7.3N blocks, how hard are they?

Discussion in 'Builders' Talk' started by Hans_25, May 15, 2019.

  1. Hans_25

    Hans_25 Active Member

    Looks like I'll need to demolish and rebuild the spine wall (with very good supports in place) in 7.3N blocks, reason being is that there is an adjacent non-load bearing wall I want to remove and it is providing buttressing support to this spine wall, which is taking a LOT of weight.

    I will then want to put some sockets on this wall with 7.3N blocks, so need to chisel out for the back boxes.

    How hard are these blocks - am I going to struggle to chisel them out for the back boxes?
  2. KIAB

    KIAB Well-Known Member

    Easy to cut out for back boxes, can do old way with cold chisel & lump, or use sds drill with scutch chisel.
  3. dobbie

    dobbie Well-Known Member

    Cut out the shape of the box and then run some scores to depth with a 4 1/2" angle grinder,then cut out with a club hammer and comb chisel.
  4. Greentram

    Greentram Member

  5. Jimbo

    Jimbo Well-Known Member

    or dot and dab then you don't need to cut them
  6. Hans_25

    Hans_25 Active Member

    I'm not dotting and dabbing, horrid, and it won't line up with everything else.

    Good ideas above, thanks, seems like it shouldn't be too hard. I do have the square hole cutter stuff which I previously used on very hard red bricks - it struggled but did the job. Will probably give that a go but also have an SDS scutch chisel. Also have a small angle grinder, so have options.

    I used that plastic pattress jog years ago on my first house, was drilling the walls on Xmas eve :eek:
  7. dobbie

    dobbie Well-Known Member

    Do the job properly and get it rendered or plastered using hardwall,Dot and dab is is a throw it up quick get out the door method and as someone said in another thread "the work of the devil" it is your house,plaster or render it.

    The square hole cutters only really work on celcon/thermalite blocks in my experience.
    Hans_25 likes this.

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