You dont say what type of door you have. If it is UPVC it may not be insulated, if its wood it could be too thin to benefit from any insulation values.
I suggest you re-seal the door and frame externally ensuring a good weather seal. Use any one from several types and brands available on the market.
This in itself does not guarantee it will solve your inside condensation problem.
With good external seals the next best option is to add a portable domestic dehumidifier, cost about (£25-30) are not expensive to run to reduce air moisture content... (due mainly to bathrooms and kitchens). This can substantially reduce house moisture without drawing any heat out of you hom, like extraction fans, it will reduce mold and provide a healthier environment for your family.
stan peachment, September 2010
