repair or replace?

[JohnD]

I have a 3-storey house, roof is asbestos cement synthetic black slates, about 18" x 10". I have a few slipped, quite a few on the weather side lifted by wind and moved, and wet verge mostly fallen out. I think house was built about 1980. Apart from the weather edge, slates mostly look OK and are bronze head and centre nailed. Probably the whole of the front and back courses will have to be lifted to renew the cloak and verge. Old verge is sand and cement mortar, has been repaired several times, mostly fallen out. He says new readimix will last longer.

Local roofer has measured up to price a repair, he tried suggesting that with the cost of scaffold it might be a good idea to reroof rather than repair.

Is that likely?

 

[colind86]

We really need pictures on this one. Cant understand why a fibre cement slate would be head nailed.

 

[alan333]

We really need pictures on this one. Cant understand why a fibre cement slate would be head nailed.

I've used similar/the same slates. They come pre-holed with nail fixing points each side about a third of the way down and are nailed to tile battens. However they also have a third hole at the bottom in the middle. You slide a copper "rivet" (thin head about 20mm diameter and with a thin shank about 20mm long) upside down between the gap on the lower course of slates, and put the shank through the bottom hole of the upper tile, and bend the shank over the face of the tile. It's to prevent the slates chattering in the wind.

Edit...maybe my memory isn't 100% on the position of the fixing hole points, and I forgot that the nail fixings needed to be copper too. Anyway here's a link to the modern (asbestos free) version, complete with a pdf on fixing them.

http://www.marleyeternit.co.uk/Roofing/Slates/Thrutone-Fibre-Cement-Slate.aspx

 

[colind86]

Ah right so its eternits/thrutones? I didn't know they done 450x250s.

 

[catlad]

Replace them they are a poor mans slate and I would expect they have had there life by now.

 

[JohnD]

if it helps, I am in a coastal location, and have had a number of slates come off in rare ferocious storms. The replacement ones had additional copper or bronze nails used, hooked over to hold them down, and have lasted well.