# concrete block house with SBC: roof question



## Sparticle (Nov 1, 2004)

We started out building a dry stack block house but soon discovered how irregular the blocks were. We have been mortaring instead. The rules for dry stack walls say that the roof must go on after the surface bonding cement goes on. Since this is no longer a dry stack wall, can the roof go on before the SBC? It would be nicer to have a covered area in which to work. By the way, its an underground house.


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## SteveO (Apr 14, 2009)

Sorry you still need to follow the rules you also need to grout the cores and put the bond beam or 2 in the middle of the wall (I can;t remember how far up or how many courses and the bond beam at the top to hold your roof down. We ended up hanging a tarp on some 16ft 2x4 to work under.
That sun sure makes it hard to coat wet the wall with a garden sprayer it will extend your working time.
If this is a underground don't you grout all the cores????
Steve


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## cowkeeper (Feb 17, 2007)

When using the dry stack, surface bonding method, you need to shim the blocks to keep everything straight. Brick ties work well for this, flush with the wall of course. FHB had some excellent articles on this method some years ago.ck


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## Sparticle (Nov 1, 2004)

We know all about those shims. Stacking these blocks dry was ridiculous! The blocks were so bad we gave up after 3 courses and started mortaring. 

Yes, we have a bond beam on the 7th course and there will be one up top. We're not filling all of the cores but are filling some. 

Why, since the wall is so strong with concrete and rebar everywhere, can't the roof go on before the SBC?


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## ErinP (Aug 23, 2007)

If you're doing mortared joints, why are you surface bonding??


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## texican (Oct 4, 2003)

ErinP said:


> If you're doing mortared joints, why are you surface bonding??


Same thinking here... 

If you need shade, I'd stretch some pine poles over the structure, and tie tarps, shadecloth, or whatever, over the work area. I haven't done much on my new home lately, (it's over 100 here already...) but when I do, there's a couple of upright poles with greenhouse shadecloth stretched over the work area, for shading.


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## kvr28 (Feb 15, 2009)

I recommend filling all the cores with cement, you'll sleep better at night, when we drystacked ours we cut a bond beam in the 3rd and top course and dropped rebar into each corner and about every 6 feet. 










We hired a pump truck for 700 dollars and I think it took 13 yards of cement, so the cost was right around 2000 dollars, I'm glad we did it










due to the uniformity issues, I cut square shims out of aluminum coil stock and used those to shim the blocks, that was the biggest pain in the whole process. This was taken the morning after I finished stacking, felt good to be done










good luck with your project


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## kvr28 (Feb 15, 2009)

and if you mortared all the joints the sbc is going to be wasted time and money, the sbc works by creating a thin shell with fibres tying together the joints, with the mortar gap, your loosing the reason for applying the sbc


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## Sparticle (Nov 1, 2004)

Thanks for all the replies and advice. 

We only mortared under and above the blocks, not on the ends of the blocks, thus the need for the SBC. 

The mason laying the blocks said the roof can go on 1 week after the bond beam is poured.


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## speedfunk (Dec 7, 2005)

Yeah block irregularites are a pain. In the future I will use corner blocks only as they are much more square and were A LOT easier to stack. 

As far as the roof I can only speak to my own experience we put the roof on before we finished the surface bonding cement and no issues. Actually there is still part with none on it. To be honest I think it makes a better product. When the roof is on it it puts weight on it. If you parge the walls before hand (which some spots we did) they stressed the sbc and made hairline cracks. The spots where we waited till after the roof was on , they "settled in" with the weight of the roof to where they were at ease . We then put the sbc on and it seems to work better. Just my experience. 

I will have to look at your blog posts.... congrats on getting started


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## SteveO (Apr 14, 2009)

I must agree with kvr. If you are not grouting the whole thng you still need to insulate the cores you are not grouting it is must simpler to just fill it all up. I usually grout every 5 courses. Just makes it easier.
Steve


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## kan-green (Oct 20, 2010)

Spartical,

I just finished reading your blog as I am planning to build using sbc. Are you planning on putting up pics and any lessons learned?


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## Sparticle (Nov 1, 2004)

I plan on it, but with the gardening, doing farmer's market and the house; there hasn't been much time. I'm rarely even on HT, my DH uses the screen name much more than I do.

I was hoping to get a post done soon though.


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