The build

Impressive SC, when you said you'd bought a sawmill, that wasn't what came to my mind. I can understand your enthusiasm,  a step forward for self sufficiency.  How do you know how much cladding you need and whether you have enough wood?

I hate to use bad language but it’s………………..mathematics     .

you work out your surface area. Then you can work out how many boards you need.  Because you already know how wide they are and how much of an overlap is needed. Then the tricky bit is working out how many boards you’ll get out of a log. You can have a fairly good guesstimate. 
All perfectly simple    .

we got 22 boards at 4m long out of our first log.