Anchor a concrete curb wall to an existing slab

Simon96Taco

Hi there,

I currently have a garage built upon an existing concrete slab (I believe a plain 4" slab, no foundation wall at the edges). The framing currently sits on an untreated 2x4 wooden sill plate.

I'm considering either

a) replacing the 2x4 sill with a pressure treated 2x4 sill or

b) Cutting the bottom 8" of the framing and retrofitting a concrete curb wall, using 15cm wide, 8" tall, 16" long bond beam (like this: http://www.homedepot.ca/product/15cm-sm-bb-grey/969057#).

A is my much easier option, B is my much more difficult option.

In addition to the complication of lifting the garage to place the bond beams under, my biggest question mark is this - how do I anchor this new bond beam curb wall to the existing slab? Do I just drill holes into the slab at prescribed intervals and epoxy in a piece of rebar?

Given all the difficulties, I'm strongly favouring option A at the moment, but want to ensure I fully understand both of the options before making my final decision.

Thanks in advance!
Simon

GBrackins

wouldn't matter which way you go, wood than is in direct contact with concrete needs to be pressure treated or expect it to rot.

where are you located? location gives us information to determine a proper course of action based upon weather conditions and sometimes building codes.

__________________
Gary

"You get what you pay for, and sometimes free costs more!"

Simon96Taco

I am located in Calgary, Alberta, Canada.

Cheers,
Simon

GBrackins

I unfortunately am not up on the National Building Code being the in states, so I won't be much help on code compliance.

I would recommend discussing your project with your local building department. without having a foundation under your garage you will be subject to frost heave. Myself I'd probably just go with replacing the sill, and then only if it is rotting. You could treat the lower foot or so of the exposed wooden studs with a preservative treatment to prevent any issues with exposure to water.

Good luck!

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Gary

"You get what you pay for, and sometimes free costs more!"

jomama45

Obviously, option B is more work, but it would be a far better long-term solution. If I were doing it, I'd drill & epoxy galvanized threaded rods every 4 feet into the existing slab, lay the block (BB's would be overkill IMO if you epoxied), set a new treated sill (with sill sealer under it) over threaded rods, tighten down, and possibly install an additional plate over the treated plate to give yourself more working room.

TRUEPRO

Yet the problem remains- Structure over 4", not mono. Now what? We can add a million bbs and a million more treated BPs but 4" isnt long term.

Please, by all means, correct me if im wrong but here is the PROPER course of action=

Dig down and under existing 4 inches of slab approx 8" inches back and 10" down.

Drill 3/8 holes every 48" and insert 10" pieces of threaded rod. This rod will act as a plate anchor AND tie the new footer to the existing slab.

Granted this is quite the workload but never the less, do it right the first time?

I have never implemented this method but i have a similar (repair) job i am bidding on now- Some idiot built a 2 story detach over a 4" slab. Hmmmm what to do...

Simon96Taco

Thanks to all for your responses.

What I'm struggling with is the idea of throwing all the expense/labor to do the best possible repair job on a garage that might only have a total lifespan of another 15 -20 years.

The 4" slab is cracking already, which discourages me from building the concrete stem wall on top of it. I think what I really want to do is just peel back the wood siding that is at grade so it doesn't rot, and replace the sill with pressure treated.

What I don't know how to deal with is how to protect the sheathing which will now be exposed near ground level (as it won't have the wood siding over it anymore). I'm thinking of cutting the bottom 12" of sheathing and replacing with pressure treated, but that is going to look ugly. Maybe I can paint it with some sort of (preferably white in colour) rubberized paint?

Thanks again for all your feedback.

Simon