How can I find if an impact energy of 2.7 J is enough for chiseling concrete slab ? I am thinking about purchasing a Bosch GBH 240, which has an impact energy of 2.7J. Please let me know if this rotary hammer has enough impact energy for chiseling an 10 cm concrete slab ?

I need this rotary hammer for jobs around the house, for example chiseling an 10cm concrete slab which has an area of about 0.25 sq meters, for drilling holes into concrete walls (6 to 12 mm diameter holes) and other things like that. I am in an renovation process in my house.

  • If that 10cm slab is 5 sq meters, then it is not the drill you should worry about, it is your wrists...
    – Solar Mike
    Nov 12, 2019 at 14:52
  • It is about 10 cm slab and 0.25 sq meters ... I did not specify.
    – beard999
    Nov 12, 2019 at 14:53
  • Why not rent a larger breaker with a 4 or 6" blade... Be much quicker.
    – Solar Mike
    Nov 12, 2019 at 14:56
  • I know that I can rent a breaker, but I need it for this job (the break) and also for repairs around the house, for example drilling holes in concrete walls (6 to 12 mm diameter holes) and things like that. Please have a look at the edit above.
    – beard999
    Nov 12, 2019 at 14:58
  • 2
    Use the proper tool for the job... That drill is fine for a small channel in a wall, but if you have 50m of channel there are better options. If you need it for holes in the future then buy it, but still I would rent the breaker.
    – Solar Mike
    Nov 12, 2019 at 15:01

2 Answers 2


That is not a huge area to break up. I would say if it is not reenforced you should be able to drill a series of holes and break it up,

I might get a masonry blade for a skill saw and cut channels then a sharp smack with a hammer it will crack into blocks.

I have wedged the edge of 6” slab off the ground then used a lead cannon ball (down rigger lead ball 35 lbs) over my head and slammed onto the slab to break it up with no drilled holes or saw cuts. Concrete is very brittle if not supported.

A few drill holes will help to guide the breaks and then you have manageable sized blocks to work with And possibly reuse. I have 3 or 4 hammer drills and to tell the truth they all work about the same except the hilti that is really not a drill / hammer drill but a hammer drill only. So if you purchase the Bosch you have a tool with multiple uses around the house, makes sense to me.


That sort of drill is great for drilling holes of that size in concrete, but it is a little light for breaking even a small concrete slab. You could drill a series of holes in a line and then break the slab apart with the chisel, but it won't smash it up like a big breaker.

A rule-of-thumb I read somewhere is that a solid whack with a lump hammer is about 1J

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.