Extending a step

Forgive me if this sounds daft, but here goes


Due to a burst water pipe under a concrete floor I have decided to re run the pipes above floor level. The problem I have is that the pipes now run in front of the step inside the back door, I need to extend the step over the pipes. I have covered the pipes with some metal channeling and intend to concrete over this to extend the step. Should I add PVA into the Cement mix to help this new bit bond to the original floor? I have done a rough diagram below to try and explane this

I'm curious, why do you have a step inside the back door?

Anyhoo, you may find it difficult to get a successful, crack free (masonry) join particularly as it involves a hollow channel within the extended step.

I would need to see a photo, but i would be thinking of using timber in front of the step to form a channel around the pipework then lay plywood over the existing step onto the timber cradling thus covering the whole show. Or tile the step ensuring the join is adequately lapped.

The above suggestion is obviously subject to height constraints and the like.

The intention is to tile over the extended step. I have no idea why there is a step inside my back door.

Adding PVA to the mix is ok then?

I don't think pva in the mix will give a sufficient bond to hold the new step extention, long term. It needs to be anchored
If this is the way you plan to go anyway, i'd drill some holes, (half a dozen or so) into the original floor, under where the new step will be located, and put bolts into the drilled holes, and leave them protruding a couple of inches, so when you pour the concrete step extention, the bolts will act as a mechanical key, holding the step secure. You could also do the same (carefully) with the riser,,, and drill 3 or 4 holes into the front of the original step, insert protruding bolts, and again, they will permantly anchor the step, this time along the top.
If you do drill into the front of the old step,, angle the drill slightly downwards, and don't drill too near the top, maybe a couple of inches below it. Wet/pva the surface of the original floor/front of the step, just before you pour in the new step extention.