Soil pipe vent no longer external- second opinion needed please

[Chattercino]

We are having a new bathroom and I’ve noticed the plumber has cut the vent to the soil pipe (which used to go right up through the roof). It’s now just slightly higher, if not same height, as the toilet (at a guess as toilet isn’t in situ yet). He’s put some sort of venting cap on the top of it. Is this going to be ok? Perhaps this is just a temporary measure and he will add more height to it later (but it doesn’t look to be the case- and I can't ask him until Monday). Should I ask him to reinstate full vent or will this be ok?

I expect he's going for a Durgo or similar.

They seem quite popular with bathroom fitters who like to hide them away and box them in.

In a few years time, when it sticks and your bathroom smells of sewage, the plumber will smash the tiles and break the wall open to get at it.

Can you guess my opinion?

AFAIK there are two types of venting for waste pipes, one is to let air escape so you don’t get bubbles coming up when you e.g. drain your bath and the other is to let the sewage gases vent out.

The latter really should go out through the roof really. The former doesn’t always, but I personally insist it should go out of the house regardless, as I don’t like the idea of having them in the house.

If he's going to put in a durgo vent then you need to check where you are in the line of drains with your neighbours and if anyone else has one. Our builder recently suggested it but building control said no. Instead we have a vent that is flush with the roof and looks like a roof tile.