Author Topic: Should I dry stack my foundation or mortar the joints??  (Read 17707 times)

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Offline 2zwudz

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Should I dry stack my foundation or mortar the joints??
« on: May 07, 2008, 02:32:32 AM »
   I will be starting my cabin this month and I would like some advice or opinions?  I was thinking about dry stacking my foundation with concrete blocks,vertical rebar with concrete in the cell and surface bonding cement on both sides. I am also  considering doing the regular mortar joints with the surface bonding cement.  Which one would you recommend?  I live 85 miles away from the site and will be doing the work with my 14 and 12 year old sons when we can.
Thanks Mark

Offline glenn kangiser

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #1 on: May 07, 2008, 06:27:18 AM »
N74TG - Tony did the dry stack and liked it - then pour the bonding columns and beams - should hold it together with the surface bonding. 

If you did mortar joints I would just pour the bonding beams and not worry about the surface bonding.  Probably depends on what you want the outside to look like.
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Offline JRR

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #2 on: May 07, 2008, 10:54:07 AM »
I once tried dry stacking and did not do so well.  Then I discovered that its recommended to buy a special flat surface block made for dry stacking ... and I was using regular blocks with their usual surface imperfections on top and bottom.  My regular blocks would not stay in a straight line ... some would move about as I tried to apply the surface bonding cement.

Then I switched to mortar joints just to keep the blocks fixed together and at the normal 3/8" spacing.  The mortar joints weren't pretty ... and just troweled flat because they were to be covered later.  This operation went along much faster for me (compared to my dry stacking effort).  It allowed me to complete the entire wall before beginning the surface bonding ... keeping an even appearance thru-out.  I also choose a few strategic block cells to insert a re-bar and fill with concrete.

I've used this method on two buildings thus far.  I'm comfortable with it now.

Offline rdleisey

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #3 on: May 07, 2008, 06:17:43 PM »
If you are considering using drystack construction and have not visited the following site, you will find a great deal of very useful info of the subject.  Hope this helps.

http://www.drystacked.com

Offline MountainDon

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #4 on: May 07, 2008, 06:47:15 PM »
 w*  rdleisey

Thanks for that link.  :)
Just because something has been done and has not failed, doesn’t mean it is good design.

Offline JRR

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #5 on: May 08, 2008, 07:28:25 AM »
That is a good link.  I just wished he had not use terms to imply that a surface bonded wall is "water proof" or "damp proof".  Certainly the surface bonding will help resist liquid water flowing "thru the wall" ... but I'm not convinced there is much less wicking of dampness, either up from the earth beneath the footing; or horizontally from backfilled earth.

Offline n74tg

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #6 on: May 08, 2008, 05:26:48 PM »
Surface bonding cement has calcium stearate in it.  This is what (they say) makes it waterproof.
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Offline speedfunk

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #7 on: June 19, 2008, 11:47:07 AM »
We built our foundation dry stacked..  It is very simple..esp if your building with unskilled labor..  Just get the corners true and it goes up very easy.   We actually like it so much , the house we are building next will be all dry stack block
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Offline apaknad

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #8 on: June 19, 2008, 01:46:10 PM »
hi all,
 pardon my ignorance but what is drystacking?
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Offline Erin

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #9 on: June 19, 2008, 01:54:11 PM »
Basically it's exactly what it sounds like.  You just stack your concrete blocks up.  No mortar to "glue" them together.

Once they're stacked though, you use a special type of mortar on both sides of the wall though that binds the whole works together. 
The wise woman builds her own house... Proverbs 14:1

Offline n74tg

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #10 on: June 19, 2008, 06:57:11 PM »
Apaknad:
There's a little more to it than just stacking up block.  You also run rebar vertically inside some of the block.  And before that you embed the rebar in the concrete footer.  Use a 1/2" rebar vertically every four feet of wall length.  Then you fill the cells that have rebar in them with concrete.  And then you put a "bond beam" on top. 

I did all my foundation drystack.  Read about it at the blog address below.  Description starts with the 2006-12-03 archive post.
« Last Edit: June 20, 2008, 03:49:43 AM by n74tg »
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http://n74tg.blogspot.com/

Offline apaknad

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #11 on: June 20, 2008, 04:00:15 AM »
wow, i never even heard of this technique. how does the strength of this compare to other ways of building  and can you make a basement doing this and is it a one man do it yourself type project? ??? thanx for the link, it is interesting.
unless we recognize who's really in charge, things aren't going to get better.

Offline n74tg

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Re: Should I dry stack my foundation or mortar the joints??
« Reply #12 on: June 20, 2008, 05:18:37 AM »
Strong, I think I could drive a bulldozer over the top of the wall and it would stand up fine.  And all that vertical rebar and concrete inside that ties the footer to the wall; well, I don't see how that could do anything other than make it stronger than a conventional wall.

The problem (as I see it) with a standard (mortared) block wall is that they work fine in compression (holding up the weight of the house above it), but lousy in tension (if tornado/hurricane winds try to lift/push the house off the foundation, or if seismic forces try to shake it off the foundation sideways).  The steel in the walls holds it together (in all directions) so it keeps the house connected to the foundation in all/more different type situations.  And the surface bonding cement (besides making the wall waterproof) hold all the individual blocks together (ie glues them together).

Now the other problem I have with mortared walls is you're trying to make the mortar act as a glue to hold the block together.  Mortar is lousy in tension.  Example: I've seen several homes built in this city where they built up foundation walls (maybe as high as four to five feet tall).  Then they came back in and filled the interior up with dirt or gravel so they could put a concrete slab on top of it.  Call it an elevated slab if you wish.  Now, before they got the slab poured it rained (big rain) and all that water filled up the pore spaces between the dirt particles inside the foundation walls, and made it all very HEAVY.  The foundation walls couldn't hold up the weight and the weakest wall just collapses outward.  When you look at the collapsed wall you see that the concrete block didn't break, the mortar joint between the blocks broke.     

I agree there are a lot of people that don't know much about drystack walls; and a lot of them are contractors.  But, drystack has been around a LONG time (think of the pyramids).  Furthermore, the way a builder/contractor learns his trade these days is by on-the-job training (learning from his boss).  If the boss doesn't know it, the apprentice can't know it.  Add to it, that the building trades in general are very resistant to change (most of us are) and you build a situation where different techniques seldom get tried even if they may be better. 

Can one person do a drystack wall?  My foundation is 30' x 57' and goes from 3' high on the shallow end to 8' high on the deep end.  I built it all by myself.  It will help to have an assistant when pouring/filling the bond beam on top of the wall, but all the rest of it can be done by one person. 

Read the material at the drystacked.com website and read my blog.  You can do this.
My house building blog:

http://n74tg.blogspot.com/

 

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