How much grade change are you looking at over the run of the wall? Is it pretty level, or are you stepping down and back up again?

Also, is your slab level, or is it pitching across the span of your walls?

The wall is intended to bring a planting area up level with the existing slab. At its lowest point, the ground is about 12" below the slab.

The slab itself does slope somewhat, mostly unintentionally (it has settled a whole bunch.......Im sure there was some slope originally designed but not as much as I see now). I didnt want to try and follow the grade of the slab, because my whole wall would be out of level.

I dont mind seeing a height difference between my wall and the slab (I started at the end of the wall you would see the most, making that exactly flush with the top of the slab). I really just want to make sure that the 2 "halves" that Ive started to create meet at least close to level. 1" is off is bad, 3/16" not so bad. I will be putting cap blocks on top of the wall, so I could make up for a little variance by using extra landscape adhesive/mortar to hold the caps on.

OK, I'm just your average back yard hack, but here's what I would do: I would start building this wall at the centre. Don't you need more layers of bricks out there anyway, making it more logical to start there?

You can establish the height out there from the centre of the slab: first run a line (or a straight 2x4 on edge) from the point at which you want perfect alignment to the spot on the slab that would be the centre point of your circle. If I understand correctly that's already lower than your wall level, so pile up a couple of bricks there to make the height you want (or mark it on the side of the slab if it's lower). Then establish your target level with a string (or 2x4) running from that centre point to the centre of the wall, AKA the radius of the circle.

Then you build from the centre to the ends, and do your brick-cutting and micro-levelling either at the slab or two or three bricks before. You can move your line as you work and keep re-measuring, to minimize the amount of correction you need to do.

KarinL

That might have been the way to go but I have already started :) and I have a whole bunch of the wall already laid, didnt want to undo it all and start over.

The reason I didnt start in the center is because I didnt know how many blocks I would need to curve from one end of the slab to the other, and have it line up close to each end. Thats why I started from each end and am working my way to center. In the center I expect to have to cut some blocks (unless by some chance it lines up perfectly), but that ensures that on each end its flush/level with the edges of the slab Im trying to meet up with.

Ok, so if I understand this correctly- since you're concerned about mating up the two sides, does this mean you are you digging the footer as you go?

Yes, thats exactly what Im doing.

Since I didnt have a reliable way of laying out the wall to dig the footer first, Im basically digging about 2 blocks at a time, tamping, filling with 2" of stone dust, tamping, dropping in a block and levelling it.

I realize now I probably could have laid out all the blocks in my garage up against a wall, then futzed with it until the diameter of the half circle was the 20.5' I need to go up against my pool slab, but of course hindsight is 20/20.

I just tried a water level and it shows me 1" off. Im going to redo the water level again, and see if I can repeat that measurement. Since I havent been able to repeat a string or laser level measurement, those data points are useless to me.

Only other option is to break down and rent a good builders level but the cost is kinda nuts (75 bux for 4 hours, Ill need it for about 30 minutes).

If you can get a nice straight piece of wood on edge, you can use that with a level on top of it.

Or wait till you get to a gap of about 6 blocks being as level as you can measure now, and then adjust them to meet. I wouldn't think that would show as too much of a kink in the end.

This does sound like one of those projects that takes you so far up the learning curve that after you're done, you've got it all figured out to the point that you hang out on landscaping forums advising others - I've had a few of those!!! :-)

KarinL

Thanks.

I thought about using wood somehow but since its such a large gap I wasnt sure. I suppose I could "mend" a few 8' 2x4s together and put a level across the top edge of them.

Now that I think of it the correct way would have been to put the blocks up against a wall (garage, foundation, etc) and figure out how many to curve, how many to go straight and how many to cut, then just repeat the process in the actual spot of the wall. That way all of the cuts would be at the end of the wall you wouldnt see, instead of the center of the wall that you *will* see. And it would also ensure all the blocks are level, as I would be going from one end to the other instead of trying to meet up.

