How to cut a concrete basement floor?

[Jeff396]

Hi all,

I'm in the process of finishing my basement. I need to cut a trench in the concrete to plumb in a sewage pump and to put in the actual basin. I had though I would rent a concrete saw but all I can find are gas units which would put out too much exhaust. Any other suggestions on how to cut through the floor fairly neatly? I had also thought about a jack hammer but I sure would think scoring the outline first would make a nicer job of it.

Jeff

 

[kenmac]

You can buy a concrete blade for your circular saw. It has worked well for me. Use a mask though, makes alot of dust. For the basin you could use a 1/2" hammer drill with a contrete bit & drill holes around your mark for the basin & break it out with a sledge hammer.

 

[beenthere]

Jeff
I'd be more concerned about the fine dust that gets everywhere, than the fumes (can open windows to get rid of them).

One cheap way I remove dust is to put 20"x20" furnace filters on the intake side of 20" window fans setting near the area being sawn. Draping the area in plastic helps too, but that dust will find ways to get through most anything.

The last one I did when putting a basement toilet in, was just using a maul to break up the concrete. Could get a pretty good edge to concrete against when finishing it up. Some dust and chips of concrete around, but not as bad as a saw will make.

Also, you may get a saw that uses water to keep the dust down, but then getting rid of water may be the reason you are doing this in the first place. /forums/images/graemlins/wink.gif

 

[_RaT_]

If you can do a good job of ventalating the room then a concrete saw would be cheap and fast. You of course would need a wet vac to continually pull out the water. Some concrete sawing companies use hydraulic powered saws on walls, perhaps a call to them might get you some answers.

 

[Deerlope]

Is this an actual sewage pump or a sump pump to get rid of water only. Either way you can rent an electric diamond core drill. There are 12" and bigger core for them. If you buy a diamond blade for you skill saw and just wet the floor that will keep a lot of dust down. Beleive me I have cut a lot of concrete.

 

[Jeff396]

It's an actual sewage pump for a complete bathroom. Not only do I need to make a 20 or so inch hole for the basin but I need about 12 foot of trench to get the plumbing over to the basin.

Jeff

 

[Farmwithjunk]

I'm an estimator for a general contractor. My background prior to moving in to the office was as a carpenter. We do a lot of concrete construction. (parking garages, ect.) I've been on site while concrete sawing was taking place, so I know a little about what makes the most "live-able" conditions.

First off, we can't own the right equipment to saw concrete for what we can rent or sub out the work for. The company we contract cutting and coring with has hydraulic saws with diamond blades. The power unit stays outdoors. The blades are water cooled to also aid in keeping the dust to a minimum.

Their rates are based on thickness of the slab X the legnth of cut.

Sometimes the effort to "do-it-yourself" will lead you to spend too much or make things more difficult than need be. I'd at least call a concrete sawing contractor for a price. You might be suprised.

 

[jim_wilson]

I used an 8.5 inch Skilsaw with a diamond blade in it to cut thru my foundation wall when I wanted to add a wider door into my basement. It DOES make a lot of dust though. The hardest part of getting thru the concrete in the floor is getting started. A couple of years ago I also had to do a similar thing to what you are talking about - except I needed a trench across the basement from front to back to put a sewer hookup in. I ended up just using a sledghammer to break thru the concrete as I dug the trench across the floor. The concrete on my floor was only about 3-4 inches thick though - if your floor is 5-6 inches thick this probably would not work for you. You can rent core drills at Taylor Rental centers - or you can use a rotating combination hammerdrill to put some holes into the slab then use a sledge to break a piece out to get started on your trench. Just pounding on the slab will not do a good job of breaking thru - if you can get started however and then dig the dirt out underneath the slab some you might be surprised how easily a sledgehammer will break up the concrete.

 

[Jeff396]

Thanks all! I'm going to give a couple of these suggestions a try tomorrow. The slab is about 4" thick as I drilled a couple of 3/4" holes thinking I would try outlining with the hammer drill and then break it up. That wasn't practical as it took soooooooo long to get just one hole made. Will report back on how it goes.

Jeff

 

[gotrocks]

Jeff,
I have used a DRY CUT Diamond blade on my portable hand saw.
To keep dust down I have turned on the hose to a slow trickle and let it flow into the cut. The last trough I cut was kept straight by laying a 2x4 down as a guide,
that way you don't have to worry about loosing your chalk line mark.

