Foul smell in house

johnnybrando1981

Hi everybody, first time on this part of the forum, but used the forum for lots of other financials previously. After some advise please...
Last Thursday approx 10pm I noticed a smell whilst watching TV, that smelt like cabbage or sprouts. It does not smell like human waste. Wasn't pleasant, went to bed, got up next day and it was worse. I have cleaned and bleached the entire house, it is still here. I think I have identified where the smell is coming from but I dont know what it is or how to resolve. My house is a 1930's terrace, the main house has suspended floor with approx 2ft space beneath. It was originally a 2 up 2 down, but was extended by the previous owner, so the old rear external wall, has been knocked through and the kitchen is in the extension. Extension has a concrete floor. The smell is coming from when my internal floor meets the original exterior wall and the extension meets. If I get on my knees, the smell comes from where my wood floor meets the skirting board. I can get under the house, there is a small access hole under the stairs, and then would need to crawl through another space into the back of the original house to investigate further. I have not done this yet, as I would rather have my fingernails removed, but I will have to if the smell does not subside soon. I have put bicarbonate of soda down on the floor and will go under tomorrow. Both neighbours report no smell. Only thing different in mine is heating gone on more often, its colder etc etc.
From my perspective, there is no access for animals or rodents. The soil pipe for toilet does not go that way, but previous owner thinks an old drain 'may' run there. Central heating pipes run under the floor where it smells. Does anybody have a suggestion as to what it cold be, resolution or options, as it is driving me insane and rather unpleasant indeed. 
Thank you in advance 
JB

Homer_home

Could be anything , leaking waste, rotting animals to name but a few....

My advice ;
Grab a torch and get crawling

Guessing doesn't get rid of the smell...

DevilDamo

Does it smell like damp? Sounds like your existing floor is timber and assume vented? The new extension floor is concrete and assume not vented? If this is the case, ventilation should have been ducted through the extension to the new external wall.

johnnybrando1981

DevilDamo said:

Does it smell like damp? Sounds like your existing floor is timber and assume vented? The new extension floor is concrete and assume not vented? If this is the case, ventilation should have been ducted through the extension to the new external wall.

I guess I may see when I go crawling tomorrow 🤢 thank you 

Doozergirl

DevilDamo said:

Does it smell like damp? Sounds like your existing floor is timber and assume vented? The new extension floor is concrete and assume not vented? If this is the case, ventilation should have been ducted through the extension to the new external wall.

And if it is vented, an average airbrick hole is plenty of access for a rodent 😬

frogglet

I would say dead mouse or rat. They get everywhere.
Can't you pull a floorboard up rather than crawling under the floor?

johnnybrando1981

frogglet said:

I would say dead mouse or rat. They get everywhere.
Can't you pull a floorboard up rather than crawling under the floor?

I went under! I have wooden floors. Anyway it was vile down there, but everything looked clean, no leaks, no animals I could see, no droppings. Weirdly one of the kitchen cupboards (solid wall behind, concrete below) Stunk! I’ve cleaned it, and under it, left it empty but I have no idea why so bad from
there. Only things in there are Tupperware and a few ceramic dishes etc. Nothing smells it’s bizarre. It does not seem as bad last day is so but there is still a smell. I am hoping it just goes away. Only way in for a rodent is air bricks and holes are not much bigger than a screw head, so maybe a mouse but doubt a rat. No sign of animals anywhere and no smell from under the house at all! The plot thickens!!

frogglet

Has the cupboard got a back on it as there might be a mouse stuck behind it?

johnnybrando1981

frogglet said:

Has the cupboard got a back on it as there might be a mouse stuck behind it?

It has but, I’ve taken off and taken the kick board off and nothing. 

coffeehound

johnnybrando1981 said:
Weirdly one of the kitchen cupboards (solid wall behind, concrete below) Stunk! I’ve cleaned it, and under it, left it empty but I have no idea why so bad from

 Sounds like it could be a cold spot and so attracting condensation.  Fitting a PIV fan would help with humidity and also push smelly underfloor air outside and keep it from leaking indoors.

Debran

They say a mouse can get in through a hole the diameter of a pencil.  From experience, they stink for a few days after they die but this fades with time.

The only other thing I've had (long time age) which pongs is a faulty electrical appliance plug.