Sheet roofing fixings

Ok, I now have my 14 sheets of Onduline corrugated roofing ready to fix in place. I didn't end up getting a price match from Wickes because they demand a receipt from another shed for identical material, B & Q do Coroline, not Onduline and Fred the Outside Shed man at the local B & Q seemed to only exist as a telephone contact for the other staff rather than someone with whom to press the flesh.

So Wickes it was. I am certain I need to screw the roofing on over the existing felt rather than use nails. The screw plus washer packs in Wickes have 55mm screws which is too short for Onduline, and don't sell the capped washers separately. I've searched online at B&Q and Screwfix, but can't locate suitable capped washers. There seem to be some things called Selawashers advertised on the 'net, but is there a more generic name for these things? I suppose I could use penny washers and gunge, but something squishy would be better, I think. I'm going to need about 300 and I really prefer to be able to see and feel the goods rather than mail order.

Why is everything so difficult? I suppose it must be me.

Reply to
Bill
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If you're going into solid wood you can use these by pre-drilling the top of the corrugations:

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nails would also be much cheaper than the screws + caps from Wickes as the quantity you want (about 300) would cost about £70-00.

I doubt if you really do need 300 fixings for 14 sheets. I've just fitted a new shed roof (metal corrugated with transparent plastic inserts for light) and I used just 6 fixings per sheet. If you can use fewer fixings it might be worth buying the screw packs from Wickes and then buy longer screws from Screwfix.

Cic.

Reply to
Cicero

In message , Cicero writes

Thanks for that. I really don't want to use nails because of the way I have things + insulation attached to the underneath of the roof, and the way it gives me a gut feeling that hammering into it might not be a good idea.

The screw packs plus new screws is a possibility and I suppose I can always use a load of 55mm screws in the future.

I have done a tour of local roofing and decking suppliers this morning and ended up somewhere that suggested 30mm dia "Dowty" washers, which did look like a possibility. They also had screw covers (plastic washers with a hinged cover) in "large" 15mm dia in a dark brown colour. I think these might just about be OK as long as the full sun doesn't cause plastic degradation over the 15+ year life..

The spec calls for 20 to 25 fixings per sheet and my roof angle is only just within the 20 range. A largish area of felt was ripped away in the gales and at my age I need a lasting, solid and easy job, so I've been thinking of following the instructions (ish). .

Reply to
Bill

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I can understand your reluctance to avoid nails so a few comments on screwed fixings. The plastic cups and caps are not entirely satisfactory in my opinion. The caps (even indoors) tend to fall out and would leak on a roof. The 'Dowty' washers could be your best bet as they're designed for farm buildings as far as I know.

An alternative might be to make your own washers from offcuts of lead flashing. Square washers (about 1.5" square) were once the standard fixing washer for corrugated roofing sheets, and would be easy to cut and drill. A smaller reinforcing washer under each screw would make a strong job.

Cic.

Reply to
Cicero

I used ~140 nails in 6 sheets, following the instructions. It won't go up proportionally as the edges take a lot, but these flexiple sheets do need a lot and shouldn't have more than 100mm overhang past the edging nails.

Reply to
PeterC

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I'm really surprised that they should require so many screws, but I suppose the flexibility is the reason. It does seem to make a reasonably priced job an expensive job when you're spending nearly £35-00 for not many fixings. I actually handled the sheets a few days ago in Wickes and felt that they were less rigid than I'd previously believed.

Cic.

Reply to
Cicero

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