masonry

[DNBEA]

the masonry foundations need to leave dowels for the wall above. I think we engineers usually dont tell the locations of the joints in the wall. and the blocks at joints are little bit longer than normal blocks, am i right? then how do we locate the dowel locations accurately if we dont know the joints locations? thanks

 

[jike]

We specify spacing and if dowels are req'd at ends or other locations.

GC must coordinate with his masonry sub. If not, then he is going to wind up cutting alot of block and probably will receive a backcharge from his sub.

 

[civilperson]

Blocks or CMU use 8" integer increments with the reinforcement centered in the core between the webs. The masons are very skilled and can adjust the mortar to produce the correct length of wall with the correct number of block to match your design layout of blocks/joints. The head joints are 3/8" +/- and the +/- is the answer to your question.

 

[DNBEA]

I have seen structural foundation plans in which all the dowels are shown. do you usually do that or just put notes like #6@16?

 

[jike]

We just call off spacing and additional dowels such as openings, ends, etc. make sure you call it off on foundation plan as well as wall plan. If it is just on wall or framing plan, they may not provide footing dowels. Make sure it is clearly shown on wall section also.

 

[DNBEA]

thank you guys

 

[UcfSE]

Residential plans in my area often show each bar location in the wall. Commerical plans will typically call out a spacing only and show any "special" or additional bars required in addition to the typical bars.

 

[concretemasonry]

If you do call out the specific dowel locations instaed of just the spacing, you must know what kind of block will be used. This is very true if one contractor does the concrete (including dowel placement) and another does the masonry. If there is only one contractor doing both, he would be responsible for coordination.

Just specifying units meeting the requirements of ASTM C90 has no bearing on the shape of the units. There are at least 3 different "non-priority" block configurations used for basement construction:

1. An "H" shaped unit with no molded core, but has 2 half cores and one center web that forms a core space when the block are laid. The webs in the wall are 16" on center when laid. This is used for fully grouted walls. - Readily available in the western U.S. and in selected eastern areas.

2. A double "H" shaped unit that has one molded core and two half cores that form additional cores when laid. This is a true modular cored unit with webs at 8" on center when in the wall. The perfect web and core alighnment maximizes the strength and permits individual cells to be grouted as necessary. It can be used for fully grouted or partially grouted construction. It is also used for walls where the cores are filled with insulation. - Available through progressive U.S. and international manufacturers.

3. A tradtional unit with 2 molded cores, with or without partial end cores. The webs do not align perfectly, but are adequate for partial grouting in most cases. If the first dowel is located properly and reinforcement is in increments of 16" on center, there is no problem with a conflict between the dowels and the block webs.

There are also some other units that are rarely used such as an "H" block with an offset center web, or single core units consisting of a large center core with smooth ends. - Limited availablity.

Dick