In this video I show you how to cut a basement floor and control the concrete dust. This will be helpful for people trying to figure out how to add a sink or even full bathroom to their basement.
Before cutting into the concrete, prepare for what can go wrong.
Two Things That Can Go Wrong When Cutting Your Basement Floor
- The Main Stack is Too Shallow
Drain lines need to slope at least 1/4 inch per foot of drain. That means 10 feet of drain line needs to drop at least 2.5 inches. Depending on how far the new drain line needs to be from the existing sewer line, the existing sewer might not be deep enough. This means you’ll have to raise the floor around the new line, or pump the source of the new waste to the main stack using a macerator pump. - Drains Aren’t Always Straight Lines
Don’t assume that because a drain is a straight line from a main sewer stack that the drain connects in a straight line to the sewer stack. Until the sewer is exposed, it can be anyone’s guess where it actually goes.
Skilsaw Medusaw Review
For this project I used a dedicated concrete cutting saw. People have different opinions about whether or not to score the concrete before breaking it up, but I think it makes the job easier and cleaner to patch. The Skilsaw Medusaw has a water inlet to keep dust down and a vacuum outlet to extract debris. I simply hooked the saw up to my dependable Ridgid shop wet vac and it handled everything I could’ve hoped for. This saw reduced the dust I would’ve experienced cutting with a DIY rig by probably 90%.
To cut ~25 linear feet of trench I did use two diamond cutting blades. I used both a continuous and segmented blade. The segmented blade lasted about twice as long:
The saw I used: Skilsaw Medusaw
The concrete cutting blade that worked best: Bosch Segmented Diamond Blade
The wet vac I used: Ridgid Wet Vac
Bauer Demolition Hammer Review
Once I scored the concrete the demo hammer did the rest. The basement floor slab was 2″ thick. It took me a couple hours to break up the ~12 foot trench and clear the debris away.
I bought this Bauer Demolition Hammer at Harbor Freight for $335 with a two year warranty. I spent another $40 on tips for the demo hammer. I bought the warranty because I was skeptical that the cheaper Bauer could do the job for half the price of the Bosch equivalent. But it did! I kept the wet vac close by the demo hammer tip at all times and the dust did not get very far at all.
Here’s a link to the Bauer Demo Hammer I used: Bauer Demolition Hammer
The hammer comes in two versions, one with a trigger, the other with a toggle switch that keeps the hammer on or off. I can’t speak to why they have two versions, or if there’s a functional advantage, but I have the trigger version and it worked out great. I give the tool 5/5. I’m looking forward to using it again. At 21 pounds its almost 15 pounds lighter than the lightest jackhammer, but is still powerful enough to break up 2″ thick concrete.
How to Patch Basement Concrete
Once I backfilled the drain I used crack resistant commercial grade Quikrete. 150lbs is roughly equivalent to 1ft3 of concrete. So run your calculations accordingly (and double check those numbers if you end up needed many bags of concrete).
To mix the concrete I use a Ridgid Mixer. Although you may be able to the concrete with a normal drill and paddle mixer attachment, this drill is significantly easier to use as it’s designed for the task at hand. Yes, you can also mix concrete the old fashioned way in a wheel barrel by hand, but this really is worth the investment if you plan on using it more than once.
Here’s the Ridgid Concrete Mixer I used: Ridgid Concrete Mixer
