel stones? In my budget, I have hardcore, ballast and sand catered for. Why would my contractor use this material instead of the budgeted items? This has raised doubts in me and I have stopped the construction at this point. Also what would (have) been the correct rod (chuma) size to use on raising the foundation columns; y12 or y16? He says he used Y12 in some sections and Y8 in others. Is Y8 used in any part of the foundation?

I am planning to send a structural engineer to evaluate the work done so far and if necessary recommend amendments. Is this a feasible arrangement. If so can I get some leads?

Thanks @Mosby. I would be relieved if the murram in the picture can be used for back-filling and the hardcore placed above it. I will verify again where any Y8's may have been used, and if any have been used in raising the columns. Do you also mean that without the structural engineer's drawing I cannot get an evaluation of the structural integrity of the foundation?

I thought it was mandatory that all buildings have a Structural Engineer's drawing which gives details regarding the chumas, foundation, slabs, columns, load bearing, balconies, staircases, roof etc etc, before they are approved. The structural drawing also guides fundis on the quality, quantity, sizes etc of the various materials to be used at each stage.

I have independently verified that NO Y8's have been used in erecting the columns, they are Y12's. My contractor has also indicated that he is using the services of a structural engineer, so what I want to do is hire my own to confirm that I am getting the proper service.

Since I have paused the construction, I have time to travel and gauge everything before I decide to proceed or not.

Really! even if it's a residential highrise building with 4 storeys? Can the columnless load-bearing walls support the dead load?

Can I assume that this is something that would/should have to be incorporated in the architectural and structural designs stages though?

@apricot. Construction projects the whole world over follow the simple rules below.
1. client and architect
2. client, architect, qs
3.client, architect, qs, engineer
4.client, architect, qs, engineer, contractor.
5.client, architect, valuer,end use
Any other method of implementing a construction project, no mater how big or small, will most likely lead to failure in terms of viability or structural integrity.
What i can deduce is that you are not using this procedure.
Your architect is mandated by law to first explain to you how construction industry work. This is step A in the CAP 525 of the Laws of Kenya. See here http://a4architect.com/about-us/fees-breakdown/

Its your responsibility as a client to find and consult a registered architect who is trained and has the necessary experience and certification to offer this service to you.
After this, you will not have the kind of problems/questions that you have expressed below.
Once you have retained an architect, he will advice you the roles of engineers, contracotrs etc.
The world over, it is the responsibility of the owner to retain a structural engineer. Its not the responsibility of the contractor to do so.If the building collapses, its the owner, not the contractor who will be held responsible for structural defects.
Also, in selecting contractors, select registered contractors who can also advise you on the norm in the construction industry when you are wrong e.g. when you have no engineer as opposed to a contracotr who takes advantage of the situation and gives you wrong advice.
Previously, Kenyan laws could not enforce developers to use laid down procedures. Currently, the kind of fines you are facing are kind of huge, basing from the new construction laws. The law is drafted such that its impossible to feign ignorance.
Google for Built Environment Bill 2012. It has specified huge fines for developers who don't follow rules. Last time i checked, the fines were in between hundreds of thousands to millions.

My appeal for developers is for them to ensure they follow rules so as we dont make Kenya another Haiti with alot of unplanned and un supervised collapsing buildings.

The reason construction cost in Kenya is higher than in South Africa is coz Kenyan developers avoid/are ignorant on the use of consultants to enable cost savings .Kenyan developers mostly use fundis/contractors for the wrong skill/set hence dont benefit from use of cost cutting techniques/ideas which come about from consultants.

Why would a QS come before an Engineer? just asking!

Also Apricot:

Did you obtain the necessary permissions to build from the county/council authorities? if you had, they would have asked for the structural drawings, then you would have known to consult with an structural engineer to generate those drawings.