Patio step and air bricks

What on earth is an "ACO"?

You could extent the ventilation using vitrified clay pipes or even plastic ones.

 

I assume the OP means a channel drain of which Aco is a well known brand.

 

As suggested, extend the vent. Plastic air bricks and rectangular ducting is available

 

Oh. Not an Anglican Communion Office then? Thgought it might be a bit ambitious, what with the Archbish of C attending, etc. How mundane (the word "drain" would have been a good thing to include).

 

I'm curious how the channel drain works, do you just cut the slabs and drop it in?

 

We generally refer to channel drains as Aco, just as all vacuum cleaners are hoovers and all front loader/backhoes are JCBs.

 

Keep top of step 75mm below sill.
Remove air bricks.
Insert two of these ducts, side by side. https://www.toolstation.com/100-flat-channel/p39632
Brick up remainder & seal around ducts ensuring at least 8 square inches or more free flow into ducts.
Terminate with one of these which has 13 square inch free flow. https://www.toolstation.com/9-x-3-a...L7j0tQ3iwSllNHXMojQaAsHcEALw_wcB&gclsrc=aw.ds

 

"We"? You mean "you". "ACO" or even "Acco" + drain is easy enough for people to type.

 

By "we" I mean peeps who know what they are talking about, including the OP in this instance (and of course Gadgetman & Arrow)

Pedantry belongs on the sparkies forum: they love it there.