Yes I know and hope you do know the <font color="red"> danger of electrical shock </font> . /forums/images/graemlins/blush.gif
I,ve done this a few times without a problem. As far as shock, I have had more problems while working outside after a hard rain and having the plug fall into a wet spot.
If you don't like the wet version, then get a good shop vac and have someone move the hose along in front of your cut, that will get the majority of the dust.
Good luck and Happy Holidays!

 

[VA_Joe]

I did something similar in my floor by using one of those wear type masonry cut-off wheels in my circular saw (home depot sells them for about $5 - I used up a few of them) to cut a shallow groove (one inch?) around the area that I needed to remove and then used an electric chipping hammer (rented from home depot for about $40 for a half day) to break up the concrete. The chipping hammer made fast work of the concrete (I finshed with the chipping hammer in about an hour or so). Have some bolt cutters handy to cut the steel mesh reinforcement. Good luck.


Joe

 

[Mike_C]

I had to do something similar, cut a trench through 30 feet of concrete. The abrasive blade in teh circular saw idea was never going to work, unless I bought 100 blades.

The solution was to rent an electric jack hammer for $50 / day.
I just kept punching holes next to each other then connected the dots. It worked well and was cheap enough. Sure, the edges were rough, but after filling it back in with new concrete and a skim coat on top noone would ever know.

 

[VA_Joe]

The only advantage of scoring the surface with the abrasive blade is that it keeps the cut neat (i.e. contains surface cracks/chipping). If you plan to put something on top of the floor (like a rug) then these won't be seen.

 

[Jeff396]

Well I got it done.....turned into a bit of a mini disaster. I ended up scoring the top about 1 1/2 inches deep with the masonry bit in the circular saw. That was a lot easier than I expected though I don't think the saw appreciated it too much. Then I rented a jack hammer from HD. I tried my best with the maul but it wasn't touching this stuff. Even the jack hammer wasn't going through it like I'd experienced when breaking up drives and walkways. I think this is the first time I've busted up that fiber reinforced cement. So I return the Jack Hammer and clean up which was no small job either. Now I cut the pipe that was pre plumbed under the floor which I want to tie into and re-direct to the basin. As I'm looking at it I wonder if my eyes are messing with me but it sure looks like the stub for the shower (up stream) is lower than the end I am going to tie into (down stream). I decided to pour some water in the toilet fitting and see what happened. Sure enough, all of the water ends up draining out of the shower pipe.......DOH!!!!!!! So now I have to head back to HD and rent the Jack Hammer again and buy another masonry blade so I can remove all of the pipes and completely reinstall them!!! All this because my moron builder decided, on his own, that I might want to put in a pool some day and moved the septic up the hill level with the first floor. Forget that the basement pre-plumbing was already set to have the septic on the basement level. Along with having a communicationally challenged builder it didn't help that we built this house from out of state and couldn't keep an eye on it like we usually do. I'm just sure glad it was pre-plumbed to save me some work not to mention the money! /forums/images/graemlins/tongue.gif

Oh, and I ended up using the 20" fan with a furnace filter taped over it idea. It seemed to work real well to grab some of the dust the shop vac with the drywall bag wasn't sucking up. Going to file that one away for future projects! /forums/images/graemlins/grin.gif

Jeff

 

[Jeff396]

Another pic.....

I suppose I could have re-plumbed it to go directly from the toilet to the basin but I didn't want to figure out how to change the venting.

 

[Jeff396]

Our Castle.

Thanks for all of the help and suggestions!!

Jeff

 

[Jagmandave]

Beautiful home!

I rented one of those electric jack hammers from Home Depot too, and was surprised how well it worked, I took out a 35 year old 20' X 20' patio that was some of the hardest concrete I've ever busted up!

 

[OKnewguy]

It sounds like things went well. Then can be alot of work. You got lucky that it was not super thick, I remodeled 2 bathrooms and had to move some drains around, in some area's the slab was over 1' thick. I guess they had leveled out the slab with the concrete, instead of leveling out the base.
Man that was work, I am not to happy in this pick, I was exhausted.
DAve

 

[Jeff396]

Well, I sure am glad mine wasn't that thick!!

Here's a few more pictures of my progress. Pipes are back in and ready to bury. I'm going to get the cement today and hopefully have it in over the weekend.

Jeff

 

[Jeff396]

and another.....