A smoke vent for buildings having no moving parts comprising an opening (13) or gap (13) in the roof and a secondary roof (16) spaced above and covering said opening and projecting over the roof adjacent the opening to prevent the ingress of rain or the like characterised in that at least part of the secondary roof (16) is clad with material which will burn when subjected to high temperatures without substantial disintegration into debris or molten particles. Preferred materials are acrylic or polycarbonate based plastic sheeting.
