cavity size

[JackofAll]

Will be starting the blockwork in a week or so and am wondering for full fill(300mm) how much bigger should the cavity be to allow for deviation in blocks?

[Canski]

Most blocks these days are 95 mm not 100mm It all depends on what you are using

 

[JackofAll]

53 minutes ago, Canski said:

Most blocks these days are 95 mm not 100mm It all depends on what you are using

 

Thanks for replying,I would've thought +-5mm, so do you reckon 305mm would do?

[Canski]

 

2 hours ago, JackofAll said:

Thanks for replying,I would've thought +-5mm, so do you reckon 305mm would do?

Yes plenty I would have thought but what blocks are you using ?

[JackofAll]

53 minutes ago, Canski said:

 

Yes plenty I would have thought but what blocks are you using ?

4 inch

[JackofAll]

5 hours ago, JackofAll said:

4 inch

In old money, 215x440x100. Was thinking, by building the cavity wider than the insulation and having weep vents would I be introducing air movement into the cavity thus decreasing the performance of the insulation 

Edited August 15, 2023 by JackofAll

[Iceverge]

I would just build it at 500mm external dimensions. 

 

The batts will have plenty of flexibility anyway .