Mystery smell

[MagpiePi]

There is a noticeable smell when you are a couple of steps up from the hallway and I cannot work out where it is coming from.

For background, I had new carpet in the sitting room about 6 weeks ago and the damned cat pissed on it so it did smell in there until I got it professionally cleaned.

The smell on the stairs is similar and I thought the cat had pissed in the hallway somewhere but I have had new carpet and underlay in the hall and stairs, and it has all been painted too and the smell is still there.

The only thing I can think of is that there is a leak in the waste pipe from the toilet but there is no smell in there or anywhere else, and it isn’t a sewage smell, more like a slightly burnt smell.

I can probably access the space under the stairs/toilet by knocking some bricks out of the outside wall (the ground outside is about a metre lower than the ground floor) but I’d rather not just yet!

Any ideas?

Have you a light fitting/lamp anywhere in that area? My dad had a similar slight burnt smell in one spot and it was the white plastic on the fitting beneath the bulb 😐

After changing the lot and putting a weaker bulb in it was all fine.

There are some LED(?) ceiling spotlights in the hallway but I don’t often turn them on and they are more towards the front door.

There is a wired in smoke detector/fire alarm above the bottom of the stairs - I wonder if it is that? will investigate!

What is the smell like?dead mouse? Sewage? Damp? Fishy smell?

A slight burning smell, but it does have a slight cat pee tang to it.

Thinking about it, the smell is strongest when my head is level with the ceiling of the hallway. I’ve disconnected the smoke alarm now so will see if that helps.

Watching with interest as I have the same!

Disconnecting the smoke alarm hasn't helped :(
I will turn off the ceiling lights at the fuse board.

We once had a similar mysterious smell and it was an uncapped drain pipe. Resolved immediately once it was fixed.

A fishy/ammonia/urine like smell can be from burning plastic or overheating plastic. I'd be suspicious of the wiring in that area.

I'm not convinced a professional clean will have removed the cat wee from the underlay/floor underneath.

I would pull it up and see if the smell is floating along from there.

The cat pee was in the sitting room and the cleaning has definitely removed the smell from there.

There is new carpet and underlay in the hall and on the stairs.