Two Roof Sheets Up

An Eccentric Anomaly: Ed Davies's Blog

Today I put up the first two roof sheets. Some lessons were learned.

Thursday, when I finished off and published the previous blog post was too breezy for doing anything on the roof so I just cut the grass at home. Friday was forecast to be calmer but by the morning the forecast had changed to the wind dropping in the afternoon. In principle I could have done a few jobs on the house but I didn't really have the energy and anyway the wind didn't drop till quite late.

Saturday was perfect. Cool air, bright sunshine with just a light breeze. The first job was putting the insect mesh, firestop and DPC on the top half of the north-roof verge to the east gable and also to tie a pulley to the top batten of that roof.

Then I added a temporary ramp to access my area of temporary decking in the porch/greenhouse. Remember the “field expedient” crane I used to lift the purlins? One of the bits of wood for that had be lying outside since and looked pretty scruffy on the outside but when I cut it in three the inside still appeared to be in perfect condition:

Those and another offcut now form a ramp:

Next job was assembling a roofing-sheet “transporter/erector vehicle”. Ingredients: sack cart, 3m of scaffold tower, three bits of batten, numerous tie wraps:

With roof sheet on ready to have pilot holes drilled:

By the time I'd done that it was too late on Saturday to try putting the sheet up.

Sunday was forecast to get wet and windy in the middle of the afternoon. I went up to the site about 11 o'clock and tried lifting the sheet on to the roof with a bent coat hanger into two of the pilot holes.

That gave way pretty quickly so the sheet only dropped about 50mm. By that time the breeze was beginning to pick up and showers were visible across the valley so I packed up with the rain arriving just as I left site at 12:40.

Today was another perfect day so I tried a slightly different tactic: putting two screws through the sheet into a batten underneath and tying the rope to that.

Up and with enough screws to make it secure. The difficult bit was getting it squared off properly - it's out a bit so there will need to be a few adjustments further along the roof which won't be ideal aesthetically but will be fine functionally.

I lifted the sheet with a length of 6mm polyester braid-on-braid rope. Of all the various ropes I have lying around this is the least likely to snag on anything. To be able to adjust the position at which the sheet hung easily I used a Prusik knot on some blue 12mm polypropylene rope I've also been using as a safety rope while working higher up on the roof. Because the polyester is so smooth it doesn't grip all that well so there's a random bit of white rope in between. (Yep, tried with a climbing harness, those white and blue ropes and a Prusik knot and they take my weight easily.)

Second sheet got out of the house, pilot holes drilled and starting to lift:

But then one of those doh! moments. The batten screwed underneath for lifting was too long - it extended into the area where the two sheets overlap (I'm overlapping them by two ridges which I think is a one more than commonly done but the rain velocity around here does tend to have large horizontal components).

I tried to get in with my multitool to trim it down in place but, being careful not to scratch the coating on the underside of the steel sheet, found that too difficult so bought the sheet back down on the TEV and cut it there with the circular saw.

And then up.

Plan A was to put the screws on every ridge for the sheets at the ends, next to the gables, then every other ridge for all the rest of the sheets. However, I got a bit carried away drilling the pilot holes for this second sheet so Plan B is every ridge for the two columns of sheets at each end of the roof.

So done on the roof for the day, I drilled the pilot holes in the sheet to go above the end one here. The general idea is to start with the down-prevailing-wind end of the roof and, before adding a higher sheet, to already have the sheets below it directly and on each side so that they overlap nicely.

Having done those pilot holes and shut up the house I was putting the last bits in the container when I noticed the pack of foam strips which are to go top and bottom to keep out creepy crawlies. So, bottom row of screws off, feed those in, screws back in.

I'm having a rethink about how to do the lifting. The batten underneath scheme doesn't work that well partly because of the clash with the neighbouring sheet as found above but also because it sits over the batten the pilot holes it's using are intended for making it harder to line the sheets up.

Tomorrow I'll try with the batten on top of the sheet. However, that's not a general solution as it won't work with the top sheets as they necessarily have to go over the pulley. More thinking required, perhaps involving some angle aluminium. In general, this current scheme works well enough but needs to be streamlined if I'm to get the roof done this year.