Slate hook length

[aa44]

I am about to put the slates on my new garage, using stainless steel pointed end slate hooks.

Can anybody answer a question for me on the right length of slate hook to go for? The slates are 400x250 "Scottish Heavies" which are about 8mm thick. The headlap will be 96mm (with a 152mm gauge). I have mocked up a bit of the roof and the 100mm slate hooks that I have seem a bit of a tight fit. I have to put the point of the slate hook in immediately above the slate below (no gap at all). As a result, I can't drive the hook all the way in (because of the thickness of the slate).

Would I be better off going for a 110mm slate hook?

Thanks
AA

 

[Alastairreid]

Is it ballachulish slate?
Why are you using slate hooks? head nail and stitching is the way to go.

http://www.historic-scotland.gov.uk/informguide-slate.pdf

 

[aa44]

Hi Alastair,

The slates are Spanish 400 x 250 and are holed about 110 mm down the slate about 30mm in on both sides. Because it is very windy where we are building, I am going to nail them (using the holes provided) and use slate hooks.

AA

 

[SurreyRoofingEstimator]

Blimey, they're not going to go ANYWHERE when you do that! lol

You should though only need to hook fix really. Didn't even realise that the Spanish quarries produced 8mm slates (mind you, no call for them darn sarf)

 

[aa44]

They don't seem to produce a lot of thick ones! The slates that I am using are from SIG and, of their whole range, only one lot are thick. They seem to be being used on all the new slate rooves in Shetland!

The plan is that the slates aren't going to move!