Air Brick calc??

[Alan Ambrose]

Does this calc sound right (as it sounds like a lot of air bricks):

 

 

If I'm using these air bricks which say they are 1,290 mm^2?

 

List No. 350 Square Hole Air Brick 215 x 65mm - Forterra

 

I'm only ventilating a few cm behind a brick plinth which doesn't do any structural support btw. Can I still use the floor area calc even though I'm not ventilating the floor area?

 

Would peeps use, say, some stainless mesh masticed behind? 

 

[Mr Punter]

So is this an insulated masonry cavity wall?

[G and J]

Do you want for looks? We've gone for weep holes, which are much less visible, even though there are lots of them, and vermin proof! (Uninsulated cavity between GF block skin round timber frame).