Tim,
Originally I was actually looking at using 14x12 BBs like you. I then drifted towards the idea of using commercial BBs with national supers. Then after discovering the concept of a OSB system I found myself considering using all standard national BBs, rather than the random size of Rose boxes & frames only provided by Thorne, and nobody else uses them so slotting locally provided nucs would be a pain (even though the national BBs would certainly be heavier!).
I thought the OSB idea would simplifying my purchasing and beekeeping as all boxes can be used in all positions, rather than having spare supers and needing to buy more BBs or vice versa.
So... where am I now?! Hmmm... currently thinking stick with national BBs, use a double brood if required, and then national supers for stores.
OR
Use 14x12 BBs and national supers.
Both of which can be purchased as budget British Cedar (commercial BBs not available in budget format).
But I do like the sound of the OSB approach, but it might not be relevant until I know how good my (very green) area of Somerset is for building up colonies... they might never require more than a single brood box anyway... I haven't gone round surveying the local flora with a clip board yet! But we have a lot of pasture, a lot of ancient hedgerows, and gradually more and more miscanthus (but not sure if that flowers in a bee friendly way). Sadly Somerset lost 50% of it's orchards over the past 50 years (although Thatchers are doing a lot to change that having planted 50,000 young apple trees a couple of years ago... so that puts them up to about 400+ acres of orchards... I'll see if google maps tells me how far away as the bee flies!
I'm rambling!
And just noticed there is a massive post above that I haven't read yet!
Thanks pargyle!... I'll get reading and comment accordingly!
B