Concrete Block Observations

Now I’ve had the chance to lay some more blocks, and I have noticed a few things. Please jump in (in the comments) to set me straight if you know more than I do (which is likely, trust me…).

The directions on the mortar mix bags must be taken with a grain of salt (NOT LITERALLY). I’m quite certain that on my first batch I exceeded the maximum amount of water suggested, and yet my mix was still very gritty. And yes, I did mix it thoroughly. It really makes a huge difference to your enjoyment factor when the mortar mix is smooth and consistent. The suggestions that it should look like a milkshake are helpful. Of course, it should be thick enough to hold its shape, and not allow the block to just sink willy-nilly.

This brings me to my next observation – don’t buy mortar mix that has been subject to any sort of water! With concrete mix, I’ve found that I can sometimes break it up, or it breaks up well enough in the cement mixer. Mortar mix – not so much. On my second attempt at laying blocks, I had bought some questionable bags that felt like a solid brick. Opening up the first one, it broke up into large chunks that I was never really able to remove from the mix. By the end, I was sifting through the mortar with my fingers to pull out the pebble and stone sized pieces that refused to mix. It’s not possible to level a block when it is resting on a single “stone” of mortar mix.

Those little wooden blocks with strings that I made? They were totally crappy the next day. I tightened up the strings and was very careful, and still they would drop from one end or the other while I was trying to hook them on. Eventually I realized that I had all four corner blocks in place, so I just made a looong string that went around the perimeter of my whole project. I would do it this way again, even if the blocks were not yet mortared into place.

This string can sag though. I didn’t pay attention to that the next day when I again started to lay blocks. At the end of my day when I crouched right down, I realized that my first row of blocks actually dips a bit in the middle and comes back up – following the string which had sagged slightly overnight. I will tighten the string up again before every session of laying blocks from now on. I hope that I can make the mortar a little thicker in the middle for my second row and correct this. Thankfully I am only laying two rows, so I anticipate that my accumulated errors will not come to much.

Try to keep your mortar mix and blocks handy, so you don’t have to walk all over to get them.

Lucky for me, I plan on building a wraparound deck on both my structures. This should hide my sins nicely. I have to admit that my work doesn’t look the prettiest. I didn’t take any time to clean off excess mortar mix from the joints or where it has dripped. It should all disappear.

It seems to be more forgiving than you think. The mortar dried equally hard where I have thought my mix was either too dry or too wet. You just have to wait a few days for it to set up fully. I keep reminding myself that even if I simply dry-stacked these blocks, they would likely last a hundred years without incident. The mortar should ensure that they live a very long life.

Remember that there is a “top” and “bottom” to the blocks. The flared end goes up.

Vents that you can open and close are very expensive. When I first was quoted $20.00 for a single vent, I laughed it off and left. The next place wanted $30.00 for an even simpler vent! I opted for the $4.00 versions that you cannot open and shut, as I had planned on blocking them off with foam insulation each winter anyway.

That’s about it for now. I’ll get back to it later this morning and if I have anything new to report, I’ll try to squeeze it into my next blog post.


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