GB ITS ALL RUBBISH!ive had loads of so called "breathable" waterproof jackets!and ive never found one that doesnt make you sweat a lot and most dont keep you dry from the rain either! :

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do i work in heavy rain?i have done on occasions if im half way round a house and i just want to get done and get home.usually if its heavy ill shelter in the van or a customers kitchen (with a brew!)and then crack on when it eases!
if its domestics then i sack it off if its persistently heavy(esp if windy as well!).ive worked in blizzards/gales/rain/sleet/snow if its commercial work im cleaning though!!
domestic custies(mine anyway!)i usually ok with me working in the rain even heavy rain from time to time but if their the big posh country houses that are well priced i tend to wait until it eases off a bit.