On another thread #15519 I have detailed the beginnings of my travails with a screed failure localised to my entrance door. I continue these here since they now involve a gas pipe and likely building regs too.

Further to the cavity-crossing work, I removed more floor covering, uncovering cracked screed as I progressed, stopping only when the cracks did. This identified the pipe for the house gas supply as a nucleation point for screed failure.

This is a 27mm diam pipe, crossing the entrance hall, and resting directly on the blocks of the beam and block floor. It serves a boiler and gas hob. The pipe was flanked by 25mm EPS, and also overtopped by the same, before the screed was poured/laid. The overtopping was not a good idea, reducing the (otherwise 40mm thick) screed to 18mm, and making of the pipe a fulcrum for the 500mm lever of screed to the front door - hardy surprising the screed failed over the pipe.

Question is re;fixing this and what particular regs apply to such gas source pipes? It is sleeved through the wall. With generous ventilation gaps both within the sleeve and outside it; any reason not to reach for my Soudal AWS airtight foam to fill those gaps?

The flanking EPS stops 20mm short of each side of the pipe and that gap filled with very fine granular materials. This looks slightly more structured than the usual lackadaisical construction quality I'm dealing with in this house. Is this detail regs related?

Likewise the overtopping with EPS - this is a shockingly bad idea in terms of its impact on screed longevity - but was it done as per some aspect of regs e.g. perhaps the pipe ought not to be encased in screed directly?

Can anyone here point me in the right direction on these details? Is the filled flanking gap between pipe and EPS required? And the overtopping EPS? Or am I ok directly to embed that gas pipe in the new screed without any such flanking gaps or overtopping EPS?

I can imagine the pipe (steel) will be subject to thermal expansion/contraction - which wouldn't do much good to any screed bonded to it; is preventing that bond the objective for the flanking loose fill gaps and the EPS overtop?

Thanks. And happy to hear any other tips from those practiced in the art which will almost certainly come as news to me.

Yes is mains gas.
Yes Wow that's quite a diversity of advice you received.

This pipe routing quite possibly looks like an afterthought but if so likely to be the case also in the ~100 other houses on the estate.

Will track down my gas-safe certified boiler installer and enquire whether that cert. qualifies him on such details

From the technical advice section of GasSafe (0800 408550 #4) I learn of the contents of BS6891 as amended 2015 & 2019

It is indeed acceptable to bury such a pipe in screed provided said pipe run is either parallel or at right angles, is suitably protected against corrosion, and is covered by screed of at least 25mm depth.

Suitable protection against corrosion include any of factory finishes intended for that purpose, wrapping in PVC tape maintaining a 55% overlap at everyturn, bituminous paint, or densotape. Densotape themselves recommend protection of their tape with a pvc overtaping for good measure.

For new such installations trackpipeCC is recommended.

No such requirement was mentioned. Doesn't mean there isn't one

I'd say that was such a no brainer that I will mark it
s location with suitable tape on screed surface much as I mark water pipe runs on chipboard flooring