concrete footer


Old 10-29-06, 07:05 PM
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Talking concrete footer

I am adding a porch to the front of my house. It will be placed in an existing corner (thereby requiring two outside edges) and will be elevated 16". I am also adding a new sidewalk.

1. When calculating my concrete requirement, is there a standard volume used by the pros for filling my supporting hollow core (8x8x16) block walls?

2. My footer will only be 22' long (15x7). It would be quite costly to have the concrete delivered just for the footer and then come back after the blocks are placed to complete the rest of the pour, so here's my idea in question:
If no local code prohibits it (of course), is there any reason I should not / could not first place hollow core blocks side-by-side the entire length of my supporting walls (22' - 33 blocks) to act as the footer and then install the two rows of blocks end-to-end on top of the footer row, with mortar? I would add vertical #5 rebar every 32".
This would allow me to be ready for only one pouring because the pump truck alone will cost about $500 (the concrete truck cannot get to the front of the house without causing damage).

3. I want to line my sidewalk with 1-3/8" pavers. I would also like to run a line of pavers across the sidewalk every (4 or 6?) feet to hide the expansion joint.
Do I place a board on the edge of the sidewalk that depth after the concrete is poured or before? If before, how should I go about mounting it?

Thanks for whatever help you can provide me!
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Old 10-30-06, 07:35 AM
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concrete footer

Best to to it the traditional way. You do not need two truck deliveries.

1. If you fill ALL the cores the "magic number" is about 50% for filling cores or 8" block. There is not a good reason to fill all the cores for your situation.

2. Order ready mix (3000 psi minimum) for the footing, which should be below frost or at the locally required depth if no frost. Put two continuous rebars in the footing. You can lap bars about 24" to get the same effect as a continuous bar.

3. Lay the block with mortar (Type M or S). Add a vertical steel rod where desired. Set anchor bolts where needed for your P.T. sill plate if you are building a wood porch. Fill those few cores later with gout you have mixed using some Quikrete bags (not many).

Separate the sidewalk from the structure with a compressive material. You will not be puting in expanasion joints - you need control joints. You can saw control joints in the slab very soon the next day (much easier) after pouring to give the sidewalk a clean appearance.

Depending on the amount of sawing, you can rent a saw or use a masonry blade on yours. To be effective, the sawed joint should be 1/4 to 1/3 the slab depth.

Old 10-30-06, 09:20 AM
Join Date: Mar 2006
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1. .26 CuFt per Block.

2. No, that is not an acceptable footing.

3. Yes, lay the board across to blockout for the pavers, then sawcut on one edge or the other of the blockout for your control joint.
Old 10-30-06, 05:32 PM
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concrete footer

Thanks for responding ... I visited our two largest national hardware stores today and the guys were guessing at how much concrete a block holds (and they were way off the .26 mark).

Again, thanks a bunch, really. It's great to learn from people who know their stuff!
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