Mixed use lobby ventilation

[Revol]

Did they drop a clanger [another one] in the gudinace for small single stair residential buildings with mixed use?

AD-B, Vol 1 2019, paragraph 3.28 d. states that for a small single stair resi building [not more than 3 stories above ground etc.] if the stair also serves offices or ancillary accommodation it should be provided with a protected lobby and a 0.4m2 permanent vent.

It the later gives guidance on flats in mixed use buildings in paragraph 3.76, again for small single stair buildings [not more than 3 stories above ground etc]. In this case the stairs can serve both uses as long as a protected lobby is provided - but no vent.