Cavity wall and airflow.

[Allex]

I have a block built property. It has unfilled cavities. There are vents through the inner wall to outside wall air bricks under the floorboards which work well keeping it all dry. The walls are built on a concrete platform with 500mm between floor joists and concrete. I am considering filling the cavity walls sometime but to prepare I am thinking of fitting a channel through the slot in the inner leaf to butt up against the air brick so that if and when the cavity is filled we do not block the underfloor airflow. Is this likely to cause condensation in the cavities due to the air flow being blocked from spilling in there as it does at the moment?

Thanks.

 

[JohnD]

No.

 

[mrrusty]

So a property designed to have ventilated cavities you are going to convert to unventilated? Where does any interstitial condensation go?

 

[JohnD]

So a property designed to have ventilated cavities you are going to convert to unventilated?

Yes, a house built to 1930's standards, in the expectation that coal would be forever cheap, and occupants would wear jumpers and jackets indoors, is moving towards the 1960's.

I daresay the loft will be insulated as well. And the bathroom and kitchen provided with extractor fans. And the inside leaf of an insulated cavity wall will not be very cold.

I hope allex is already aware that he should open the upstairs windows in the mornings, and should not drape wet washing jndoors.