We have an old stone cottage, not listed but in a conservation area. We need to replace rotting windows - caused largely by condensation on the inside. Any tips to prevent mould/pools of water on the sill/further deterioration in the new windows? The panes need to be level with the outside of the house for planning reasons (i.e. leaving the 2-ft thick stone sills all on the inside). I would happily settle for UPVC so I never have to get them painted again, but the planners may not agree.