or maybe just try this url: http://www.ibstock.com/pdfs/technical-support/TIS-25-Laying-frogged-bricks.pdf
Rubbish! In 25 years on site I have seen literally hundreds and hundreds of thousands of bricks and indeed laid many a thousand myself, frog DOWN! In fact, I can't remember ever seeing them laid frog up........ The OFFICIAL answer from Hanson, who now 'own' London Brick and I quote: "London bricks should be laid frog up for maximum strength and weight: where neither is required as in most low-rise dwellings, bricks may be laid frog down." However, just to complicate matters, relatively recent sound insulation requirements (dense walls transmit less sound) might mean that we do have to lay frogged bricks uppermost. But still nothing to do with their strength or load bearing abilities in low rise domestic buildings.
I've never built a wall, but I've chopped out a hell of a lot of holes, and I'd have put money on the frogs being down. I'll take more notice now Yep, chopped a hole today in 17 year old house - frogs were down. i'm gonna keep looking
Good and bad practise has always been present in the building industry and this will continue to be so. While frog down may not threaten a problem, for say, two stories it may well threaten the walls under a more considerable loading, say four to six stories. Frog down is taking a shortcut, because bricklayers who tend to lay bricks in this way do it for speed. It is rare to see a bricklayer who lays frog down ensure that the frog is filled with mortar by placing the brick in position on the trowel. It takes longer than laying frog up. N. Green told us of some "old looking" frogged bricks that had high suction. Bricks should be thoroughly soaked before laying so that the moisture in the mortar is not absorbed by the bricks. Very rarely see this practise.
You do if you are laying Nottingham bricks. We used to leave the hosepipe running in the bloomin holes and they were still thirstier than us on a Friday night!
p.s. Goodwill. If Hanson say that frog down is good enough for two storey work then that is good enough for me. Also, having taken down hundreds of walls with frogs laid down when opening up houses for extensions etc. Never is the brick sitting on the outer 10mm of brick. The mortar always runs up into the frog at least half way. Frog down is neither a 'shortcut' or 'bad practice' (on two storey work) and I still challenge anyone who can say that out of the millions laid frog down, that they know of any failures on two storey work.............