I have just got a quote for a new roof as the existing roof tiles are not
longer made (Belgium made tiles made in 1928 and are of unusual design) I
think they are called Contre. The roofing firm has quoted for a breathable
under felt which does away with the need for venation I have heard of
breathable felts on wood framed houses, but not used on roofs, I take it
that building regulations cover this?

MikeS