Tying Reinforcement Steel in Raft Foundation with cable ties. Any Thoughts

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mister mac

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I am just about to start a Raft foundation on my self-build. Anyone who has seen a raft under construction before will know that it contains alot of steel.
I asked my Engineer about tying the steel with strong cable ties instead of tying wire (to speed up the construction of the steel form) and he said he could see no problem with it. I have also mentioned it to a few other people who would have experience in groundwork’s/construction and they say they cant see any reason why not.

My thinking is the tying wire is only for holding the steel in place until the concrete goes off. Once the concrete has set then the tying wire serves no purpose as the concrete holds everything in place.

The only thing I can think of is that the cement in the concrete might over time burn away the plastic cable ties , but does this matter as the foundation will be set solid.

Any thoughts much appreciated
 
wouldn't have thought there'd be any issue at all. As you say, the ties are only to keep the reinforcements in the correct place until the concrete sets.

You could try metal cable ties if you're worried about the plastic degrading.
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mister mac,

I assume you are planning to fix the reinforcement yourself.I cant see why tying the reinforcement with cable ties would be any faster.Also would the cable ties hold the reinforcement in position as the slab is being pokered (vibrated).Steel tying wire is tried and tested and if there was a faster way of doing it would have become the norm in the last 10 years of craziness.
 
wexford dude said:
I assume you are planning to fix the reinforcement yourself.I cant see why tying the reinforcement with cable ties would be any faster.Also would the cable ties hold the reinforcement in position as the slab is being pokered (vibrated).Steel tying wire is tried and tested and if there was a faster way of doing it would have become the norm in the last 10 years of craziness.
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Agreed. I really can't see cable ties being any quicker and i doubt you'll get as strong a 'bite' as with tie wire. Are you planning on tying the rebar yourself? If so after the first thousand or two ties you'll soon get the hang of it.
 

Have seen a lot of rebar tied in my time, and also when insufficient ties where used the incoming concrete can easily move the bars , which can of course impact on the design and stability of the slab.

The tieing of the rebar , as a poor work posture is another days work, but be prepared for extensive lower back problems!
 
GarBow said:
Agreed. I really can't see cable ties being any quicker and i doubt you'll get as strong a 'bite' as with tie wire. Are you planning on tying the rebar yourself? If so after the first thousand or two ties you'll soon get the hang of it.
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I agree, with tying wire you will get a much better tie that will stop the rebar moving and possibly separating during the pour.
 
Am planning on tying the steel myself. My main reason for considering the cableties is that it would be quicker to loop round a cable tie and pull it shut compared with wrapping round a bit of tying wire cutting, clamping it in the nips/cutter twisting and cutting off excess.(imho)

In the raft drawing there is enough steel to hold up a skyscraper never mind the dormer that wer building so I would imagine that if a cable tie is used at every steel overlap and juncture of the frame it surely could not move.

I was planning on using 8mm wide cable ties which are quite hard to break.

I take your point wexford dude that this probably would have been thought of before but maybe its something an engineer would not sign off on because they had never seen it done before.
The jury is still out on this one I think, Thanks for all the opinions
 
mister mac said:
Am planning on tying the steel myself. My main reason for considering the cableties is that it would be quicker to loop round a cable tie and pull it shut compared with wrapping round a bit of tying wire cutting, clamping it in the nips/cutter twisting and cutting off excess.(imho)

In the raft drawing there is enough steel to hold up a skyscraper never mind the dormer that wer building so I would imagine that if a cable tie is used at every steel overlap and juncture of the frame it surely could not move.
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There could be enough steel to hold up ten skyscrapers but if it's not placed and tied properly then it may as well not be there. If tied properly with tying wire, a tie at every second or third juncture would suffice, which would take considerably less time than tying a cable tie at every juncture. Believe me, you will become quite fast at it in a short space of time.

It's your house, don't cut corners, especially not at foundation stage.
 
Also why so much steel? Is your engineer a bit anxious of failure. A393 mesh top and bottom with chair spacers with U Bars at the edges should be fine for a standard house raft. It would save you an awfull lot of tying too. Just as a note, when an engineer signs off steel reinforcement before a pour, they do take into account the ties also so i can't understand your engineer suggesting plastic cable ties could be a runner.
 
There is a specific tool for twisting the wire ties (which should be purpose made with a ring at each end). The tool has a hook which engages the rings and is then pulled to twist the wire ties. Fast and much simpler that twisting and cutting wires to length.

Can't remember what the tool is called as it is over 40 years since I saw one, but I'm sure they must still be about.
 
BillK said:
There is a specific tool for twisting the wire ties (which should be purpose made with a ring at each end). The tool has a hook which engages the rings and is then pulled to twist the wire ties. Fast and much simpler that twisting and cutting wires to length.

Can't remember what the tool is called as it is over 40 years since I saw one, but I'm sure they must still be about.
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+1 .... I concur .... great tool.

Ask a builder for a loan .....
 
selfbuild09 said:
Have a look t this. http://www.ecplaza.net/product/137011/788229.html. I just whipped this from google, it's from china I think.

I saw one of these at the ploughing in Kilkenny last year. Expensive at about €1500 - 2000 but if you tie stell all day every day it will save some heartache.
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I had one a few years ago, they are a disasterous gimmick. I have tied a lot of rebar in my time, as have many steelfixers and more often than not the ties are inspected by engineers. Steel fixing is paid by the ton. Therefore, the more steel you tie in a day with PROPER ties that will pass an engineers inspection, the more you earn. I and the other steelfixers always did, still do and probably always will use tying wire tied with a good old-fashioned nips. Best practice anyone??
 
My guess is that if an engineer won't pass loose wire ties he won't pass plastic cable ties. Good point though as the one thing I did notice is that machine didn't tie the ties as tight as you could with nips.
 
selfbuild09 said:
if you tie stell all day every day it will save some heartache.
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Aswell as not giving a proper tie, you certainly won't be tying steel all day as you will spend a good portion of your time unclogging it, charging it, hitting it with a hammer in frustration......
 
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