Thread: Timber grading

MGP10 is about the equivalent of F7.25 if that makes any sense. It is slightly above F7, but not close to F8' which is the nearest F grade to MGP12.

Similarly MGP12 is slightly stronger then F8.

This of course is theoretical, being based on destructive testing of boards that make MGP grade against boards that make F grade... By which I mean that both boards would be at the limit of strength reducing characteristics that could actually make that grade.

IN PRACTICE... As against theory... There is a significant margin applied to F grading of around about 30% or so. Add to that safety margin that most graders will, if in doubt, downgrade a board. (As a grader you don't get hammered except on price by knocking a board down a grade but you will have all sorts of strife if your timber grades lower then you've indicated)
what this means is that it is highly likely that F7 graded timber while theoretically slightly weaker then MGP10 will meet or exceed it in practice.

in the real world the difference is that minor in any case that it's moot. If you're that concerned just specify F8.

Well, in my real world, there is no such thing as F8 or MGP12 in H3,I wish there was.
In fact i had to go to 3 different suppliers to even find MGP10 in H3. I found it in Bunnings of all places. When I asked the timber guy if they had MPG10 he said neeee, we use to have F7 but now have only F5. Yet knowing Bunnings I checked the timber and it was all MGP10 H3 perfectly straight and very clear of knots.

They even cut the 6m length in half for me, something they use to refuse not long ago for OH&S reasons... allegedly.