Concrete Wall, Slab, and Core Cutting
Concrete cutting is big business. Whether it is a concrete wall or slab that needs to be cut, or cores that need to be drilled, concrete work is always holding up some other type of contractor from doing their job. This is a job that demands attention to detail and tremendous respect for the tools that you are using. Detail is important because once the concrete is cut, that is it. There is no replacing a concrete wall if you made your cut in the wrong place. Same goes for safety. These guys work with huge saw blades powered by big engines. One loose bolt on your rig can spell disaster, for you and the equipment.
Concrete Wall Saw Cutting
Cutting a concrete wall is no joke. This is a dangerous job but the risks can be nearly eliminated with the proper precautions. First of all, for safety reasons, you should always have at least two people on the job site. Working with a huge saw like that by yourself is never a good idea. A second hand always comes in handy for carrying equipment and helping with the clean up process as well. Not to mention that the section of concrete wall to be removed is extremely heavy and sometimes requires two people to get it to flip over. Now that we have the safety precaution out of the way, some of you are probably asking "why do you need to cut a concrete wall?" The majority of the wall cutting I did was to provide a doorway from an old foundation, to a newly poured foundation for an addition to an existing home.
How does the saw work?
The saw in the video is operated by remote while the one I used to use was operated with a hand crank to control the depth of the saw blade and a simple forward and reverse lever to move the saw up and down the track. There was also a knob to control the speed of the saw blade as well. Needless to say, it takes a lot of practice to operate one of these concrete wall saws. The first thing to do is to measure the area to be cut, this will determine where the tracks will get attached to the wall. Next, if you are working on a finished home, you need to check the are for any wires or pipes that may be in your way. Third, you need to ensure there is nobody working on the other side of the wall.
If you are a homeowner or contractor and need to have a concrete wall cut, here are some pointers to make everybody's lives easier.
- If at all possible, have the wall cut away before the floor is poured for the new foundation. This allows you to just bury the slab and not have the extra cost of hauling away the concrete.
- When possible, do the cutting on the outside of the foundation. It is easier to clean up outside than inside.
- Have the job site excavated beforehand.
- Remove the siding from the house above where the wall is being cut away. The saw blade needs to cut above the outside of the wall to complete the cut on the inside. A section 12"-18" above and 6" or so on either side of the section of wall should suffice.
Concrete Slab Cutting
Concrete slab cutting is somewhat similar to wall cutting, except the saw does not run on a track. Also, since the majority of slab cutting is done outdoors, there are gas powered saws available. Since the saw does not run on a track system, a neat slab cut can be a little trickier. The saw will have some type of guide on it and it is up to the operator to keep the saw running along the line to achieve a nice straight cut.
Concrete Core Drilling
Coring is a form of drilling, but instead of using a giant drill bit, it uses a hollow bit. Think of it as a saw blade rolled up onto itself to form a circle. The reason for this is:
- it is not as messy
- it saves money
Cutting or drilling concrete is messy. If you do not use a wet saw or drill (feeds water onto the blade while cutting), you will create an enormous amount of dust. The blades and core bits are also all diamond tipped to cut through the concrete. By using a core bit, there is less area to cut through meaning you don't need as many diamond tips.
Coring is usually done after the foundation or wall is in place and there needs to be additional access through the wall for pipes, wires, or ducts of some sort. Like a wall saw, a core drill is mounted directly to the surface you are coring through with an anchor and a piece of threaded rod. This setup allows one anchor to be used for numerous holes to be drilled. Once they are done, the anchor hole can easily be covered with a little bit of patch cement.
Whether you are cutting a wall, slab, or doing some coring, you need to be aware of rebar in the concrete. Rebar is short for reinforcing bar, it is the steel rods that are used inside of a concrete pour to add strength to the concrete. Diamond blades cut through concrete very well, but if you manage to hit a piece of rebar going the wrong way down your cut, you'll be in for a long day.