# How to cut out 7" thick concrete foundation wall



## nateo (Mar 1, 2010)

Hi there. So my dream is to build a garage bump out. However the foundation wall raises 6" upon the garage floor. Ideally I'd like to remove a 16' section of this foundation wall so the new floor in the bump out would be flush with the existing garage floor. I googled around for large concrete saw but the hand held ones (that can cut horizontal) only go to a depth of 5" or so. However this foundation is 7" thick. How would I go about making the horizontal cut (on a budget)?


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## ddawg16 (Aug 15, 2011)

That is going to be a tough cut....but doable..

I would use a concrete blade in your circular saw to cut as much as you can on the stem wall. Do it from both sides. If you are off a little....not a big deal. You won't be able to get all the way to the floor inside.

I'm assuming you can excavate the dirt on the outside to get full access.

Use this to get to the floor on the side cuts. Yes, they make concrete blades for sawzalls.










On the outside, run a caulk line where the floor will be. Assuming you have dug the dirt back and can get your saw in there....cut it as much as you can. you are only going to get about 3 1/2" deep. 

On the inside, use an cut off grinder with concrete blade and cut a slot along the edge of the stem wall. !/4" deep or so should be good enough.

Then grab the sledge hammer. You are going to be doing some major carnage to break that stem wall out. The end result is going to be rough looking. Chisel out the high spots, use cement to fill in the holes.


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## nateo (Mar 1, 2010)

I watched a youtube video of a sawzal cut with one of those blades. It looked like a pretty slow process and he was only couple couple of inch thick material. I like the idea of grinder and sledge hammer though, that might work.

I wonder how much it would cost to have someone cut it with one of these? https://www.youtube.com/watch?v=r2thO1e8kvM#t=29


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## ddawg16 (Aug 15, 2011)

It is a slow and messy process. Me being the cheap bastad I am as well as "I can do it", I'd do it my self. I figure it would take me all day.

To pay someone? No idea. They won't be able to use a large saw shown above...no way to turn it sideways. It will all have to be done by hand.


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## rustyjames (Jul 20, 2008)

If it were me I would hire a sub contractor that specializes in that type of cutting.


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## stadry (Jun 20, 2009)

that's a hydraulic hand saw probably cutting 10" deep by making 5 passes of 2" ea,,, pro's use a diamond ring saw, 14, 20, & 24" hand saws + track mounted wall saws,,, 16 horizontal ft suggests wall saw + hand saw for the vert cut(s),,, figure $4 - $5 per inch foot in atl

howzabout making your inside vert cut, go outside & saw into that cut, then drill a series of holes on the btm of the opening to create a weakened plane ? that's IF you need to do this yourself 16' is a lot of conc but you can then slide & dice on the ground,,, me, i'd hire a guy who's got the equip & have it done in 3 hrs :thumbsup:


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## nateo (Mar 1, 2010)

stadry said:


> that's a hydraulic hand saw probably cutting 10" deep by making 5 passes of 2" ea,,, pro's use a diamond ring saw, 14, 20, & 24" hand saws + track mounted wall saws,,, 16 horizontal ft suggests wall saw + hand saw for the vert cut(s),,, figure $4 - $5 per inch foot in atl


I googled that diamond ring saw. that thing looks bad-a. I'm going to have to agree. I think a thousand bucks for a clean cut done quickly sounds reasonable.


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## ron45 (Feb 25, 2014)

You can rent one..HD
PRO Gas Concrete Saw 16"


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## Doc Sheldon (Nov 23, 2014)

ron45 said:


> You can rent one..HD
> PRO Gas Concrete Saw 16"


Wish I'd had one of those available when I did my block wall cutout... I basically did what ddawg suggested, with my circ. saw and a concrete blade, then tried to wear out a 20# sledge... came out okay, but it was an all day affair. This would have made it a one-hour project!


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## MTN REMODEL LLC (Sep 11, 2010)

ON a budget........

Why not just drill the heck out of it with a Bulldog and a 1/2" bit.... maybe every 3"..... the bit will cut flush to one interior edge and any angle will cut deeper to the outside....and smack it out with a sledge.

(try knocking out a section and you may discover you can space your drilling further apart.)

(16 feet... unless your concrete is really high PSI, I'll bet you can have that drilled in 2 hours)

You are going to be pouring a new slab for the new garage... just use a surfacing cement on your hacked up stem wall.

I would not try with a cam type concrete drill.... get a bull dog and a good bit..... it will be less than half the cost of a saw rental... and you'll love the bulldog that you own in the future.

Best


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## sixeightten (Feb 10, 2009)

MTN has the right idea. Make a few cuts if you can, then drill about 4" apart with a good sds bit. You don't need to have a perfect cut there.


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## Bondo (Dec 8, 2007)

nateo said:


> Hi there. So my dream is to build a garage bump out. However the foundation wall raises 6" upon the garage floor. Ideally I'd like to remove a 16' section of this foundation wall so the new floor in the bump out would be flush with the existing garage floor. I googled around for large concrete saw but the hand held ones (that can cut horizontal) only go to a depth of 5" or so. However this foundation is 7" thick. How would I go about making the horizontal cut (on a budget)?


Ayuh,..... Same answer as in this thread, just down the page,....

A concrete chainsaw,.....


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## stadry (Jun 20, 2009)

don't think i'd want to drill " holes 2" o/c for 16' using a bulldog-class hammer-drill - i can see that taking all day,,, that 16" blade will cut 5 1/2" - still not deep enough for a pass from 1 side only :no: good luck to the op :thumbsup:


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## MTN REMODEL LLC (Sep 11, 2010)

stadry said:


> don't think i'd want to drill " holes 2" o/c for 16' using a bulldog-class hammer-drill - i can see that taking all day,,, that 16" blade will cut 5 1/2" - still not deep enough for a pass from 1 side only :no: good luck to the op :thumbsup:


Staydry..... I might be optimistic with a two hour estimate.... and it will depend on the comp streath of the concrete.... but a good sds bit and my bulldog on 2500-3000 psi stuff will eat up that concrete....

you're in a garage, and can flood/water your drilling with a garden hose....

and you can step up to a heavier duty Bosch if you need to....

The idea is prncipaled on budget considerations.... contracting it or a concrete saw will certainly give the OP a better finish cut (maybe close to flush which he'll have to chip out additionally) but seems he really doesn't care about that as he'll be pouring an additional slab anyway.

Good luck to the OP

Best


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## jogr (Jul 24, 2007)

Cut the 5" horizontal cut into the outside of the 7" thick wall 10" to 12"down (so your new slab will sit over the cut out area). Cut your vertical end cuts from both sides (5" +5" is greater than the 7" wall thickness) so the exposed vertical areas will have clean cuts.

Then take a big sledge and wack the upper inside of the section you are removing, striking away from the slab. Start at one end and work your way across the 16'. It should break of easily. The first two inches will be rough but will be covered by the new slab. The only part you need to cut neatly are the ends that will show. The rest is covered by the new slab.


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## stadry (Jun 20, 2009)

i'm learning lotsa new ways to do this but honestly i'd hate to make a living using a bulldog-class h/d in 7" conc :furious: it just doesn't have the balls to get thru 7",,, sds, improved sds, sds +, sds max, or spline bits won't make any difference 

did this work for a living in nyc/nj/ct/pa,,, we'd have gone broke w/some of these methods :whistling2: we had to be competitive & still make a living w/o the luxury of the work being ' h/o-diy ' class


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