Hanging by a thread

The 2nd and 3rd Velux windows are now fitted.  Hurrah!

Fitting the 2 larger Veluxes was essentially the same process as the 1st smaller Velux.  However, i didn't have the luxury of having an existing opening (skylight) to work from, which meant that i had to go out onto the roof to strip back the slates.

The roof is quite steep, not quite as steep as this photo suggests, but steep enough that it was impossible to sit on without sliding down it.  So, as well as wearing a full body harness with a fall arresting inertia reel, i had to use a rope in which i tied foot loops.  So, whilst sort of sitting-laying on the roof with the sole of my foot in the loop i started stripping the slates where the Velux was to be fitted.

Once enough slates had been stripped i was able to cut through the sarking boards and felt to form an opening large enough for me to fit through.  This meant that i could strip the rest of the slates and form the full opening from the relative safety of the loft.  Forming the full opening was covered in my previous post, so no need to bore you with that again.

As before, the sash was removed and the frame was fitted into the opening with a 20mm clearance all round as per the instructions.

The Velux is secured in place by these large brackets which are screwed onto the frame before fitting then screwed through the sarking into the doubled up rafters.

Felt is fitted up against the frame and i have also sealed this onto the frame using roof sealant.  This isn't strictly necessary, but i wanted to reduce the risk of leaks at the rear elevation windows in particular as it's less sheltered than the front and exposed to high winds and driving rain.

The flashing kit is has to be ordered over and above the main Velux window and it's an extra £60, but it's well worth it as each part fits accurately, providing a good weathproof seal.  The kit comes in 4 main parts, top, bottom and two sides.  The top and bottom flashings are large single piece, shaped metal sheets which are fitted to the Velux frame and then slated over, with the bottom flashing creating a 6 inch apron for weathproofing.  The side kits come in 7 pieces per side and each one overlaps the other with the 'tangs' folded down to hold it in place.  A capping piece is then fitted up the edge of the frame and this capping piece covers the upstand edge of the flashing pieces.

There appears to be two ways to fit the flashings, one is the way i've done it and the other is to overlap each individual side flashing with a slate.  i.e. alternate flashing, slate, flashing, slate.  I preferred to fit the flashing as one piece before slating it in as i believe this gives a better seal to the roof felt and reduces the chance of wind driven leaks. The slates on the rear elevation of the roof are easily twice the thickness of modern slates and overlapping them with the individual flashing pieces would have meant they would have sat higher than the edge, which would have made fitting the capping piece almost impossible.

 

And here are the two rear Veluxes fitted and slated in place.  So far there's been a few good days of heavy rain and no leaks, so it looks like the job's been done well.

I'll be back out on the roof in a while to fit the slate vents, so i'll be keeping my harness, inertia reel and rope handy, because falling 30 feet might sting a bit and may leave a nasty bruise!