zincalume roofing screws question

[gg23]

hi all,
Glad to report have just passed structural inspection!!! phew......


Getting ready to clad roof and will be using roofing blanket and zincalume. I am told that the roofing blanket is 55mm thick. I was intending on using 14-10 x 65mm self drilling Buildex Type 17 hexagon head Screws with seal but am concerned about how much the screw will go into the trusses. The suppliers of the roofing material tell me that they usually use 50mm screws with a blanket so does this mean that the blanket can be compressed?

thanks
greg

[chrisp]

Yep.

[journeyman Mick]

.........but am concerned about how much the screw will go into the trusses...........

I hope you mean batten or purlin rather than trusses.

Mick

[Make it work]

Is the roofing corry or trimdek (square lock) profile? The reason I ask is they have a different profile height and so need different length screws.

If it is corry, 12-11x50 type 17 hygrip screws are perfect, even with blanket. If you have trimdek or equiv. then 12-11x65 is the one to use.

Also, unless you have an unusual requirement, you don't need to spend the extra (lots) for 14g screws, 12g is fine for non cyclonic areas, they are cheaper and easier to use.