Foundations

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bskinti

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How do I convince a client to put in caged re-bar in a foundation, He insists that I put in mest reinforcing as a large builder done on his friends house because it was cheaper and articect accepted this and both have same articect, To me its making a mess of what is the most important part of the house, I always have put in fully caged bars before pouring cement.Where would I get some info to try and change articect and cliants mind, I plan to pour at easter
 
If he can not accept the obvious facts put before him at the most crucial stage of his build, me thinks you have a client that you are going to have a lot of confrontation with over the coming months, how about contacting Homebond
 
you dont say type of found - why do you feel you need tied steel cage for the foundation? is it really required. Tied cages are more expensive obviously due to labour and amount of reinforcement but they are not usually reqd in most circumstances
 
I put both in my foundation quite cheap in relation to what build costs
 
what i meant was in relation to mesh, tied bars are more expensive -

A252 MESH - 8mm bars at 200 c/c, say€7/sq m
versus 8mm straight bar tied, say 0.90c/m and will need 10m to do same area = €9/sq m

factor that up for a 200sqm slab = extra 400euro

....if you could save nearly 30% on each item in your build....buy yourself a nice new car (or pay for a project manager and let him do the work :)
M

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Very unlikely you would need a cage in a small house found.
Conc is hugely strong under compression, from loads of walls etc.
The mesh is just there to prevent cracking in surface mainly, but also on bottom.

Will you perhaps get paid more if you put together the cage and supply the steel and even bend the bars your self?!;)
 
I would say a cage is unnecessary, unless there are particularly high loads / moments on the foundation. In a domestic situation, two or three T12 bars at the base of the foundations should suffice for catering for tension loads
 
Bit late with the thanks to everyone, Have learned a lot, Talked with another architect and he told me that mesh was sufficient on most house projects, and that was what most builders use nowadays, Waiting on brickie to start footings,
 
There is specialist's literature on the issue:"Concrete Construction Manual" by Friedbert Kind-Barkausus, Bruno Kauhsen, Stefan Polonyi, Joerg Brandt( the cream of concrete engineers). Publisher is Birkhaeuser, ISBN 3-7643-6724-5
On the EU continent ANY foundation slab/strip MUST be caged. It makes no sense to put in a steel reeinforcement mesh without caging to protect against tensile forces when the shearing forces aren't considered. Sack these architects and get a real civil engineer in. Any dud can call him/herself an architect in Ireland, so be careful.
Imagine the home owner decides to put more load on the slab/strip then it was originally projected. An extension, a car park,a water storage tank for solar heating or some digging work next to the foundation, or some overseen water/sewer leakage next to the foundation or whatever....disaster is programmed without caging. Saving a few bobs (€500?) but risking the collaps of an entire structure-why? Who would get these €500 - the homeowner or the cowboy?!
 
There are reasons I like re-bar tied in Cages. I have seen foundations been put in and a few bars threw in after and it dont take much time to cage and set thies in first, as I work normally on industrial sites all foundations are done in this way, I have put in a number of foundations for houses and always cage, Less work on day of pour, but with changing times one must move on, although I dont approve I will accept what I'm being told.
 
First of all, Architects cannot and should not specify reinforcement in foundations. Leave that to us! :)

Secondly, housing jobs do not normally require tied rebar. Mesh is usually satisfactory. I'm not sure what heinbloed means about it making no sense to put in mesh without caging. Steel mesh fabric is a stand-alone rebar. It is used in foundation to allow the strip footing or concrete slab to span over any local soft spots in the soil and also to prevent cracking. Rebar cages are used when the span lengths are very large, e.g. in a ground beam spanning between two piles.

Get an structural engineer to specify structural issues and leave architecture to architects!
 
What I meant is that the "spanning over" must be calculated and not guesstimated, for example by an engineer. What can not be calculated is the load that might occure when a change to the calculated forces is happening, as I said above. A signed calculation sheet would be most helpfull to determine the cure for any unforeseen changes in load or underground situation.
Similar to meassuring the blood pressure/fever before deciding how to cure/prevent an illnes.
Saying there SHOULD be a mesh-or two of them- in this and that position-(spacing?overlapping?coverage?) won't do.
Europes only new build nuclear reactor in Finland SHOULD have a certain strenght in the foundation, alas, they thought a mesh would do.....(smiley).
 
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