Fixing corrugated sheeting on a roof that does not have exact 90 degree corners

Calahonda52

critical piece is the 3" over hang to gutter

shed 10 meters long, 10 sheets, 2.4 long

Any thoughts on how to get the 3 " line correct

Thanks as always

The Continental Op

Bit of a bodge but you can make corrugated sheets wider by screwing down tighter. In fact over tightening the screws can mess up the lay of the sheets across the roof so what looked a perfect fit won't be after a few sheets are down.

For the corners I think I'd fit the sheets making the best of any squareness you have leaving the smallest space for the corners. If you can have it so the corner sheets are less than one sheet then one sheet cut might do two ends. If you can have the "square" sheets to within a couple of corrugations then that would be ideal. Then at the ends lap the cut sheets an extra corrugation under the main square sections for strength and water tightness.

I'd always try and put any cuts in main sheets at the top so the bottom edge looks nice and clean so if possible I'd get the overhang for the gutter correct then cut to fit to the ridge.

Is the line along the gutter straight? You can put a string line up to get the overhang right or use a piece of timber as a gauge if the wall is straight. If its a one man job clamp the timber under the bottom of the sheet and slide it up till it stops then screw down.

Mr321

As above get the gutter sides overhang and straightness best you can. The 6inch ridge flashing will give a good bit to play with that if it's off it'll be covered up. Then I'd imagine your putting side 90 degree flashing on the to ends where it's off so that'll also help

the_pen_turner

how far off 90 are they

what iv done several times is put on the first sheet with the overhang. 1 screw top and bottom. then sticher on the next 5 or 6 sheets but no to the timbers. then lift up the middle at the ridge a foot or 2 so the top distance gets narrower . then screw the last sheet down to the correct overhang. fix in the middle at the bottom to a line and then push down the hump at the top. put a timber on top to help even out the push if needed. then screw it all down.

its amazing how much you can gain or lose by doing this.

Calahonda52

Thanks, interesting ideas here, so clamp a sheet in a bit from the end and another half way onto a 3" wild w.8m long stick and another in a bit from the other end ..

Thanks PT, ur ideas came in after I posted

monseiur

Step one - measure from ridge board to fascia board at both gables & centre of shed - all three measurements should be more or less equal

Step two - select a rafter that will not be covered when you lay down the first sheet - probably the second or third depending on spacing, check that it is at right angles to ridge board / fascia board - a simple way to do this is the 3 - 4 - 5 method. If rafter is OK lay down first sheet using the rafter as a guide, the space at top & bottom between inside edge of sheet and rafter should match.

As your wall is off square the first sheet will overhang at either top or bottom. You will have to trim off this overhang before fitting barge cladding. The trimmed piece should look like a long triangle - starting at nothing and gradually widening to max overhang.

Once you get the first sheet right (including correct overhang at gutter) the rest will be fine - as you lap them the corrugation will keep them 'true'

It's much easier & simpler to do on site than trying to explain it😊 The whole idea is to have sheets at right angles to fascia board to ensure an equal overhang at gutter along the full length of roof.

Calahonda52

am going at it this afternoon so will keep you posted