Creating airflow with sleeper wall

[getafix the druid]

Morning all

I've got all the floorboards up and am replacing joists with rot and woodworm

The joists rest on several sleeper walls that run the whole length of the room, with a wall plate on top. I want to insulate under the boards. The problem is that would essentially cut off airflow to most of the room

Would it be possible to remove a few bricks along the sleeper wall to encourage airflow? If not I'm thinking of just not insulating on the bits above the sleeperwall to let air pass over.

Dont really want to go to the extent of knocking the sleeper walls down and rebuilding honeycomb sleeper walls

See pic, the air brick in this room is in the top left, in between the two sleeper walls in the corner

Thanks in advance for any advice

 

[Flyfisher]

It's certainly possible to remove some bricks from those sleeper walls. We have a suspended floor where the joists are supported on brick 'pillars' rather than sleeper walls, which leaves the whole underfloor space very open while the floor itself feels solid underfoot, so it certainly can be done.

As for improving ventilation, I feel sure it would help but an even bigger improvement would be achieved if an additional airbrick could be inserted somewhere, preferably on a different wall to the existing one. With a single airbrick the space has to 'breathe' in and out through a single opening but with two airbricks there can be flow of air. Think of a length of pipe closed at one end compared to a pipe open at both ends - the latter will be far easier to ventilate (ie change the air inside). With two airbricks on different walls, any wind will create small pressure differences around the building that will help drive fresh air through the underfloor space.

It's not easy to see from the photo if an additional airbrick would be easily possible to insert but its worth considering.

 

[getafix the druid]

Thanks for the reply

There is another air brick on the wall about 3m behind me when I took the photo. The problem is theres about 6 of these full length sleeper walls between the two!

 

[Flyfisher]

In that case, removing a few bricks from each sleeper wall should greatly improve the underfloor ventilation.

 

[Tazbert]

just wondering, are you planning to insulate the full depth of the joists? If not air should be able to get over the top of the walls under the insulation (area of airbrick will be a lot smaller than total area between joists unless you really make the gap small).
Maybe consider some sort of support to ensure the insulation doesn't drop and block the airflow?