Hi - I'm currently planning a renovation and extension to our 1960s semi. We want to put roof windows over the new rear extension on a fairly shallow pitch roof (probably about the minimum 15 degree pitch possible for tiles). As the house is a Wimpey chalet-style with rubbish insulation on the upstairs dormers, and the standard of the original brickwork, especially in the loft, makes it look as if installing cavity wall insulation may be problematic, I'm looking to do as much as possible elsewhere to bring it up to modern insulation standards during the work. I therefore want to get the windows right but do need to be very mindful of overall costs.

I've discovered a brand called Duratech, which a comment on another forum appears to say is in fact old stock previous generation Velux windows. Duratech is significantly cheaper than either Velux or Fakro. Does anyone out there have any experience of them, good or bad?