Fixing loglap cladding to timber frame ? one or two !

[grahamdvd]

Hi I will be starting to fix the 18mm thick loglap to the exterior of my 4 x 2 frame. I do not have a nail gun, so was going to screw the loglap on, I have lots of drill/drivers !
The loglap is 100mm wide, do i put one or two screws on each fixing ? I have got some 4 x 50mm stainless steel screws, I read somewhere only one screw in each fixing due to expansion but on another post it said two screws ? thanks

 

[foxhole]

Will look ugly and liable to split with screws, get the hammer out.

 

[grahamdvd]

I was going to pre drill the screw holes ? I would have thought nails would be more prone to splitting ?