Weep holes needed?

[Tommy-Lee Staples]

I am planning to build a detached outbuilding with partial filled cavity walls and blocks on the inner and outer skin. The external blocks will be rendered after. I have read a lot about weep holes but they only seems to be mentioned on cavity walls with brick on the outer skin, which are exposed (not covered by render).

Am I right to assume that block external walls which are covered in render will not need weep holes?

 

[23vc]

Subjective depending on building control opinion last time I came across this. The logic being if it’s rendered it’s more waterproof so less likely to need them. Also depends on what purpose the cavity tray is serving

 

[conny]

If you have a DPC, (which you naturally should do), then the rendering can't go down to ground level without bridging the DPC.
When people talk of weep holes, most imagine a small round tube. But you can now get slotted weep holes which nestle between the vertical mortar joints and are quite unobtrusive.