8" Wall Size

jaymay75

Can I do an 8" CMU Block foundation. My engineer says I can do it, but I don't see it done around here much. I'll have up to 7 foot of dirt against it. I will also vertical rebar every 32"

joasis

What is common in your area? If the engineer says "do it" does it mean he will state it on your plans?

rino1494

I would never use anything under 10" on a foundation, especially with 7ft of dirt against it.

8" would work good on a garage, but not a foundation.

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jmic

Being from the Northeast I'v seen what winters and frost can do to block walls. I wouldn't do anything less than 12" in blocks. Look at it this way if you don't have a good foundation under your home, you won't have much will you?

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Joe

denick

Jay,

An 8' high 8" block wall with 7 feet of backfill should probably not be more than 24' to 28' long with minimal reinforcement and grouting. Designed right it could be longer.

The three things that determine the longevity of a block foundation in my opinion are the footing, mason's technique and backfilling.

Properly prepared, poured, finished and cured footings are a must!

If block are laid with the proper joint spacing and mortar mix ( read the post on it) for the correct bond strength and reinforced and grouted properly there should not be a problem?

The exterior treatment of the block, the material used in backfilling, time given for mortar curing and the backfilling technique are more important than the block work.

I can take you to homes in CT and NY that were built in the 20's 30's 40's 50's and 60's that are as good as any concrete foundation done at the same time.

Are you going to do the block work?


Nick

tkle

Roughly off the top of my head.Orco .com has specs.Steel is cheap compared to concrete,I use a lot of it.


7' retaining

vertical #4 16"o.c.
5 courses of 12's at the bottom
horizontal #4 2' o.c.
4.5' wide footing with 6" toe & 1'x1' keyway
5.5 sack mix
solid grout