Quick question about air bricks

[Jim_cam]

Hi -- I've looked through the archive but can't find an answer to this particular question, so I apologise if it's a repeat. I've just moved into a mid-terrace Victorian house (c.1880) and I'm fixing up the suspended wood floor in the downstairs; this includes putting celotex in between the joists, moving out rubble from underneath, etc. There's one air brick in a good position at the front of the house; there's none at the back, because the suspended floor doesn't go all the way back there-- there's a 70s or 80s extension with a concrete floor added on instead. Is one air brick sufficient to ventilate the underfloor area? I don't really have the option of installing another one anywhere other than the front, and that seems a bit pointless (maybe I'm wrong).

By the way cheers for all the excellent advice in other threads -- very helpful.

 

[Safety First]

You need at least two to make a through draft occur. Opposite ideally... There's calculators out there (or people that can quote standards here!) that will allow you to see how far from proper, your situation is....

Maybe there are some low voltage fan things that you could set up to pipe air out of the far end... there must be some solution...

People did some awful things to houses in the 80's... buggers buried my house (4 inches over DPC and blocked air vents) in the 80's..

 

[John D v2.0]

As long as you can avoid dead zones it's fine. By now most old houses have insufficient ventilation, not that they were ever to modern standards. I've heard people talk about using redundant chimneys to ventilate dead zones so it's worth trying if you have one.

 

[Jim_cam]

That's helpful, cheers! I've finally got to the back of the room and it seems like there is actually a pipe to a covered over air brick at the back of the extension -- looks like I can clear it out to ensure that I've got a sufficient through draft. Now to address the joists -- a nightmare for another thread ...

 

[John D v2.0]

Yes in theory the air bricks should be ducted through. In practice we had 3 ducted through (one remaining now) but the two that are gone there was concrete leaked into the pipes and blocked them up. The one at the front isn't connected even though you can see it there so probably the same issue.
See what you can do.