Stupid ?: CMUs, masonry veneer, basement

Apparently, I’m an idiot, because I’ve search and search and can’t find the answer, so it must be obvious to everyone but me!
How is a masonry veneer supported if you have CMU walls with a basement? If you have CMU walls on a slab, no basement, well, then clearly you just pour the footing wider. But a basement? Do you have the veneer start below grade? Tie in a second footer somewhere? Build with super-thick CMUs until you reach the level where you want to start the veneer and then switch to thinner ones? (And if so…well the ledge is supposed to be 6″ thick, right, 4″ for the veneer plus 2″ more for a gap? So 6+8 (typical CMU thickness) = 14″–where are you going to get 14″ blocks?) WHAT?
Sorry for the moronic question, but this is driving me crazy.
Actually, I’d love to see diagrams with things like the joists, etc., attached to CMU construction. (Ledger, right? But I’ve never actually SEEN it…) I am wholly unfamiliar with it!
Edited 2/1/2007 6:15 pm ET by Reyesuela
Replies
If you mean CMU walls above a basement block wall, then it's usually sizing--12" for trbasement walls, and then 8" above that, aligned to the inside. Bingo, 4" brickledge right around. While keeping a nice, simple, flat surface to the waterproofing.
I have seen, out in the under-regulated sticks, a course of 12" block on top of the 8" block wall to carry the veneer brick. I wouldn't try it on a dare, personally--but folks is funny when they get ideas in them.
If you mean how to "ledge out" for the veneer brick if the floor deck is out flush to the oustide basement wall, well, that's trickier. Usually, that's poking holes in the entire course of blocks to get them filled solid with grout so that lintel (steel) angles can be bolted on the wall at the veneer brick starting elevation.
I've seen veneer brick started from the footer, and run up to where it goes, but we're back to peculiar things people do too. (The veneer brick needs to be grouted in soild, up to grade level, or the weep holes will just fill the airspace with very much unwanted water. In addition, just about anything is a better waterproofing for a basement wall than veneer brick.
Details has me thinking. You might try the Acme Brick web site; I also want to remember a brick masonry org/assn type site.
"I have seen, out in the under-regulated sticks, a course of 12" block on top of the 8" block wall to carry the veneer brick"wow (that reminds me of the old Charlie Chaplin movies where he's traipsing on the pigeon ledges of tall buildings)
pigeon ledges
AhHa! That is how I believe I will refer to such, actually.
Next time you take a drive out in the country and see some home hansomly veneered in brick, just think to yourself "Wonder if the brick ledge was even designed . . . ?" Better to not know the ones with no bar in the block walls; or no lintels for that second-story veneer; or . . . Occupational hazard of my occupation not being around (sorry Bubba)
My whole neighborhood has eight inch block to just below grade and then brick and four inch block.
Wouldn't do it my self or advise it.
I've seen that too--with both 8-in. poured concrete and with block. It can be done but it's a bad idea. If the carpenters use 4-in. of the foundation (to the face of the sheathing) and they have a 1 1/2-in band on the ends of the joists, it leaves just 2 inches of the joists bearing on the foundation. The masons, in the meantime, have to hang the bricks 5/8-in. over the edge of the foundation to get the necessary one-inch air space. An eight inch foundation is not enough, in my opinion.
How does the 2" bearing on the foundation differ from the second floor in 2 x 4 framing?
Like CapnMac said, use a 12-in thick foundation below grade. At floor level, the mudsill sits on the inside half of the foundation and the brick veneer continues up past it. You can begin the brick below the floor; it often looks better that way. Make sure you leave at least 4 5/8-in. from the face of the sheathing for the brick veneer. The bricks are 3 5/8-in. and you need a minimum of 1-in air space between the back of the brick and the face of the frame.
Around here NE Ohio we do most foundation walls with 8" block, usually 10 courses, then 2 courses of 4" for the veneer. The veneer sits proud of the block on the bottom and we grout a wash up to it (when we parge the outside of the block) for frost heave to slide past it.
Not sure why anyone would say they don't advise this method....properly grouted cells and pilasters are plenty strong..
Keith C
Ok! It just seemed strange to me to have it hanging over a bit!
I've found some specs now--no less that 2/3rds of a block must be supported on the ledge!