We have recently moved into a new house and have since noticed that there is a sewage like smell coming from under the bottom step. This smell is not constant it comes and goes and is more apparent when the central heating is. Originally we thought it was a dead animal of sorts but since cutting holes in the bottom step there was nothing there apart from the floor boards. The bottom step appears to have some vents in them which were covered by the carpet and the air brick for the floor has been covered up at the front of the house. We poured a strong bleach down the drain to see if there was a blockage but there was not a smell in the house of the bleach.
Any help would be appreciated

The bottom step appears to have some vents in them which were covered by the carpet and the air brick for the floor has been covered up at the front of the house. What bottom step? Where's it located? What's a "aiur brick"? Vents! Describe them. Are they plumbing vents? If not then what are they venting? City sewer or septic tank? Have you opened upo the step to see what's underneath? Let's have more details. Regards, Tom

It is the bottom step in the lounge leading to the first floor, The vents were not plumbing vents they were just metal grids on the bottom ridge of the step, I do not know what they were for, an air brick is a brick which allows air to the wooden floors to prevent damp etc, it is the city sewer not septic. I have opened up the step which just reveal the floor boards, I have not removed these just yet

I have opened up the step which just reveal the floor boards, I have not removed these just yet You're on the right track. Let me know what you find under the floor boards. I'm really interested in what that step was venting. Good luck, Tom

Possibly a floor drain that got covered? If a floor drain got covered, the trap has most likely dried up allowing sewer gas to enter the house. If you do find a floor drain, make sure that it doesn't get covered up again, or if you want to cover it, make sure to plug it permanently. Im also interested to know what you find.

We have just had a friend visit the house and he noticed that we do not have a stench pipe? Are these quite easy to fit i.e.. Cost, installation etc

We have just had a friend visit the house and he noticed that we do not have a stench pipe? Are these quite easy to fit i.e.. Cost, installation etc
You say;
We have recently moved into a new house Is it still under the builders warranty ? This dwelling was constructed and passed inspection without any vents? That's pretty unbelievable. Are there any pipes coming out of your roof? Let me know. Tom

The building was built in 1890 and the toilet appears to be a new extension, I shall have a look when I get back in regards to the pipes. We have also had the drain people round to check for blockages but they have not found any