We recently bought a house in the UK built on 1936. The house has been refurbished and extended a few times over the years.
With the cold and moist weather outside, the first thing we noticed was a draft coming from the kitchen, causing the temperature in the kitchen and the hallway leading to the front door to be lower than the rest of the house. And because the thermostat is in that hallway, you get a super hot first floor and an ok-ish ground floor. Tracking where the air comes from, we spotted some vent bricks lower the the floor level and higher than the ground outside.
After some research online, these were apparently used to ventilate suspension wooden floors on the ground floor from moisture and mould. However, as far as I can check and to the best of my knowledge the floor is from cement now on the entire ground floor. I guess when it was originally built it was wooden so this made sense.
Am I safe to block all these foundation vents around the house? Or even just that one would make things better I guess. What else would you advise to deal with this?