Today I laid the first row of block (no mortar) on top of the footings to locate and drill holes for the vertical rebar. Everything was going surprisingly well until I got to the only inside corner on the foundation and noticed that the last block came up 5 1/2" short of the corner block adjacent to it = footings are not square. I can make it work by moving the angle of the block wall but the block would not be sitting in the middle of the footing. Should I cut a block and mortar it into the 5 1/2" gap or should I move the block around and have the block not sitting in the middle of the footing? If I move the block far enough to close the gap the block will be about 1" from the edge of the footing. What do you recommend?
Thanks
Mark
Is the problem caused by not using mortar? I think the blocks are short for mortar to make them the right length. In that case if you are using SBC you'll likely have to fill the space, as I see it from what I think you described.
I see what glenn is saying. When you laid the block on dry run did yo allow for mortar between the joints or lay them end to end?
I think "square" is more important than being centered on the footing. Start by laying only the corner blocks for all corners ... keep moving the blocks about until you have everything square, then you can fix these corner blocks in place on a mound of mortar. I always lay the corners at least four blocks high before I start filling in the walls between the corners. The first row should make the corners "square", the second row should be "square and level". ... and then on from there.
But before laying the corner blocks, you must know which direction the blocks should be. To determine this, I would suggest making a "to scale" drawing of the first row of blocks. (Use some of that drawing paper with the pre-printed blue grid ... 1/8" by 1/8" squares ... or 1/16" by 1/16" squares ... available in large sheet pads to make the task easier.) Draw a rectangle for each block. Keep adjusting-correcting the drawing until you get a "fit" that you like. If you are lucky, you will only use full blocks ... but it doesn't always work out that way. After you have a drawing that works, you are ready to place the first blocks in each corner.
Mark
I concur with JRR that it is more important to have it square than trying to keep it centered on the footing. That is why a good set of batter boards is usually set at the onset of the foundation and re-used until the foundation is complete. The only thing you don't want is a large overhang of the block on the footer edge.
Diagonals are often substuted for the batterboards when laying block. I start by laying the corner blocks in both directions (dry fit). Then move accordingly to get the diagionals. Then mark all four corners in both directions.
Build all four corner and then lay to each filling in the middle. Depending on how high the foundation is will determine how high each corner can be laid. On a crawlspace you should be able to lay all four corners to the required heigth and then fill in. I have never done the dry stack but you have to take into consideration that a standard block is 15-5/8" and it works out to 16" with a 3/8" mortar joint. With that said if you are laying 10 blocks long then you are going to be short some 3-3/4" for that run. Just a rough guess but you can see where I am going. All four sides will have this deficit. The longer the individual side runs the more of the deficit. I think I am right about this. d* If you decide to use a shorter cut block IMO I would figure it where you are using two cut blocks of larger length rather than one small one. This will have to be done on each course.
Red'
You say.. (The only thing you don't want is a large overhang of the block on the footer edge.)
If I move the block around i can get it to work out and the block will be about 1" from the edge of the footing. Would that work?
Thanks
Mark
IMHO it wouldn't hurt providing that you have the full depth of the footer and not just the top of the footer overpouring of the earth(sidewall of the footing). In essence if your footing was poured with a good straight sidewall then it will transfer the weight to the entire footing. Basickly you will have the majority of the 7-1/2" width block on the main part of the footing.
There was one location on mine that was fairly close to the outside edge but solid. The perfectly laid off footing will go astray once you run into rocks and have several step footings to make like I did in multiple directions. I was satisfied with the outcome and after two years there is no noticable sign of failure in the block wall.
(https://i220.photobucket.com/albums/dd161/redoverfarm/hightop/100_0869-1.jpg)
Hi Mark,
If I read your question right, your footing isn't square. When blocks are laid on the footing so all your walls are square and correctly placed, your blocks over hang the footing. Are you saying the length of the footing or a short distance? If it were me, I wouldn't worry about it being a little off. You can rotohammer the footing and epoxy rebar to the side of the footing and pore the footing wider to correct. If it is only a few feet I may not even care. I may be wrong here, but I don't think it's too big a problem.
As Long as your blocks are on the footings and not hanging over you will be fine.
On my little cabin the blocks are not square to the footings.
You can make spacers to lay your blocks out by cutting up some 3/8's plywood.
Use them in between each block to set up your dry run then you will know were your corners will end up.
You can get a blade for your skillsaw to cut your blocks if you need to.
http://www.dixieline.com/blocks/concreteblock1.html
keep it square,W
Thanks for all of your replies. I went to the cabin again today and I took your advice in it being ok if the block does not sit in the middle of the footing. I moved the block around and it looks pretty darn good, not perfect but pretty good. I laid all of the block out and drilled and epoxied 4' of #5 rebar vertically every 32". It was snowing and again it was a sloppy mess and again I was so muddy when I got home that when I got ready for my shower I noticed mud even in my underwear. HAHA Nothing like chasing the kids around with muddy underwear!!!!!!!
I will post pictures soon.....(of the cabin)
Thanks
Mark
The streak....
http://www.youtube.com/watch?v=eIPv9AtZ2zE
Mark, I may have missed something in the posts, but have you dry set all four corners of the first course of block, and then diagonal measured both ways to check for square?
Mark:
I wouldn't feel too bad about the out of square problem. My neighbor's son hired a pro to pour his foundation. Only problem was when finished it was 6" out of square (one end to the other), so bad that they had to scab on an additional concrete block wall, drill and epoxy the block to the existing foundation, then fill it with concrete before they could start framing. Later they found out the concrete floor wasn't nearly as flat as they thought. I think it took like $400 in thin-set cement to get the floor flat enough for the ceramic tile to look right.
So, by comparison, your problems are small.
Now, as for the concrete block stuff. As the others said to do, I built (dry-stacked) my corners first; then just filled in between the corners by stacking whole blocks. On many (almost all) rows I had to cut one block to fill-in that last little, remaining space. I remember reading somewhere that if you lay ten block end to end, the wall will still come out 1/8 to 1/4" longer than you expected. So, trying to design it all out with drawings and planning exactly how many block you will need in each row still won't get you exactly where you want to go. Just do the corners first, make then square and plumb, and start in-filling with block. This approach works. Any little imperfections will disappear once the surface bonding cement goes on. Once you get to the bonding stage, read my blog, because there are a few tips in there I had to learn the hard way.
I know someone who built a huge straw bale house 2' (feet) out of square. :o I can't even imagine the headaches...