New Cinder Block Wall about a Half Inch Higher then Old Wall

Hi everyone,

I am adding a small extension about 36" out x 36' long to extend my kitchen, office, and dining room. It will have a footer and block wall (8"). I am about half way up on the block and noticed that once I am complete the top of the new block will about 1/2 higher (following my normal 3/8 joint). The final course its 4" solid block. My question is should be worried about this? The top of the block should be on the same plane.

I was thinking I would either have to grind down the solid 4" block, or could maybe plane the new sole plate? Thoughts? Comments?

 

It would be best for it to be the right height. A thinner top plate is one option, using a 2" cap block and more lumber is another. You could also try for slightly thinner mortar joints.

 

Yes, the top of the new and existing black should be in the same plane. I would suggest using an angle grinder with a diamond blade and cut 1/2" off the course of hollow block below the solid block. In fact, you may consider taking a bit more and adjusting your mortar joint thicknesses; that gives you some tolerance in case it's not perfect somewhere else.

BTW, how are you planning on setting anchor bolts with a solid block as the top course?

Edit: Just saw marksr's post. Good point, if you have enough mortar joints, you could thin them up, but I would be sure your joints are no less than 1/4" thick.

 

Don't you just set them between the cap blocks with the L portion turned under the block? That is how I've always done it but then I'm a painter, not a mason.

 

I've always wanted anchors grouted into a full block cell. Assuming a standard 2 cell block, if the anchor bolt goes through a mortar head joint, it'll hit the web in the block below, rather than going into a cell. That's assuming a true running bond; but maybe appearance isn't a factor and the solid can be offset. In the OP's case, I would have just used a half high top course or (even better) put the half high course below a full height top course. Could also put the solid block below a full height top course with the 1/2" + that's cut off at the bottom against the 4" high course. Lots of options.

In any case, it's my opinion that taking 1/2" off a treated plate won't be easy and really doesn't give much to nail to.

 

Guys thanks for all the ideas so far!

I have 3 more mortar joints in the 4ft wall left. Basically 2 full of 8" block and my 4" top block. If I made the joints 1/4 inch, I could save 3/8 total. and that would put me back inline. However, I am not a mason and though the smallest joint size I could use was 3/8? This would be a pretty easy fix.

The grind option if 1/4 inch joint don't work. If I grind down the full 8" block its only the outside walls. Better yet I could use an angle grinder and cut as well. I'll have to do that for a lot of blocks but it would be far easier then my original thought to grind the 4" solid blocks. If I hadn't picked up 4" I could have bough 2" then just used more motar but materials are on site already.

The j-bolt issue. I thought about drilling a hole in the middle of the 4" solid block (wide enough to center and plumb), then have the 8" block below filled with mortar (I'll need some mesh below that course) and then place my top block and align the J-bolt. Marksr idea is interesting though, I believe he is saying to use the joint (avoiding my hole idea) and pretty much the same, fill in the block below with mortar.

Now today I thought, couldn't I place the 4" cap block below a row of 8" block. This way could then fill my empty voids and set the j-bolt. This would also mean I wouldn't have to pick up mesh since the solid block would stop mortar from falling.

Attached are 2 options. Mind you if I am able to use 1/4 joints I won't have to grind/cut the block down.



PS do they sell 8" wide rolls of mesh or am I stuck with cutting the sheets down to size?

 

The biggest issue with leaving the top open is it would be a catch all for dust/debris and bugs. Right or wrong when I only wanted to fill a partial block I just stuffed drink bottles in it and then added my mortar or concrete mix.

 

1/4" joints certainly aren't ideal, but I've seen it done; I would play it safe and go with standard 3/8" joints. If it were me, I would actually cut down the block, rather than try grinding. I could be wrong, but I think it'll be easier. I also think option 2 is better; then put the cut edge down toward the 4" cap so any inaccuracies in cutting are taken up in the mortar joint. It also makes it easy to fill all the cores if you want to.

Marksr, you name it and I've heard of it pushed into the core: bottles like you say, roofing scraps, poly, the list goes on! It only has to last long enough for the fill to mostly set up.

Edit: I THINK what marksr means when he talked about between joints is the bolt would still be centered on your 8" wall, just put between the end joints from one 4" block to the next.

 

So looking at the code 1/4 inch will work:
Bed Joints +/- 1/8 inch (or: 1/4 inch to 1/2 inch)
Head Joints -1/4 to +3/8 inches (or: 1/8 inch to 3/4 inch)

Bruce great thinking. If I do cut, putting the cut edge down makes leveling simpler and neater.

You guys both mentioned using whatever to fill open web of that top course (if I use the 8" open block at the top) its just has to hold enough till the mortar dries. That would be cheaper then getting mesh and cutting.

Could I possibly cut some tar paper (heavy weight) and put it between the courses (not covering the outside walls of the block just the inside web? I have been mortaring the outside of the block and the web connecting points on the inside till now. I may also be able to just run my durawall on that course and then slip in small chunks of tar paper, they should technically get held up by the wires. Option 2, would take care of this.

 

If you're putting the 4" high block in the position of option 2, than the solid block is what stops the fill. Otherwise, just wad up whatever you have and force it down into the open cell. Your Durawal would also help hold the stuff in place. If you wad up enough of it and your mix isn't too soupy, the fill will stay put and won't run past.

 

Thanks for all the help guys, think I will go with option 2