Can’t get rid of smell in spare room

[shadesofpink]

I moved into a new build earlier this year and since moving in the spare bedroom smells- it’s kind of a musty/stale smell. I’ve had the carpet cleaned, aired it out (the windows are constantly open when we’re in the house) deep cleaned it multiple times and we had a snagging survey done which checked for moisture/damp and leaks which found nothing so the smell can’t be related to that.

Any tips to get rid of it? We can’t even put furniture or clothes in it at the minute because of the smell!

Something is off. As it is a new build, keep on at them until it’s sorted.

Is there an en-suite and the traps aren't full of water

Moisture in the wall cavities, the inner window frames, under carpet, ceiling holding moisture from a roof leak? Some new builds, due to being locked up prior to sale, have trapped moisture / grow mould and this sits on the plaster board, grows into it, as a nice food source for the mould. A possible fix is to coat over the damp, but that can trap it in and it could have been done on a new build, it would not be the first or last time!! I would look at the room from the outside, try to get into the roof cavity if possible, look at any down pipes etc. and whether any pipes are concealed in the wall cavities too. Also the carpet could be holding the smell, so not damp but mouldy. Buy a damp meter and check for yourself.

Are any of your plumbing vents not connected or configured wrongly?
Aren't builders required repair defects for a period of time?