# what is the weight of a solid CMU



## AustinDB (Sep 11, 2006)

I searched CT and googled, but didn't run across the weight of a solid concrete block. 

Can you (by code that is) use solid CMU's for a foundation wall? The requirement (in my area) of securing vertically w/ rebar and grouting would not be possible.


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## Tscarborough (Feb 25, 2006)

74# in this area.


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## concretemasonry (Dec 1, 2006)

By code, a solid CMU is not solid. It has over 75% solids and can have cores. In the real world a contractor will use a unit with cores, even if the are samll.

The weight will depend on the type of aggregate, since some lightweight "solid" (75% solid) will have a lower weight that a 50% solid normal weight block.

since you are in Delaware, you may have the choice of lightweight block (possibly pumice) or normal weight, which will always be cheaper to buy, but maybe not to lay. The thinckness of the wall you are building will have a big effect.

Bottom line - check with the local supplier to give you an accurate weight of what they can supply in the thickness you need.


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## Crosby (Jan 11, 2009)

72chevy4x4 said:


> I searched CT and googled, but didn't run across the weight of a solid concrete block.
> 
> Can you (by code that is) use solid CMU's for a foundation wall? The requirement (in my area) of securing vertically w/ rebar and grouting would not be possible.


I'm curious why you can't reinforce it with re-bar and grout. At least get some horizontal reinforcement wire.


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## bwalley (Jan 7, 2009)

72chevy4x4 said:


> I searched CT and googled, but didn't run across the weight of a solid concrete block.
> 
> Can you (by code that is) use solid CMU's for a foundation wall? The requirement (in my area) of securing vertically w/ rebar and grouting would not be possible.


How are you going to attach it to the steel in the footers, where are your dowels going to be?

Why can't you use rebar, dowels and fill the cells?

A solid wall without dowels in it and rebar is going to fail, because only the grout is holding the CMU together.


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## concretemasonry (Dec 1, 2006)

Check above - A solid CMU is not 100% solid. It just must be 75% solid and most suppliers put in cores to save on weight and make them easier to use. The codes also do not require all core to be filled, but an architect may require it for fire resistance or sound control.

Many 4" block that are made today may be classified as solids since the % solids for a 4" block ranges between 72% and 77%.

Chevy -
It is hard to imagine why you can't use a cored CMU that is classified as solid. - You must have a real strange or backward code if they require a solid CMU (which can have cores - just smaller).


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## AustinDB (Sep 11, 2006)

I have seen solid block which have no cores, small or not. I don't remember the specifics, but seem to recall Kent county code dictating a CMU basement with two story's on top, requiring vertical rebar grouted in place, every so many feet-maybe every 4'???

back to the 'solid' block which has small cores-are they large enough to grout the rebar in place? I do not have experience with this type of foundation work and not doing one, just trying to learn.


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## rbsremodeling (Nov 12, 2007)

72chevy4x4 said:


> I searched CT and googled, but didn't run across the weight of a solid concrete block.
> 
> Can you (by code that is) use solid CMU's for a foundation wall? *The requirement (in my area) of securing vertically w/ rebar and grouting would not be possible.*




This can absolutely be done with a hollow block. I do it all the time. 

The block wall is tied into the footing and if it butts a solid wall it is tied into that as well


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## concretemasonry (Dec 1, 2006)

chevy -

Talk to your local building code people. They want to have you build the right way because it is much less work for them. Also, talk to your local producer - there several good ones in DE.

It is hard to imagine you have such an outmoded code (thay really have not changed in the last 30-40 years when it comes to basements and materials). I suspect it is because some people do not know that a solid block (according to all standards) is not 100% solid and usually has cores. The are also some units that are made 100% solid for appreance purposes.

I would never use 100% solid units for anything unless for sound or fire.

It is a very rare place in the world where someone (or code) would require 100% or over 75% solid (semi-solids in some local languages) block. It is just backward and poor construction.

Few masons will want to lay the old-fashioned (1920's era) block that are "knuckle busters" that are costly to use and provide very poor construction.

Your old Kent county code you recall may require filling cores periodically if you do not have an engineered design, but it is doubtful that it would require "solid" block to be filled.

In some countries they build 20 story loadbearing block buildings out of 6" hollow block with partially/periordic reinforcing and grout where required. The engineer there says "We use your codes, but we use them better".

You are getting bad information.


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## rbsremodeling (Nov 12, 2007)

I suspect he might be misinterpreting what he read


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## concretemasonry (Dec 1, 2006)

RB -

You are right about the mis-interpreting and that is why you have to go the local code people to get the correct information. They appreciate having some imput before there is a problem.

Trying to grout the wrong units is a start in the wrong direction for everyone. Any decent mason contractor should know the code and requirements.


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## kgphoto (May 9, 2006)

Wouldn't fly here, so check your local codes.


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