Why do concrete floors need ventilation!?

thegentleway

jj_home_80 said:

Yeah, it’s a bit confusing – even with beam and block floors, ventilation’s usually still needed. The void below is there to stop moisture build-up and help with airflow, especially in older properties. Blocking off those air bricks completely can cause damp or mould issues over time.

If you're raising the patio to threshold, best bet is to use something like vertical air brick extensions or telescopic vents to keep airflow without blocking them. Seen people do it without and regret it later. Worth doing it right the first time!

Sorry but I don't think it's needed for concrete floors. Mould isn't going to compromise concrete and with no air brick you can't breath it in... I can see a case for ventilation if you live in a high radon area or if you have wooden floors of course. 

I can't use vertical brick extensions/telescopic vents as bifolds span the whole width of the house. We're going to duct them underneath the patio but yeah I don't think it's actually needed.