Does this external soil pipe require mortar or some other filler material to seal the pipe?

[John D v2.0]

What about if I asked him to install a rodding access point in the vertical pipe from the first floor, just above the first elbow?

You could but it still wouldn't comply with building regs. You might get away with all sorts, we had a waste pipe going up hill for a couple of years, and we just chucked drain cleaner down every few weeks when it ran slowly. But we fixed it as soon as we could, and we wouldn't design it that way even with a rodding point

 

[Hugh Jaleak]

What about if I asked him to install a rodding access point in the vertical pipe from the first floor, just above the first elbow?

It'll take a brave person to open that when the upstairs WC is bubbling away as the stack is blocked.... If the stack is going in through the wall, and turning 90deg again to drop down, then its not a major job to reconfigure so the stack goes directly down to the drain. Pretty likely the drain comes straight back through the wall at that point anyway, so only a case of digging down, finding it, and making a proper connection there.

 

[PipeDownSoldier]

It'll take a brave person to open that when the upstairs WC is bubbling away as the stack is blocked.... If the stack is going in through the wall, and turning 90deg again to drop down, then its not a major job to reconfigure so the stack goes directly down to the drain. Pretty likely the drain comes straight back through the wall at that point anyway, so only a case of digging down, finding it, and making a proper connection there.

Right I’m a bit worried now. In all likelihood, what are the chances of this thing getting blocked?

How big a job to reconfigure if the soil stack goes down into concrete?

 

[Bosswhite]

Right I’m a bit worried now. In all likelihood, what are the chances of this thing getting blocked?

How big a job to reconfigure if the soil stack goes down into concrete?

100%

Get the builder back to do a proper job.

 

[ReganAndCarter]

So there are now 2 no. 90° bends in the wet section at the base of the stack?

It's the no. 2s stacking up that will be the big problem.

I completely missed the fact that this is at ground level. Hmm. Unless the whole family can be persuaded to live on a diet of prunes and draught Bass, it will always be a problem the way it's been done.

 

[John D v2.0]

As a minimum change the 90s to 45s or less to make a gentle change of direction

 

[Hugh Jaleak]

Building regs frown on bends in the wet section of a stack. There are times when its unavoidable, but then slow radius bends should be used. The bend they've used in you picture is one of the tightest 110mm bends I have ever seen, solid are going to hit that at some speed, and are going to spatter everywhere inside the pipework, and create an unholy mess, before eventually blocking the pipe.

Long radius bends are used at the foot of a stack to allow the discharge to gently sweep round into the drain, and not cause a problem. Get it changed to a proper setup, any cost saving now will soon be forgotten when you get the bill for opening it up to sort out the mess when it blocks up.....