A reader's Concrete and Concreting question: Long concrete stairs.?

Jeff M.   from   kamloops, BC, Canada   had this long concrete stairs. question.

I need some advice on formwork for a set of concrete stairs with 2 landings and 3 runs. How do i brace this?

Bill's answer

Hi Jeff, It sounds like you want to form it up and pour it in one hit, and I am guessing that it is all in one direction, not like in a stair well situation.

• I'd be using something like an Acrow V shore system if it was available, similar to what I show on my concrete formwork slabs page.
• The stuff that is self bracing. I would set up the whole of it with these frames, not just the landings, so that it is all tied together.
• You'll have some fun setting the slope but the ability of these system to connect solidly together is the main advantage.
• I would still be using a few extra lengths of scaffold pipe as braces,clipped tightly to the frames.

• If you have no frames available, I have done a few jobs in the early days just using scaffold pipe alone, with screw jacks top and bottom, and all the load bearing joints double clipped.
• That is an extra clip, fixed under the normal one, to stop any tendency to slip down.
• Again with plenty pipe bracing as well.
• It is also fairly common to join ordinary steel props together, they will take the weight, but they again need tying together with horizontal scaffold tube and clips to stop them wanting to bend. Once again,brace with a few diagonals.
• If you have a masonry wall at one side, and if it is solid you could also tie in to that with a few expansion bolts and putlog cleats.

One other thing that I have done in the past on a real tricky job, is sketch out what I was going to do, and take it to an engineer for him to run the calculations and confirm it OK. It is a small amount of extra cost for the peace of mind.

It really depends on your situation. I can only generalise with the information given. Send more details if this answer seems a bit vague.