I have a concrete column using 16mm rebars. The column needs to be extended (and of course the rebars) for the 2nd storey of the house that is being built. Should the splice be welded or surrounding the splice with 6mm spirally will be fine?

Please do not suggest me to contact my contractor or engineer since the reason I posted this question here is because that is not possible in my case.

I only need some ideas.


  • 2
    This can not be done in my state with an engineering stamp on the plans. – Ed Beal Sep 19 '16 at 18:52
  • 1
    An extension can be done, but a) You don't have the equipment and b)None can reasonably make a suggestion to the specifications in your situation with out detailed plans and pictures (ie, what and engineer would do). Sorry. – Chris Sep 19 '16 at 18:59
  • @Chris, in general, do you need to weld the splice when extending the rebars in a 35x25cm column composed of six 16mm rebars? For example, if a single column's height is currently 3 meters and you plan to extend it to 6 meters height to support additional storey. – user1764381 Sep 20 '16 at 13:20
  • In general your cheapest option is to demolish the existing column and re-build with new specs. – Chris Sep 20 '16 at 21:56
  • @Chris May I know if you can share a link to a doc or to a building code that mentions about the need to weld a splice or that mentions whether welding a splice is needed or not? Thanks – user1764381 Sep 21 '16 at 18:54

Historically rebar has had high carbon so so very likely to crack if welded. Modern rebar is lower carbon but is not intended to be welded. Depending on the composition of the rebar you have a fair chance of no cracks in the weld zone. I would stay with the traditional wire joint.


Well, the structural strength does not come from the "join in the rebar" rather the cement column with rebar in it. In many construction sites, the join is done with an overlaping join, with simple wire stays to hold the rebar in place until the cement is cast.

welding is convenient, since its a way to permanently affix the new bar.. If you did, i would weld with an overlapping joint, and not a but joint. --

People would be reluctant to provide advice over the web, since there are many factors regarding the specific column in question (load, thickness, compression force, torsion force etc... ) so, it would be best to consult a pro..

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