When I needed to know about how to fix these, I typed the subject into
Google groups and arrived here and found a good number of helpful old
posts and answers to my new questions - thanks to all. I thought I'd
feed back the results for the next person who does the same thing.
I needed to put a Velux on the side of a roof valley on the house, so
as to be able to do easy maintenance myself. I bought a Velux 140*78
with a flashing kit, and the total cost was around £280UK, I think. It
took all of a perfect May day to do, between me and son.
We worked from the inside. The early 20th century roof is made of
tiles nailed to horizontal boards on top of vertical joists, built to
last! I drilled holes through a board with one of those spade type
wood drills, and joined them up with a jigsaw. The boards were a good
inch thick, more than I expected. I used a power saw - the
reciprocating type - to cut through a joist, in order to pull in the
cut piece of board and make a pilot hole. Then we lifted as many tiles
as we could reach, and put them inside the loft. Once we could get
outside and stand in the valley, we took off the rest of the tiles,
and pulled the nails, then cut the hole etc as per instructions.
The Velux instruction books are comprehensive, but have no words, so
you need to have rehearsed putting it all together somewhere
downstairs first. We separated the frame from the sash, and lifted the
frame - which wouldn't go up through the trap - with a rope up the
outside. The sash with glass is heavy, and though I thought of taking
the glass out, in the end lifted it complete up the inside with a
chain hoist originally bought for moving a Rover v8 engine.
There are two instruction books, one for the window and one for the
flashing. Unfortunately they sort of interleave, and you have to move
from one to the other and back again as you work, which caused the
only real error of the day as we missed out a piece of metalwork, and
had to unscrew some bits to put it on.
In the book, there's a nice picture of a chap putting the sash back in
on his own. Not a chance! It's heavy, and althought the pop out studs
which lock the parts together are very clever, the little arms they
are on are a pig to get back in the grooves, as they wobble. Also you
need to do this twice whilst setting up, once to make sure everything
is square, then again at the end. It's not fun.
I'd never done tiling before, and I'd bought some fat headed nails
from Wicks, which meant we had to stop and go back there to buy small
headed galvanised 40mm nails, which are the right ones. Hanging the
tiles back wasn't difficult, just tedious. I managed to nail tiles
down the sides of the window to partially overlap the flashing, but
just slid the ones closest to the window under the others, where they
stay by friction - so far anyway.
At the end we felt we'd done quite a professional job, and the next
day it tipped down, so I had the satisfaction of looking out of my new
window with no leaks at all!