Cutting concrete out of my foundation

Old 09-14-03, 07:08 AM
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Cutting concrete out of my foundation

I'm going to be cutting a double door opening and window openings into my 8" thick poured foundation. I have a Walkout Basement so all excavation has been completed. The top of the windows will be about 12" from the top of the foundation.

I have all the equipment (Concrete blades and saw) and a experianced person (This is a bigger project than he has done in the past) helping me.

I will be doing a dry cut which will require me to cover all air vents to the furnace and upstairs to prevent dust from entering the upper floors.

Are there any other special issues to keep in mind while doing this?

Any feedback would be welcomed!

Ron B
Old 09-14-03, 10:42 AM
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If the house is finished, do you have any idea of the load on the wall you are cutting? Even 12 inches of concrete cannot take a very heavy load when spanning 6 feet. If the opening was planned and adequate rebar was placed to create the header beam you are OK. If extra rebar was not placed where the header is going to be you will need a lintel of some type.
Old 09-14-03, 10:52 AM
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I assume you are referring to a cross beam as a cap over the door and windows? I do not know the load on the wall and I want to take any resonable steps to prevent damage to the foundation and upper structure.

I have researcehed a little more and the addition of "Beam pockets" above the opening to add a steel or wood support member for added structural support sounds like a good idea.

Any tips on how to make sure it fits in well enough to actually support the upper floor?

Thanks in advance!

Ron B
Old 09-14-03, 11:28 AM
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I hate to rain on your parade, but what you are doing is going to be not only very difficult, but structuraly a difficult project. Even with rebar, concrete is a very brittle animal. This is how I would do it. Measure the heigth of your rough door opening, and draw it on your concrete wall you want to cut out. Now mark an extra
6" on each side and 8" on the top. Also draw a line where the cen ter of you door will be. Now cut on the outside line you drew, and the center line. Only do 1/2 of your door at a time. After you cut out half your door, put in a 6x6 beam, and post jacks. Now cut out the other half and do the same. That way you only have1/2 of your hole exposed to strength failure. Make sure you put in a 5x6" beam or post on the wall end to hold up your beam above the door before you cut out the second door.

Now for cutting out. This is a terrible dirty job. You will have to cut from both sides on the exact line in order to make a clean cut.
Unless of course you are borrowing a bar concrete saw, but I am betting you are not. You can only cut 5" deep at a time. When you get to the inside, open a basement window, put a big fan at the window to draw out the dust. When cutting you will only be able to see only a few inches. You must wear good dust masks,
and I even mist the area while the cut is being made. This dust will be in your house for about a month. I cannot express enough how bad the dust will be in your house after cutting, no matter how good you seal things. Lots and Lots of luck.
Old 09-21-03, 03:47 PM
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Here's a possibilty in dealing with the dust issue, I'm not saying that it would work for sure or that you could find a company that would do it, BUT what about phoning a few duct cleaning companys, the've got the suction and the filters, might be worth checking into. Then after, they could do your ducts as well.
Old 09-21-03, 09:48 PM
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Use plastic sheeting to seal-off the area to be cut. Hold the sheeting down with sandbags, duct tape, etc. Create a hole in the wall, perhaps using a core drill. The hole or holes is for venting the dust to the outside.

Set up a blower (perhaps renting one of those carpet-drying blowers) and pressurize the sealed-off area. The dust will seek a path out, hopefully the holes you cut in the wall.

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