Block wall footing on sloped slab.

[Jake.]

One thing i just cant get my head around is how to make a level footing base on a sloping slab. The slab will be 4m wide & a 1 in 10 slope i guess will be a 40mm slope. (for water run off)

Now can a blocklayer start a 2.6m wall on that slope leveling the first block with the mortar ?

In the engineering drawings the base of the wall has a raised bit im assuming is for providing a level base to start the blocks.

Do people do this & if so how ?

Cheers.

[Blocklayer]

Now can a blocklayer start a 2.6m wall on that slope leveling the first block with the mortar ?

1 in 10 over 4m = about 400mm, not 40mm.
But even at 40mm, yes, he could, but don't do it. If the first course isn't pretty much spot on, the whole wall(s) will end up out of wack. 50mm of bed joint (40 drop + 10 bed) is too much to 'bog up'. You'd most likely end up with a wonky (out of plumb) first course, and still be 20mm low one end, and trying to lift gage one end and probably tighten down the other will throw openings out of level/plumb and the wall ends/corners are hard to plumb if the blocks aren't layed level.
I'd cut the first course. Its only 4m long, so (at 40mm) you'd get away with probaly 7 or 8 cuts. Start the low end with a big bed and you'll lay 2 or 3 (up hill) before you need to cut. The wall at the high end of the slab will end up a bit lower than 2.6 (maybe about 2580-90 if you get up a bit).
At the end of the day (job) cutting the first course level will be well worth the trouble saved trying to bog it up.
40mm is not hard to work out the cuts, but for steeper angles, try this block cutting calculator http://www.blocklayer.com/Raker.aspx

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[Jake.]

Your right, anyway 40-50mm is all i will need if that.

One thing i didn't make clear is that the sloping slab is to go sideways from the wall. The wall length is 23m & this will be level just a gentle slope away from the wall sideways.

Thinking about it maybe i could do with less a slope as to not effect the block footing as much.

Edit - looking at your above quote i should of said "the first row of blocks"

[Planned LScape]

We had this drama during the week.

An area of paving 50m² on a conc slab base with about 85mm fall along the length and a retaining wall along the side of it had to be level.

We started the wall at the lower end, with the bottom of the first block just below paving height, and when it ran into the foundation level for the wall we had to cut the blocks so the 1st course was all level. Then if there is enough rise in the paving you can step it up to the 2nd course directly.

If the 1st course is done right, the others will be easy. It determines both the quality and the ease of the job