Aggrevating Variation in Block Size

[edsiajb]

Re: Aggrevating Variation in Block Size

And because my height works out better without the mortar joints...

[edsiajb]

Re: Aggrevating Variation in Block Size

Why are you people shying away from laying the block with mortar? You are going to lay the most difficult part of the build with fireclay. Laying the base with mortar would get builders used to handling the tools of the trade.

Maybe because the plans recommend dry stacking and filling every other core with re-bar and concrete?

[Campmaki]

Re: Aggrevating Variation in Block Size

Why are you people shying away from laying the block with mortar? You are going to lay the most difficult part of the build with fireclay. Laying the base with mortar would get builders used to handling the tools of the trade.

[Tscarborough]

Re: Aggrevating Variation in Block Size

I didn't say they were GOOD block, just within tolerance. If I put those CMU on a job, I would not be selling many block.

[edsiajb]

Re: Aggrevating Variation in Block Size

In the past, when I've used block before, I believe they were much more uniform in size (and squareness). Yes, I understand that is one of the purposes of mortar.

But if I have a block 1/8" short and the next block is 3/8" tall, that is a 1/2" variation causing a 1/2" gap, and would look rather bad even if mortar were being used between the block.

As all of this will be covered in a yet-to-be-decided finish, I'm not really that worried about it...just aggravated.

[david s]

Re: Aggrevating Variation in Block Size

If you chip off the little dags on the bottom of the blocks you will get a more uniform size. If you are not mortaring between the bricks an alternative is to use a masonry adhesive and some 5/16" washers placed at strategic places will keep the work level. The first row of bricks should have a bed of mortar between them and the foundation slab.

[NCMan]

Re: Aggrevating Variation in Block Size

If you can live w/what you have, you can always adjust your formwork for your hearth slab to be square and level. Once the slab is poured and is square and level, the block work won't matter. Just be sure to fix it at that point and not let it go. Unless the block is real bad, it should just be a few minor adjustments to your form work to get it right, in my opinion.

[Tscarborough]

Re: Aggrevating Variation in Block Size

Now you know the purpose of mortar. Those dimensions are well within standards for CMU, although the slumps units sound pretty crappy.

[edsiajb]

Several days ago, I began dry stacking my block. All of a sudden I realized that my block had a good deal of variation in height. They should be 7 5/8" tall, but some of them are from 1/4" to 3/8" taller than they are supposed to be!

There is also surprising (to me anyway) variation in the other dimensions. Some of the block are not square top to bottom - and sort of lean out or lean in.

Needless to say, the stacked block look bad...with big gaps here and there. I always thought concrete block were more uniform in size.

Is this a common issue?

Should I try to fill the gaps with mortar before I pour the cores?