 Level
I've poured quite a few foundations over the years, and it's nice when they come out either dead level or sloped to the degree you want. In practice, this rarely happens right on the money. I'd lay out the first course of blocks, then use shims to bring them up to level. Measure how much you're off on this first course, memorize, then lay your mortar bed to make up the difference. I'd use Type S and brick sand, three to one. In reality, if the weather is with you and your mortar is not too sloppy, you will be able to make up, say, half to three-quarters of an inch in the first course. No worries, the mortar will still set up an cure at that thickness. You can even leave brick shims in place in strategic places, mortared down, not dry. As you go up, course by course, you can make up any small error until you reach level. This niggly method will save you a lot of time and hassle at the slab stage. Block is very forgiving in this way, unlike brick. Just make sure to use a block pointer once the mortar sets up but is not dry. This will ensure that your joints are full and tight.
If you don't have one, buy a line level at HD, line corner blocks (probably have to go to a masonry supply for those), and a good nylon line. Once you're above the first course, set your line level and work too it. Also, a four foot level is a good investment for this sort of work.
Jim  |