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  • cutting concrete - garage floor.

    Renting a gas-powered concrete saw this weekend. I need to cut out two 4'x4' slabs from my garage floor. Probably a 14" diamond blade.

    The floor is about 20yrs old, but appears subpar for a 2 post lift (http://www.maxjaxusa.com) that I am installing. I swear the floor was 4" thick when I did my 1/2" pilot hole, but when I rented the SDS-Max drill, I got less than 3.5", and the anchors won't hold.

    I'll be attaching the saw to the garden hose to keep the dust down, and have the doors open to vent the exhaust from the gas motor.

    For each section of the floor I'll be cutting out, I'll have 32' of cutting, I'm cutting each section into 9 18x18' pieces to make it so that it only mildly hurts when I load them into the trailer to take to the dump.

    How fast does a gas powered saw typically cut? 0.5, 1, 1.5, or 2' per minute?

    Never done this before,.... just wondering if I'll be able to do the cutting in a morning, whole day, or what......

    I'll probably rent the saw from Friday afterwork and return it Monday morning before work.

    Peter
    Pete C.
    http://blog.pjbj.ca
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  • #2

    Re: cutting concrete - garage floor.

    Re: cutting concrete - garage floor.

    It will depend on how much steel is in the floor. No way to tell that unless you X-ray or something.

    Comment


    • #3

      Re: cutting concrete - garage floor.

      Re: cutting concrete - garage floor.

      If you're cutting with a 14" quick cut and the proper wet cut diamond blade (a new blade for cured concrete) I would expect it done between half an hour and 45 minutes (your mileage may vary).

      If it was an employee I'd order the concrete for an hour after he started cutting, if it was me 2 hours minimum to cover time spent telling everyone how bad my back aches and how fast I could have done it in my prime. It depends on the blade and if you are able to use the saw continuously without fatigue. It should cut through a garage slab like butter. I would expect wire mesh at best which the saw will handle

      If you cut all the way through you'll only have to chip out the first chunk the rest will come easy. Don't be afraid to go over the lines to get a full cut, it'll look fine when you're finished. I use a 5' crowbar and a hand truck to move the chunks. You won't have to pick anything up and you can wheel them right into you're trailer.

      Comment


      • #4

        Re: cutting concrete - garage floor.

        Re: cutting concrete - garage floor.

        Is there an actual spec for the slab required to support the jack? Personally I would have structural engineer look at what you have and the difference in the actual spec. You may just need to mount it on a steel plate and bolt into your floor.

        Comment


        • #5

          Re: cutting concrete - garage floor.

          Re: cutting concrete - garage floor.

          Just like Dave said run past on the corners and only lower the blade barely through the slab. I'm asuming your renting a self propeled saw. Once cut out if the floor is not re-enforced you'll be able to break it into reasonble pieces to handle with a sledge hammer in mins.

          Bill

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          • #6

            Re: cutting concrete - garage floor.

            Re: cutting concrete - garage floor.

            Jim,

            The spec for the anchors (it's tension with a 2 post lift) is minimum 4" of 3000psi concrete for the floor. If it's not thick enough, or the concrete is not strong enough, then the recommendation is a 4x4' footing 10-12" deep. With the car up on the lift, the posts will want to tip in. the anchors need to be strong enough to not pull out of the floor.

            Bill,

            I was just going to rent the concrete saw (basically a large chainsaw with a 14" diamond blade) - are the carts that much better? I usually take the Jetta to work., but could take my wife's CRV on Fri/Mon.
            Pete C.
            http://blog.pjbj.ca

            Comment

            • Thread Continues Below...

            • #7

              Re: cutting concrete - garage floor.

              Re: cutting concrete - garage floor.

              This is what I would rent http://www.stihl.ca/ViewProduct.aspx...9jmX4gbVxdXkQ# with a wet cut blade and water attachment. If you can rent one like this http://www.stihlusa.com/construction/acc_TS700cart.html all the better. The job is too small to make a walk behind worthwhile. To be honest I wouldn't have any problem doing this with a worm drive skil saw and a garden sprayer. I use a blade roller http://thebladeroller.com/ so I can handle the saw with one hand and the sprayer wand with the other. Works like a charm.

              Comment


              • #8

                Re: cutting concrete - garage floor.

                Re: cutting concrete - garage floor.

