Suspended ground floor ventilation requirement

[jmn123]

1930s detached house.
Room is 4.81 x 3.05m.
Suspended wooden floor. About 2ft between floor and ground.
Room has 2 nine by six inch vents at either end. (4 in total). These would be the original vents installed when the house was built.
Room is cold in winter. Is the current amount of ventilation excessive?
There is also a similar sized vent at first floor level. No gas or solid fuel appliance in room concerned. Is this actually needed?

 

[KenGMac]

jmn123, good evening.

I take it there are two vents front and back?? or two adjacent sides?

As for the air brick at high level? is it positioned "within" the ground floor, floor to ceiling height? any indications of an internal vent?

Ken.

 

[jmn123]

Hi
2 vents in the front and 2 at the back.
High level vent is within the floor. No vent in the room itself.Ceiling height is about 2.5m. There may have been a gas fire in the room at some point in the past but this was removed before we purchased.

 

[oldbutnotdead]

Presumably the 2 vents at each end are in the floor void (so under the floor boards)? If so then yes they're needed, if the room is cold then look at insulating under the floor (2' clearance means one can fit from below)

 

[jmn123]

Yes they are but I wondered if just one each end would be sufficient.

 

[KenGMac]

just one each end would be sufficient.

Not really, because there tends to be a direct flow of air from the front air brick to the rear, it "can" leave a few dead spots where moisture can build up.

As oldbutnotdead above, that is an option???

Ken.

 

[jmn123]

Yes-looks like insulation is the best way forward. Any suggestions as to the best method?
Is the first floor vent needed?

 

[KenGMac]

There are several threads in the Forum on this topic, for example there is a recent one, https://www.diynot.com/diy/threads/filling-subfloor-with-insulation-beads.537204/#post-4534371, that may be of interest??? except you should be able to access the under floor void, rather than lifting the flooring???

As for the High level vent? appears not to be a requirement, suggest you consider checking [if possible] that the vent does not just vent the cavity not a particularly good state of affairs a cavity is supposed to be a sealed, un-vented void.

Suggest you consider removal and infilling externally with brick??

Ken.

 

[jmn123]

Thanks to both of you.

 

[KenGMac]

Something to consider.

Also if you insulate the floor in one room, how about the rest of the ground floor rooms?

 

[John D v2.0]

Yes the under ground floor is effectively outside/unheated spaces so the solution is a good layer of insulation and keep plenty of air flow on the cold side. Nowadays one air brick every couple of metres is the usual recommendation.

 

[JohnD]

Room is cold in winter

Does the room have bare floorboards with no carpet?

Is the fireplace open?

 

[tony1851]

Apologies if I've missed something but do you have any form of heating in the room?
Also, what you don't want to do is block up any of the vents; a draughty sub-floor space gives a healthy floor.