I live in a 1960s semi and we have always had loads of condensation on
the windows, worst in the winter.  We replaced the old aluminium
windows / doors with UPVC and while this has improved slightly we still
get misted up with puddles on the sills.  Therefore, there must be
another cause.  We have a de-humidifier that reduces some of the
condensation but it can only be in one room at a time. 

Any ideas what could be causing this and how we can resolve it?  Could
it be anything to do with the damp proof course?

Thanks.


-- 
Gareth Haynes