Concrete Block Usage

gladiatorxx

I have a garage which is set back into my tiered land, so the the grade of earth on the side walls is about 3 1/2 ft, then in the back its about 5 1/2 ft. I'm going to rebuild the back and side walls, also rebar and core fill them, question is when do you use a bond beam? How about a knock-out?

I have read that its a good idea to install rebar horizontal, i figured it was by use of a bond beam block or knock-out block

stacker

most commercial jobs call for a bond beam on the first course,then at 4foot and every 4 foot after that.

i would say on your job,one at four foot and a top bond beam.if you have 8foot walls.also vertical cells should be filled every four foot starting with the corner cell.one stick of number 5 rebar into each vertical cell filled.they should also be pinned tp the concrete floor.2 sticks of number 4 rebar in the bond beam.if you have windows or doors in the wall,a bond beam should be place over the opening ,extending 8 inches on either side with that cell filled,and bond beam filled.

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gladiatorxx

Thanks stacker, the info helps, now at 4 ft is you have a vertical rebar installed, how do you effectively continue up and connect the rebar above if the bond beam block is now at the 4ft mark, drill hole through to accomidate the verticals? The horizontals I can understand, but if you don't connect the through the bond beam isn't that a weak link now?

Tscarborough

That is where the knockout block goes.

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tkle

The verts would be extended up before you grout.

stacker

your vertical rebar would extend up past the bond beam at least 18 inches,like tkle says.
i have been on jobs where they want the rebar tied,to continue up.i dont personally see the need for that as long as you get a good lap.and like i say at least 18 inches would be enough.

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tkle

The purpose of tying rebar is mainly to keep it in position. Untied verts tend to get shoved against the webs. This clearance can be maintained without tying simply by keeping them in position while grouting. I think tying to the horizontals is more important.

brick4life

I don't know what your codes are but that is stroger than what they require on the coast in Ga. by the way lap for #5 rebar is 24" 30" for #6 18" for #4 according to all the specs. I've ever built by.Our codes are supposed to be for 125 mph windload anything under 8' bondbeam at top over 8' bb ever 8' or 8' and at the top depending on height of wall, verticals corners and 4' on center also,any opening over 6' we have to put a16"deep bb using either high channels or 2 courses of bb 2# 5's in top and 2 in bottom.

concretemasonry

The difference come from whether you need the location controlled.

If you are talking about vertical loads, having enough length and being close enough (same cell usually), that is adequate.

If you are talking about horizontal loads, the location of the primary steel (usually vertical) is important and can be handled by tying to horizontal steel if the rebar is put in during laying block.

Some engineers will detail the rebar to be against one face at the bottom and move it to the opposite face as the wall goes up.

Having the rebar near or in contact with a block web is not a problem. You may need to maintain a location or separation from a face shell for some applications.

It helps to use the right configuration of block for what you are building, unless it is not critical and just garden variety walls.

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gladiatorxx

Ok, since i am going to core fill the wall, I was going to use quickrete block core fill which is about 3000 psi at full cure, any other suggestions??

Also what would be the appropriate mortar type s or m??

gladiatorxx

One more thing, The original walls were unfilled 12", I plan on using 12" for back wall which is 6ft below grade (core filled), and 10" (core filled) for the side, which is 4ft below grade. I was going to change to 10" for the side, because my side clearance for the garage rough opening using 12" is about 3 3/4" which is too close, 10" will give me some more space, so we are not fighting the door clearances.

Any issues here?

Ed the Roofer

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