                Originally posted by dave_k View Post
                If it was an employee I'd order the concrete for an hour after he started cutting, if it was me 2 hours minimum to cover time spent telling everyone how bad my back aches and how fast I could have done it in my prime.
                You may not be fair, but at least you're honest! LOL
                The more I learn, the better I understand how little I know.

                Comment


                • #9

                  Re: cutting concrete - garage floor.

                  Re: cutting concrete - garage floor.

                  If you are installing a car lift double check on the support requirements.

                  It's not hard to auger a hole for a pile if needed.
                  Egon
                  from
                  The South Shore, Nova Scotia

                  Comment


                  • #10

                    Re: cutting concrete - garage floor.

                    Re: cutting concrete - garage floor.

                    Originally posted by kevinhanna View Post
                    You may not be fair, but at least you're honest! LOL
                    Can I quote you on my web site?;-)

                    Comment


                    • #11

                      Re: cutting concrete - garage floor.

                      Real Technical Spec

                      Originally posted by petee_c View Post
                      Jim,

                      The spec for the anchors (it's tension with a 2 post lift) is minimum 4" of 3000psi concrete for the floor. If it's not thick enough, or the concrete is not strong enough, then the recommendation is a 4x4' footing 10-12" deep. With the car up on the lift, the posts will want to tip in. the anchors need to be strong enough to not pull out of the floor.

                      Bill,

                      I was just going to rent the concrete saw (basically a large chainsaw with a 14" diamond blade) - are the carts that much better? I usually take the Jetta to work., but could take my wife's CRV on Fri/Mon.
                      That is just some verbage in the directions. There must be an actual technical spec for the anchors and the installation of the anchors. Just installing deeper footings requires them to be tied into the slab with some technical notes such as drilling of rebar into the exsisting slap and roughing up the edge applying a coating to ensure the new footing bond to the exsisting floor and so on. There are several kinds of anchors on the market and compounds to ensure they dont' come out. Simply cutting a hole in the floor seems way to simplistic to belive that those footings will hold the weight on face value.

                      Comment

                      • Thread Continues Below...

                      • #12

                        Re: cutting concrete - garage floor.

                        Re: Real Technical Spec

                        I don't know anything about this specific lift but I've installed a fair amount of equipment. If the equipment is meant to be installed by the consumer the manufacturer will sometimes provide the engineering in their instructions that accounts for worst case scenarios. Sometimes they will make it clear that engineering IS required.

                        I would read the manufacturers literature carefully and call their support dept and ask if engineering is requires and ask for 'shop drawings" When you get the shop drawings or other manufacturers instructions look for any disclaimers and put them in a safe place just in case you need to take legal action. Don't do anything on verbal instructions.

                        First off I AN NOT AN ENGINEER this is just an opinion. The footing you are building is likely going to support the load going directly into the ground. keep in mind the the quality of the concrete and the bearing capacity of the soil are what will ultimately determine this.

                        What would concern me is the rotational force of the load from the car on the hoist which would want to lever the footing out of the ground or pull the anchor out of the footing. The manufacturer will know this better than anybody. When we install signs, hoists and similar structures that have a rotational component we counteract the force by going deep into the ground and having lots of mass in the foundation. The rotational force is then driving against the earth. If you are casting a new footing you may want to consider casting anchor bolts with a hook on them into the footing rather than drilled or chemical anchors.

                        Good luck with your project. You have all the time in the world so get it right and have fun with it

                        Comment


                        • #13

                          Re: cutting concrete - garage floor.

                          Re: Real Technical Spec

                          I took a look at the Max Jax website as I am looking for a lift and seem to move houses somewhat frequently. Pretty slick system.

                          I would be interested to know how it all works out for you when all is said and done.

                          Is it expensive?

                          Best of luck with the install.

                          Steven

                          Comment


                          • #14

                            Re: cutting concrete - garage floor.

                            Re: cutting concrete - garage floor.

                            specs on the lift, and anchors - almost 400% safety factor built in for a 6000lb vehicle. My vehicles are currently 2800,3000,3400 lbs.

                            http://www.maxjaxusa.com/specifications.html

                            @ Steve in Barrie

                            $1999 plus HST delivered to my home garage from Costco.ca

                            Princess Auto also has it for $2699.... but I think they will be changing the price.
                            Pete C.
                            http://blog.pjbj.ca

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