With the roof fully stripped, we discovered a purlin running right behind the original skylight at the top of the stairs (which we couldn't see before because it was behind plaster). This meant that the larger replacement Velux window could not be accommodated. As this is a smoke vent window and part of our fire safety design, this was a significant issue. I phoned Velux customer support, and they helpfully suggested that two smaller windows and a separate control unit could be ordered (one window above the purlin and the other below), together performing as per the originally specified window.

Having taken up this suggestion, in order to avoid too many windows on the roof (for both aesthetic and structural reasons) I decided to change the two originally-specified windows in the front bedroom for one larger window.

In addition, the joiner had built the platform for the rainwater header tank whilst I was away at Redfield, and not done it exactly how I'd envisaged (serves me right for not providing a drawing!). However it will suffice, and the way he's done it means we can put the top floor bathroom MVHR underneath (rather than next to) the tank - still need to finalise the ductwork though.

All this was agreed verbally on-site with the builders over the space of an hour or two. Then I had a shock when I found out that the price of the two-window solution for smoke vent, as suggested by Velux, is significantly higher than the single window we were originally to use; this combined with the extra slates required has now pushed the roof works about £2k over-budget!

So I (re-)learnt the lesson: preparation is key, don't be making - or worse, changing - design decisions on the spot.

Meanwhile, we got a business card for yet another tradesperson claiming to do tree works - several phone calls and voicemail messages later, no call back.