Window In

An Eccentric Anomaly: Ed Davies's Blog

After the previous attempt at installing the small window in the main bedroom resulted in a bit of a falling out there was a longish break for the weather but it's in now.

Most of the rest of January and the first bit of February had snow lying. Not a lot actually fell, it just lay for quite a while. A bit more fell at the beginning of February resulting in this view from the rented house on the morning of Saturday the second.

The local road was a bit tricky, it's pretty low on the council's list of priorities for clearing, but the rest, including up to the house site, were kept well cleared but it was slippery enough underfoot on site that I didn't want to even contemplate moving the window.

I'd not meant to hibernate this winter but when the snow cleared and the weather turned abnormally nice for the latitude and time of year I was still slow to get going again, not least because of a number of trivial ailments.

Anyway, I got the window out of the container and replaced the batten above the opening with a new one placed a few mm lower so that the screws would have a better grip. Here with the insulating collar in place.

Then I fitted the window frame and checked it for square with my laser.

Bottom left, horizontal beam just below the edge of the sill, vertical beam just inside the frame.

Bottom right.

Top left.

Seems reasonable.

There's an allowable range on the width of the window opening (820 to 840 mm for this size). I'd aimed for the middle but with the real thicknesses of the OSB (the rough surface making it effectively thicker than its nominal dimension) and other minor inaccuracies adding up it turned out to be only just above the lower end of the range. This means you have to remove one layer of the insulation from the collar (it's designed to be peeled off) which is fine but it does mean there's less sprong available to adjust the squareness of the frame so you need to get it closer to right in the first place. For the other windows I'll make the opening a bit wider.

This time, I used longer screws at the top.

Left to right: the screws Velux supply to go across the top, the ones they supply to go at the sides into the main roof structure once the frame's been squared and the type I used in the long slots at the top this time.

During the down time early in February I got a pair of 1000 kg lifting strops, one 2 metre and one 3 m. I used the 2 m one with one of my chain hoists to lift the sash into place.

From that point on I had my hands too full to take any more pictures. It was a bit awkward to angle the window to get it through the frame but at least it was all stable along the way so long as I kept a bit of weight down on the top of the sash (left in the picture) to counteract the heavier weight of the bottom part. It only took a few minutes from then until the sash was properly in place.

I was a bit disappointed by the squareness, though:

At least this time round it was closing properly but it was just about binding bottom right and top left with much wider gaps bottom left and top right. The approved Velux method of fixing this is to put a jemmy in and lever the frame to the right position. This sort of worked but didn't move it quite far enough and there wasn't any easy way to hold it in position while I went outside to tighten the screws up. So I left that to think about overnight.

What I did was to rest a scrap bit of I-beam up against the frame with a lifting strop and chain hoist hooked round a bit of threaded rod left over from when I moved the end brackets to the south and similar from the middle of the beam to the north.

That made it easy to apply steady pressure to the frame to push it into shape and tighten up the screws. Still not absolutely square but by this point I was applying quite a bit of force and didn't want to push my luck.

Since then I've been dabbing at getting bits ready to do the roof window in the south side of the small bedroom at the other end of the house. In retrospect I could probably have got that done in the recent run of good weather but I didn't know in advance it was going to last and I'd really prefer to be a bit further into the year before cutting holes in rafters and sarking boards.