Moving an incorrectly placed soil vent pipe

[Bancroft]

After putting the 300mm thick concrete slab down we started building up the ICF walls - only for me to note that a SVP was in the wrong place.

 

It comes up about 500mm out of position and half way across an internal doorway...

 

Neither the surveyor or builder have any idea how it happened but it did.  Builder and SE are now scratching their heads to see how best to resolve the issue but I thought it might be worth getting some opinions from the experts here.

 

It clearly needs to be moved but I'm wondering what will the best way to do it while still maintaining structural integrity of the slab and insulation?

 

To me, there look to be 2 options:

 

Option 1. There will be 150mm of insulation on top of the slab so the pipe might be able to be hidden within that.  But, to contain the pipe within it, it would need a right angle bend and would result in loss of insulation around the pipe run.

 

Option 2. Cutting back into the slab would mean cutting out quite a large area of concrete/rebar and through the DPM to add an additional piece of pipework to come up in the correct position, then resealing the DPM, and adding rebar and fresh concrete back into the hole.

 

Would the loss of insulation around the pipe in option 1 be an issue once screed has gone down and UFH installed?  This particular SVP serves the utility room so will only have basin/washing machine waste running through it so should be able to deal with the 90 degree elbow?

 

Would option 2 penetrating the DMP be a point of future weakness, or would a good amount of mastic taping and sealing be sufficient to ward off problems?

 

My feeling is we should fix this properly (option 2) but I can't help thinking that might be creating more problems for the future.

Really not bothered about how much work it will be for the builder - it will give him time to reflect on the error of his ways while he sorts it out and (hopefully) won't do it again the future.

[JohnMo]

Option 3 move doorway