Air leak from floor drain

I did an energy audit in the brand new house, testing its air tightness with the “blower door”. The house has two floor drains in basement: one near furnace and another one in cold room. The one in cold room was “leaking” air enormously. The one near furnace was totally air tight. My first suspicion for the cold room floor drain was that there was no trap or the trap was dry. We removed the cover from the drain and looked inside. I saw the water in the drain but there was a large hole in the drain wall, in the concrete, above the water line but below floor level. I assume the air was coming from the space under the concrete floor. Does anybody know if this is a correct arrangement? Or is it something missing here? There was also a sewer smell from this drain when the “blower door” was running. Sorry, I did not take a picture.

There’s nothing good coming out of that drain: Sewer gas we know, and radon possible. The owners need a plumber.

Jim King

Pressurizing/Depressurizing the internal air of the structure can break the trap seal. The fact you ran the test could be the only reason you may have smelled sewer gas.

If there is no sewer smell without the test, there should be no problem, and it could only indicate that the trap needs to be filled with a bit more water.

The hole in the pipe above the trap should be noted and sealed, but it should otherwise be of little (plumbing) concern.

Just FWIW, I’ve seen people drill holes in the side of floor drains to allow run off water to drain from under the slab and go down the sanitary sewer.
(not saying it is right)

And I think this is the case here too. Again I would really like to know if this is correct arrangement or not? Since the house is brand new (less than 4 months old), this obviously was done by the builder. So I try to understand the purpose of this and whether it is correct or not. As for the sewer smell, I realize that it was there due to depressurization of the house, however the other floor drain was totally fine. So something “smells” not right here! I’m grateful to everybody’s response but I’m still looking for more definitive answers (maybe even in lieu of the current plumbing/building code in Ontario). Thanks again.

Well the hole above the trap could be from an improprely installed trap primer, most areas and code require proper fittings for trap primer line to trap.
Regards Bill