Earthy smell in conservatory/living room

pinkclouds21

Just wondering if anyone can shed some light please.
Father in law built a diy conservatory on the back of my living room (which is the only point of access to the garden) in December. The last couple of months I've been smelling a sort of musty earthy smell, made worse when it rains. I thought it was just isolated to the conservatory, but if I walk into the living room from the hallway I can smell it also. Sometimes the smell is very apparent, and sometimes I can't smell it at all. I keep all the windows and doors in the living room open and a window in the conservatory open during the day. I'm wondering if it's coming from the floor as I can smell it very strongly when I'm cleaning down there. The base is a durabase with steel joints, polystyrene insulation with chipboard as the floor base. I'm at a bit of a loss on how to find the cause of the smell, help appreciated!
Thanks

TheCyclingProgrammer

Did you build the conservatory over the top of your airbricks, meaning your subfloor is no longer properly ventilated? If so that would explain the musty smell.

pinkclouds21

I've just had a look and there are 2 untouched, which are on the exterior of the house (theres a foot or so between each side of the conservatory and the fence either side). However theres one inside the conservatory, which I'm pretty sure is partially covered

Aylesbury_Duck

I think thecyclingprogrammer has diagnosed the problem correctly. You've probably got a reduced airflow as a result of the blocked airbrick.