I have a UPVc double glazed small extension off of my kitchen. Unfortunately it is not very well ventilated and has caused a large amount of mould/mildew on the mastic. Can I remove all the mastic and replace it with new antifungal mastic? If so, what's the best way to remove it?

Estelle, November 2010

Thanks and Good luck Estelle
A small electric extract window fan may help the situation

Maurice, November 2010

Thank you Maurice.

Estelle, November 2010

If the mastic is sound then just clean it with a bleach solution in warm water.

If it is pulling away then it can be removed using a metal scraper (but take care not to damage plastic window frames) or perhaps a cheese shaped wedge of hard wood.

Another way is to buy a mastic solvent (check small hidden area that solvent does not effect plasic) from DIY plumber merchant.
Once resealed, see if you can improve ventilation in this area or perhaps get a bit more heat into the room.

Maurice, November 2010