Three More Roof Sheets Up

An Eccentric Anomaly: Ed Davies's Blog

Since my last post I've got three more roof sheets up but not, unfortunately, one at the top of the roof. That doesn't sound a lot for a bit over a fortnight but the weather hasn't cooperated (being mostly windy) and I've made some progress on refining sheet-lifting techniques.

First off, my previous post ended with the problems with the “batten-under” technique I'd been using to lift sheets with the thought of using some angle aluminium. I decided not to try that because of the risk of scratching the sheet below in the process. Remember the flimsy joist hangers I bought just in case? I chopped the ears off one

And nailed them to a short bit of batten with the holes on the end (with screws in here) on 6" centres.

This can then be screwed under the roof sheets using the required-anyway pilot holes and two stitching screws. This is shorter than the batten I was using before so doesn't foul on the neighbouring sheets. More importantly, the batten is offset from the holes so the sheet can lie flat properly once it's in place making positioning the bottom and putting the initial few screws in less inaccurate.

There are two sorts of screws I'm using for this roof: longer ones going through the ridges of the roof sheets into the timber battens and short stitching screws to hold sheets tightly together where they overlap not over battens.

First of the second row of sheets going up, sliding on timber battens to try to avoid scratching.

With a clamp on the batten next to it to hold it lined up nicely.

Screwed in place.

But there were a lot of hassles with that scheme mostly from the block underneath for lifting catching on various bits of the “transporter/erector vehicle” and so on. Accordingly, I made up a ramp for the middle and upper sheets to be slid up on.

It also makes protecting the sheets while climbing up on the scaffold tower bits easy.

The cross pieces are positioned to fall on or close where the roof sheets are screwed to the roof battens. Bottom end marked to show it goes to ground to achieve that (also extra cross pieces added close to the top and bottom).

Second middle-row roof sheet going up the ramp.

That worked well except that the batten still fouled on various obstructions because the way I'd put the rope round it meant it twisted away from the sheet it was screwed to. For the future I'll put the rope round the other way.

Still, up and screwed in place.

I also made up a short piece of ramp to hook on to the top part of the roof while lifting the top sheets. Here being fit checked near the bottom. It was made from the the last piece of batten I had left which had been rejected previously for serious use because it was so wonky and had, instead, been used as a support while painting the boards for the gable ends.

Yesterday I tried to put up the first of the top row of sheets. It got this far but no further.

The problem was that the top edge of the sheet sagged just enough that it snagged on the bottom of the top bit of ramp.

The obvious thing to do would be to chamfer the bottom ends of the ramp but the ends of the roof sheets are sufficiently sharp that they'd dig in if it was just plain wood. Putting some steel there would risk scratching the edges of the sheets. Hmmm…need something harder than wood but softer than steel. Stop and drink some Coke while thinking about it. Coke from a squishy aluminium can. Ah, a plan begins to form… First, take can home and wash out.

Anyway, I'd been thinking for a few days about how to lift the top sheets without running out of travel on my Prusik knot setup. I had various complicated schemes in mind then thought of the obvious one, two separate ropes all the way to the attachment point on the roof sheet as the block I have up on the top has two pulley wheels. Lifting is just a matter of alternating pulling, tightening and moving the knots. And, while they're both reasonably tight there's a degree of redundancy.

I had a trip to Inverness on Monday to get various things but failed to get more 12mm poly rope for this but the 10mm or whatever I have seems to work OK. Not using it for my safety rope, though.

Close up of one of the knot setups. Top left to bottom right: alpine butterfly knot in the white/green 6mm polyester rope, three half hitches in the doubled white rope, Prusik knot in the white rope round the blue 12mm poly. Confusingly in this picture the tails of the white rope out of the half hitches happens to lie behind the Prusik knot but actually aren't part of it. Ideally the doubled white rope would be a bit longer to make it practical to move the Prusik knot in longer steps.

Wet today, windy tomorrow but it should be OK over the weekend and for the first few days of next week to get this top sheet and a few more up.