Kitchen extension and lack of air bricks

pieroabcd

Hello,
10 years ago the previous owners built a kitchen extension.
They passed through the Council from the start with all the paperwork, had an engineer do the calculations and years later, before selling, they had the certificate of completion and retrospective approval as PD.

Looking at the exterior of the kitchen extension I can't see any air bricks. There's a long grate at the base to collect water, but I don't know if it also provides ventilation.
The eng plan seems to mention that the base is made of solid concrete. It doesn't seem to use wood joists for the floor.

At the front of the house there are 2 air bricks, one under the bay window and one near the door, a couple of meters apart

Are they enough to provide enough ventilation for the original subfloor of the house or must there be an uninterrupted airflow from the front to the back of the house (as it must have been the case before they built the extension)? What's the correct practice for cases like this?

I began to wonder because the space under the stairs (now a cabinet for tools) always smells a bit of musty. I thought that the nearest airbrick would be enough to ventilate it, but who knows.

Thanks

stuart45

They should have used ducts in the concrete floor to keep the cross flow of air through the timber floor.

pieroabcd

And of they haven't, am I risking rotting?
Is It possible to provide additional ventilation in some wsu5?

stuart45

Have a look at at current thread on the house buying, renting and selling.
Buying a house with major problem not picked up by building control.

pieroabcd

Nevermind. I've found the mention of the air ducts in the planning application and for the first time in 1 year I've also seen the 2 air bricks

Excluding this factor I wonder what is causing that smell of musty under the stairs,