# Forum Home Renovation Sub Flooring  Bracing to concrete stumps

## Ashwood

Anyone know what's the best way to install bracing (eg. using structural pine as bracing) to concrete stumps? The stumps are quite tall (1.5 to 1.8 m). Need to do this to provide lateral stability. 
Unlike wooden stumps, you can't drill into the concrete stumps to use coach bolts. Are there special brackets? Does anyone have photos to share? Thanks.

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## brynk

gday ashwood 
you can set anchors into the base & top of the concrete columns by drilling holes & setting with chemicals threaded rod into the concrete itself. (read this post for a discussion on the method - http://www.woodworkforums.com/showthread.php?t=60690). 
onto this you can bolt some hefty steel brackets for joining the pine to the concrete. i would consider the use of a hardwood over treated pine, myself, as the joint-strength capacity of the hardwood will be much greater 
r's brynk

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## thebuildingsurv

You can buy "u" brackets with a thread and nut on each end, they are not very thick probably about 3mm. A mob that sells them also sells the stumps that are only 100mm square but go to about 1.5m high i think they are called hi-stump or something like that. I would not drill concrete stumps.

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## Ashwood

Thanks.  
I've seen the "U" brackets, but they look really skinny and also as if it would slide a fair bit as well before they hold secure. 
I had a look at the thread from Brynk, but still can't visualize the chemical anchor process. Any photos or internet links?

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## thebuildingsurv

If you start drilling into to stumps they will probably fall apart. I have seen it happen, stumps are very fragile. With the U-Bolt system you can put a piece of timber down the side of the stump with about 3 U-bolts and attach the brace to that, if you are worried that the brace will slide. Ring the manufacturer see what they recommend. The building inspector probably wont appreciate stumps being drilled into. Why dont you ring your building surveyor.

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## brynk

gday yes buildingsurv raises valid concerns about the potential for old concrete to be brittle which i had not considered. what condition are the stumps in? what aspect of the footing-stump-bearer structural member has weakened to require the bracing?

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