Today Ill try the wood idea, along with reversing the water level. If I get the same readings, then at least I can be pretty positive Ive determined how far off I am. Then its just a matter of fixing it.

I think in order to do it "right" you're going to need to remove all of the blocks, dig your foundation, fill it, get it ready, level, and start from the middle. Of course it depends on whether you're the type that will look at it every day and curse yourself for not spending an extra few hours on something that you'll see for as long as you own the house.

I am the type that will swear at it, but I still think there has to be a way to make it work the way I already have it.

And I still dont know the path of the foundation anyway, which is why I didnt start digging the whole thing first. I can get somewhat of an idea, but without lining the blocks up against a square wall I wont really know until they are laid down. And if I try that, I can easily figure out how to continue working from the end I started on, instead of having to meet in the middle. Another advantage would be that all cut blocks would be on the side you dont see....if I had started the traditional way I would have cut blocks on each end....would look fine, but could be one of those things that you swear at with the wall standing for the rest of the time Im in the house :)

Perhaps you can lay out the blocks and then mark the path, remove the blocks, and dig it? That would allow you to lay it out the way you want and still do it "properly" and level. If you only want cut blocks on one side (won't you have to cut one in half to get them to overlap on your uncut side?) then work from the other side only and dig as far down as you need to ensure that it is level.

Sometimes building something twice sucks, but it means you got really, really good at it :)

The way we build walls is to lay out the outline first, figure out where the LOWEST point is, and start from there. So if you have 6" blocks and the lowest point is 32" below the slab, you do the math and figure how far down your footer needs to go.

Your easiest way to lay out the footprint of the wall is to run a stringline for each side of the wall, perpendicular to the slab. Measure the distance between wall faces, as laid out with string; half this dimension is your radius. Now, set a stringline at the farthest point of your wall, perpendicular to the other stringlines (so it's parallel to the slab edge). Measure back towards the slab the same distance as your radius dimension, center up between the sidewall strings, and pound a stake. Pop a nail in the center of the top of this stake. Hook the end of your tape measure on this nail, walk it out to the radius dimension, and paint out the arc to where it meets the side walls, and then paint any straight section back to the slab. The beauty of this is that while you're digging the footer and getting the base course up, you can leave all the stakes in place, so you can keep double-checking where you need to be. I don't care how good someone is, this is the only reliable way to get a smooth, consistent curve with no flat spots.

As for levelling it- if I didn't own a transit, I'd totally rent one for this project. Even if you have an 8 ft bubble stick, that's not enough to span the distance you're talking about, and every time you move it- especially if the 2x4 you use has a shwank to it- you're losing accuracy.

If, as you've said, it'll bug you, you may want to consider redoing it now. I slapped up my back steps last year, because I was in a hurry and it was way too cold out to mess with carpentry; they bug me every time I go in or out the back door. They're coming out this summer, and my wife is not exactly thrilled about it.

Ive measured the "length" of the slab as 20.5', which would make my radius measurement 10.25'. The original intention *was* to have a "flat spot" in front, this was before I found out the minimum radius on the blocks was so large (6' minimum). HOWEVER, the 6' minimum seems to be if you put the angled side of each block together, whereas Im putting the angled side of one block to the flat of the next block, etc. This makes the radius some unknown figure......Im not sure if it doubles the radius to 12' because Im at about 10' right now and the curve seems close to "levelling off" to a straight run.

As for levelling, Im pretty confident in the water level but I might try and track down a rental laser builder level (I dont know how to use a transit, and that itself can induce some error).

Remains to be seen if I start the whole thing over or not. I have 3 days of nice weather coming, but with kids and a wife that probably wont be enough time to completely start over :)

Is this a pin system, or a lip system?

Lip system, so its a somewhat set radius.

Actually let me clarify, its a lip system with 2 lips on the bottom of each block one in the back and one in the center.