# Forum Home Renovation Structural Renovation  Joining two "C channel galvanised steel together

## mullfitz

Hi all I am considering using the below for some temporary decking scaffolding as bearers as I   have a few  left over  from another job  Anybody have any idea of how I could join the two together without welding as I have no power on site   
Thanks

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## ringtail

The application aside, bolts are your only option

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## mullfitz

Thanks mate would you think putting  treated pine or flat steel  between the C channel  and then bolt onto that a  good idea

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## ringtail

I don't see a need to put anything between the steel. Don't use building bolts either. High tensile is what you need. Not saying this makes them fit for your intended purpose though.

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## SilentButDeadly

Local steeline franchise sells some nice flange bolts and nuts for purlin brackets which should work fine for bolting them back to back. 
Can't say they'll work for scaffolding though....

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## mullfitz

> Local steeline franchise sells some nice flange bolts and nuts for purlin brackets which should work fine for bolting them back to back. 
> Can't say they'll work for scaffolding though....

  
So something like this should do the job

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## cyclic

> Hi all I am considering using the below for some temporary decking scaffolding as bearers as I   have a few  left over  from another job  Anybody have any idea of how I could join the two together without welding as I have no power on site   
> Thanks

  Doesn't no power equate to no drilling of large holes , so battery drill and self drilling hex head roof teks, 25x12, 2 every 450.
I assume you are joining the c section back to back.
Why does that not look like c section, or is it very small.
I am thinking 100x50 c section for scaffold beam.

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## mullfitz

> Doesn't no power equate to no drilling of large holes , so battery drill and self drilling hex head roof teks, 25x12, 2 every 450.
> I assume you are joining the c section back to back.
> Why does that not look like c section, or is it very small.
> I am thinking 100x50 c section for scaffold beam.

  Thanks for that  
Here lies the problem its only some temp  scaffold and wont be there long  I already have about 20 of these so would like to use them but   the main reason  I am not using 100 x 50 is  the  price for the 100 x 50 would be around $300 and due to the location of where the block is they are asking $125 for delivery   
I also have a cordless drill DEWALT with two 4.) amp batteries on site  
I hope that makes sense

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## SilentButDeadly

> So something like this should do the job

  Yep

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## toooldforthis

> Doesn't no power equate to no drilling of large holes , so battery drill and self drilling hex head roof teks, 25x12, 2 every 450.
> I assume you are joining the c section back to back.
> Why does that not look like c section, or is it very small.
> I am thinking 100x50 c section for scaffold beam.

  
look like Z purlins?
not C sections?

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## phild01

> look like Z purlins?
> not C sections?

   I can't make head or tail of what they are :Confused:

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## r3nov8or

I'm not sure if you want to make a longer one or a stronger one.

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## havabeer

If youre going back to back: 
squirt a coulpe of tubes of liquid nails between them
use a heap of m8 bolts to join them together, ten screws may do the job but bolts are safer 
if if you're trying to join them end for end:
use the same above method but just use 3 and use one as the overlap over the join

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## Whitey66

If you want to make an RHS type section out of them like this [] , just place them together and tech screw along the overlapped edges.
I don't know what you other guys are smoking but they look like C sections to me  :Smilie:  .

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## phild01

> I don't know what you other guys are smoking but they look like C sections to me  .

  Ah, can see it now.  One of things that can look like two different things.

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## mullfitz

> I'm not sure if you want to make a longer one or a stronger one.

  Loving the great advice and the  fun banter  :Smilie:  
Going to join them back to back anyone have any advice of  the depth I  should come in to join then  is  200 mm  ok

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## mullfitz

anyone have any ideas of how i could join the same material together and use the above metal for joists and sit them on  top of the bearers  could i use a  angle bracket or self taping screws into  the metal and join them together

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## phild01

I would use tek screws over self tappers.

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## mullfitz

> I would use tek screws over self tappers.

  
Why is that ?

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## phild01

http://cdn2.hubspot.net/hub/446422/f...=1427382383830 
Often things on the forum here, I find the terminology gets far too generalised.  When speaking of self tappers, these are the screws that spring to mind: 
Tek screws have a better holding thread and the variety is greater eg   What are Tek Screws | Self Tapping Fasteners

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## DavoSyd

> Tek screws have a better holding thread

  in what way?

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## phild01

> in what way?

  I guess it comes down to what self tapper you are referring to.  I find the garden variety ordinary.  The self drilling types seem to have a generous variety available to suit a given purpose.  The tek screws precisely drill the correct hole for positive grip and are best for stainless steel.  I have used tek screws in a variety of situations where a 'common' threader would likely disappoint me. 
Try them out and see what you think.

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## DavoSyd

ah i see... i will take a closer look when i am in the hardware store next, 
I just assumed that a self-driller thread (being essentially a self-tapper) was the 'same' as a normal self tapper - but i think i was being a bit blinkered regarding the range of options...  
i really just hope for OP to be safe and alive etcetera...

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## phild01

> i really just hope for OP to be safe and alive etcetera...

  Not sure what the OP is getting themselves in for here!

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## mullfitz

Here  is the original item I have got and then I have taken them apart to use

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## DavoSyd

lol, did you keep the bolts?

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## mullfitz

> lol, did you keep the bolts?

  Of course and the wheels  :Smilie:

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