Instructables

building cinderblock wall... questions questions questions

I'm considering building a small cinderblock wall off of an existing concrete slab.  I have very little clue what I'm doing, but I'm a fast learner.

Question #1:
Do I need rebar to hold the blocks, or is mortar mix enough?  They won't be "weight bearing" as it will only be a partial wall around 3' tall.  If I do need rebar... hammer drill? all the way through slab? pound rebar in?  Note that the blocks will be just about flush with the edge of the slab.

Question #2:
The area I want to create a wall for is covered with a roof (four- 4"x4" posts, about 10' x 12'... roof is around 12' high) so the blocks will butt up right next to wooden posts... is this kosher? I guess in my mind, this precludes a cornerstone, and makes the courses hard to offset (I don't know what to call that... the center of the second course blocks sit on the edges of the bottom course blocks), and what is a good way join block to wood?

Question #3:
Can I use the small blocks (4x8x16) or will they just topple over (see question #1 again), and if I should use the normal cinder blocks, how do I make a corner with 4x4 posts already there?

...likely more questions to come :)

Re-design3 years ago

This should give you as starting point.

The blocks should be anchored at the bottom with rods drilled into the slab in 4-5 places each side.

Every other course should have  horizontal reinforcement like "durawall".  It's a wire lattice work that is embedded into the mortar.

The ends and corners (at least) should have a couple of rods1/2" -5/8" in the core and filled with mortar to top to make a tying column.

THe top course should be  "lintle" blocks with  continuous horizontal reinforcement.

Sizes are just for example your mileage may vary and you should get local answers from and expert.  THis is just to give you an idea what is involved.
OtisDrftwood (author)  Re-design3 years ago
I saw that video, and I noticed they do not use rods, which is why I asked. I can understand rods for a load bearing wall, but if it's just a partial wall, I feel like I can forego the rods. I just don't want to start drilling into the slab and end up cracking it if I don't have to.
Drilling into the slab shouldn't cause the slab to crack. If you don't have any anchors the wallis just sitting on the slab and is likely to move off the slab when the wind blows hard or it gets bumped by the riding lawnmower or just fall over. It's not going to be anchored by the roof and ceiling framing at the top like is usual in a small shed like this.
OtisDrftwood (author)  Re-design3 years ago
how far beneath/above the slab surface should the rods go? I need to find a good picture of how they should be aligned with the blocks...
6" is plenty.