Block outer leaf - 75mm as planned or 100mm as standard?

[G and J]

Late in the design process we twigged that lenders like masonry skins covering at least part of timber frame houses.  So we added one the ground floor, and we converted the garage to all 100mm blockwork with 200mm pillars.  

 

Ours is a narrow site so I've always striven for the thinnest walls possible, so I went for 75mm block rather than 100m.  The architect then added 25mm of render.

 

Fast forward to working with our SE on the foundation design and he commented that whilst 75mm would be OK he'd do 100mm himself. This would grow the walls a bit, but not by 25mm if we went over to one of these new fangled render systems like k-rend.

 

Views?

 

[Russell griffiths]

Yep 100mm and 8mm render and 1.6mm top coat. 
haven't seen anybody lay 75mm blocks for a long time. 
how bigs the cavity, if you use surecav can you tighten up the cavity a bit. 

Edited April 13 by Russell griffiths

[G and J]

1 hour ago, Russell griffiths said:

Yep 100mm and 8mm render and 1.6mm top coat. 
haven't seen anybody lay 75mm blocks for a long time. 
how bigs the cavity, if you use surecav can you tighten up the cavity a bit. 

Cavity is 50mm. I thought that we had to keep the cavity clear to allow the frame to breath.  
 

That render thickness sounds good.  Is that k-rend?

[Russell griffiths]

The cavity is clear if you use surecav, you can go lower width cavity if you use a proper barrier 

50mm is fairly standard to allow for inaccurate building practices and materials. 
 

ensure you keep the bottom of the cavity clean, you will need to exercise old fashioned good practices to keep the cavity clean at the bottom.