Suspended timber floor ventilation

[Garyf123]

Hi!

I know this topic has been covered many times but can’t quite find what I am looking for!

I have just purchased a 1850’s brick built end terrace house. It has front and back walls with approx 4” cavity and end wall is solid (double brick thickness I think). I am fitting wet UFH to living room, dining room, kitchen and office. The kitchen and office are Extentions and have solid floors with vents into cavity’s.

The living and dining rooms have suspended timber floors so I have been underneath and filled the joists with mineral wool and covered the bottom of the joists with breathable membrane. Whilst under the floor, I noticed there was no obvious means of ventilation! The previous owner found some damage to a section of joists near the rear of house and cut out/replaced with new treated timbers and new section of floor board but did not add any ventilation! The rear of the house has the Extentions so no way of adding vents there. The front of the house has one double brick vent but just into cavity. I have core drilled a 120mm hole through both courses as low as I can (the ground level falls away from house) and installed a length of soil pipe into my joist void and insulation and elbowed it down into the floor void and fitted a grill on end. I am now stuck as I cannot provide correct cross ventilation because of rear Extentions and the end wall has the joist tight up to it so cannot core drilled through. My idea is to take a brick out through both courses(solid wall)at skirting board level, then fit a telescopic vent through from outside, exiting in inside above floor and sending it down through floorboard, insulation and membrane into floor void and sealing up again by making a small insulated box to cover telescopic vent ( it’s in small recess at side of fireplace and can be easily hidden by plant, cupboard etc. 

not ideal but I am working on any ventilation is better than no ventilation!

Any thoughts please?

 

Gary.

 

Edited May 16 by Garyf123